Cleaning slate isn’t too difficult. It’s vital, however,to know what kind of dirt or contaminant you are trying to remove before you can make a decision as to which cleaning product is best suitable.
Slate comes in many different colours and finishes. Some of these are smooth whereas others have a textured surface. Undoubtedly, slate is a very popular material for flooring right now.
Slate generally has good resistance to mild acids so this gives you a much wider choice of cleaning materials than you would have with more acid-sensitive stones like limestone or marble.
So, how do we go about cleaning our slate floor?
First, you need to check whether the contaminant is mineral based? e.g. grout staining, cement, rust or general dirt. If it is, you would be advised to use a mild acid cleaner such as one based on phosphoric acid, for example, Grout Haze Plus . Beware though as any acid cleaner may etch the grout also.
In most other situations where you have, for example, general dirt and grime, wax, oil or a general build-up of old polishes etc. I would recommend using a strong alkaline cleaner such as Xtreme Clean for periodic intensive cleaning. For everyday cleaning, I’d recommend using a mild, neutral cleaner.
Here’s an Expert’s 6 – Step Guide to Cleaning Slate:
1. Ensure your slate is protected with a high-quality sealer: either an impregnating sealer such as Seal Gold+ which will give you a natural look with a mat finish and below surface stain protection. Or, if you prefer the look of wet slate, in so far as the darker colours, but still want a natural, mat, no-sheen finish, then look a good quality enhancing sealer such as Enhance ‘N’ Seal. Alternatively, you can use a coating sealer for a pleasant low sheen gloss which really helps any ongoing cleaning.
2. You must eliminate all grit – this is the major cause of all wear to slate floors. Ideally, place a dust mat both inside and outside the room which will help remove grit from shoes and prevent it from spreading to the slate floor.
3. Sweep and vacuum the slate floor regularly. This will also help remove grit from the surface of the floor.
4. Mop up and soak up isolated spillages as they happen. You shouldn’t leave strong contaminants such as coffee or wine to dwell on a slate floor.
5. Wash the slate regularly intervals using a mild, neutral cleaner. This will clean the slate but it won’t damage the stone, grout or the sealer used.
6. Less frequently, carry out a deep clean. For this, we recommend using a high alkaline cleaner. More in Part 2.
Update 22/01/13 – Check out this case study on cleaning slate
Copyright Ian Taylor and The Tile and Stone Blog.co.uk, 2013. See copyright notice above.
Hi,
I am assuming that the white marks are grout residue. If so then you may need to use the grout residue remover several times – as it will be a mild acid (and don’t be tempted to use a strong acid/brick acid or any other hydrochloric acid based cleaner). Such mild acid cleaners are designed to do the cleaning with minimal damage to the grout in the joints (which is exactly the same material as that which you are trying to break down on the slate) – so it is often necessary to repeat the clean several times, each time taking a bit more away. Also you may need to use a scrubbing brush.
Hope this helps
Ian
Hi Thomas,
Well first of all WD40 is a great product – but not for sealing slate! – I can see the thinking, an oil thinned with solvents, a bit like a sealer, except the oil is designed to be a lubricant (yes also a water repellent) but it does not form a polymer film – an inner skin to keep stains out. Also, I do not imagine it lasting too long either – it will remain mobile (not ‘set’ or cured like a sealer) so it will be removed with normal cleaning over time, it will even gradually just degrade on its own – so all in all – not an effective sealer (bit of a trade ‘cheat’ in my opinion).
OK, the white marks could be due to some impurity in the water, if your chimney is limestone, for example, water could have picked up some soluble lime (and depostited it on the slate as the water evaporates) or if you live in a hard water area you could have a high calcium content (don’t think Glasgow does mind you) again you get calcium deposits left behind. Or it could be residue from detergent.
It could also be that the WD40 oil slightly darkened your slate and the sitting water has washed more out of it in those areas. Do the white areas disapear (albeit temporarily) when the slate is wet? – if so try a little acidic liquid – like a clear vinegar – just to see if there is anything mineral (the acid will disolve it), rinse and dry and look at it again. if it has lessened the problem, get a mild acid based cleaner and try that.
Conversley the white marks could be caused by acid etching – acid rain being the culprit or (and I am no chemist) I beleive it may be possible that some forms of soot, (depending on several things) can have a low ph (acidic) although often they are alkaline – so rain water picking up soot, can become acidic which could on some slates cause a slight etching. The reverse could be true also, if the water + soot resulted in an alkaine solution – that would have the effect of stripping out the WD40 – or what remained of it.
If acid etching then masking the etch marks may be an option, if all else fails, try adding a bit more WD 40 – as it was used before, it may top up the oil and make the look more uniform – not ideal, (this is where I would normally recommend an enhancing sealer but it is too risky now, the sealer mey not penetrate correctly due to he presence of the remains of the WD40) but it may mask the marks.
Hope this helps
Ian
Hi Ian – many thanks for your reply…it’s very helpful. I’ll try a mild detergent and hope that works. I’ve noticed that the residue seems to be gradually improving now (after about 10 days!)…so am hoping that, with a bit of detergent, the problem might go away.
Thanks again,
Nick
Hi, in trying to be helpful my teenager washed the kitchen slate floor with a product callede Cillit Bang leaving bloches and stains all over a wide area, is there anything I can do to renew the appearance thank you
Hi Charlie,
I have heard so many storeis about this product, itis not that it is a bad product, just that it contains acid and should not be used on acid sensitive surfaces (like many stone and grouts).
So, what could have happened? Well, if the slate is a coloured vairiety, with the colours coming from minerals such as iron etc, then an acid can dull and etch them, taking with it some of the colour intensit which could leave the slate looking drab. If you have white patches then there is another possibility, that there was a feint, barely noticeable grout haze or other film on the surface and the acid has etched this rather than the slate. Or, perhaps the slate is fine and the acid has brought disolved grout grout out of the joints and left it on the stone.
Try using a good deep cleaner (alkaline) and a scrubbing pad to see if you can loosen anything from the surface. If the actual slat eis damaged itslef, then what happens when it is wet? – does the colour come back, at least until it dries out?. It may be possible to use an enhancing sealer on this – provided the slate is not already sealed.
One other thought that ocurs to me, and forgive me, but not eveyone will correctly identify the stone, are you 100% certain the stone is a slate? – it is just that not all slate is sensitive to acids where other stones, like likemsstone for example typically are very sensitive.
If you could sned some pictures I might be able to help more
Hope this helps
Ian
ih ian iv just bort some second hand slates to do my garage roof but when iv looked at them thev got bitumem tar like substance thaks if you can help me to find out how to clean them
Picked up our Italian honed slate hearth today.
Would appreciate any advise regarding cleaning, and sealing the stone.
Didnt get any advise from the store due to collecting from pickup point at the rear of the building.
Hi Peter,
To be honest the only way to chemically remove tar is a strong solvent. First scrape as much of the solid tar off as you can then use a solvent, you could try white spirit or turps etc. to get the residues. It may take several attempts.
Hope this helps
Ian
Hi Taffy/Ceri?
I do not know precisely what slate you have but if it is honed then it is smooth so an imprgnating sealer is the way to go. You may or may not want to consider an enhancing sealer – if the slate is at the moment unsealed – (and you may want to check that the factory/supplier has not put anything on it) does it darken a lot when wet? – if so do you prefer it in this darkened state, or natural? If you prefer the darkened state you could use a good enhancing sealer like Enrich n Seal or Enhance n Seal – make sure you want this though as it is not reversible.
If you want the natrual look – just a good quality impregating sealer, if the slate is really dense, you may find a solvent based one easier than a water based, if it is qyite porous (slate varies a lot) then the reverse might be true.
For cleaning, a neutral ph cleaner for routine cleaning, something a little higher in alkalie for heavy, periodic cleaning. If it is just the manufacturing dust/sludge, then some washing up liquid and water might be all you need.
Hope this helps
Ian
Hi Ian,
i have two slate showers the floors are white with limescale. what do i use to remove limescale. the grey slate looks as though it is starting to flake,the cleaner i used was too acidic.
thanks
Ana
Hi Ana,
OK, to be honest, if it is a lime-scale issue, and you have a slate that is not sensitive to acids (nor anything within splash-contact proximity) then an acid was the right thing to use – as long as it was a safe one (i.e. not brick cleaner, hydrochloric etc.).
The acidic cleaner should not be making the slate ‘flake’ – Flaky slates are flaky on their own, and sooner or later they will start to loose any lose flake’s but usually this settles down quite quickly, unless they are really bad. (I have a geologist friend who would argue that some stone, sold as slate is not technically slate at all, but a shale or some other sedimentary rock that has not quite made the full metamorphic change into slate, so it is a much younger rock – the less dense, often more colourful, dusty and flaky slates that we see may fall into this category – nothing wrong with them per se, but they can be more susceptible to flaking).
I would remove any loose flakes, check the rest of the slate is sound then clean the limescale. Use a safe acid (look on the back if they are tile grout haze removers and they contain a percentage of phospohric acid or one of its replacements, it should be fine).
Pre wet the floor, apply the acidic solution (may not have to be neat – remember the stronger the solution, the faster it will work BUT, the more potential damage it can do to the grout joint, so start with say a 5:1 dilution rate). Let it sit for a couple of minutes then scrub with a pad or brush.
Rinse well with clean water, (still scrub a little) to remove the acidic cleaner and any dissolved lime-scale. Dry the slate with a towel/paper towels.
Bear in mind that the lime scale has come from your water, so drying the slate (i.e. removing the water) before it has a chance to dry and leave a deposit of more lime, is a great way to help prevent future build up. Let it air dry and have a look. If necessary repeat. The other thing to watch for is the acidic cleaner etching your grout, if your grout is pigmented, or dark, it may now be significantly lighter in shade (maybe already as you have already used an acid). Acids can bring tiny amounts of dissolved cement out of the grout, the calcium from the grout, reacts with the acid to create calcium phosphate which is a salt – and can look itself like a white, lime-scale deposit – so it in theory it is possible for the actual treatment to remove the lime-scale and replace it (at least partially) with another similar problem (again it is broken down by more acid cleaner) – so clearly rinsing and drying help prevent this.
Once you have got the lime-scale removed, and any flaky bits sorted out, let it dry and you will probably need to re seal (especially if some flakes have come of).
From this point on, make a point of drying the floor, not on every occasion perhaps, but frequently. And then use a milder perhaps citrus based cleaner periodically to keep the lime-scale at bay- again, rinse and dry each time you do this. Also a cream abrasive like Microscrub is a non-acidic alternative for keeping it under control (once the initial build up is addressed) Hope this helps
Ian
Hello Ian, thanks for the advice, i will try this and seal the tiles. then do regular maintenance.
Ana
Hi Ian.
I have had 120msq of slate laid throughout my house. Days after it was laid builders marked large areas with plaster and paint which I am finding it difficult to remove. The floor is disappointingly stained and builders have scrubbed certain areas which has made the floor lighter and dull. It is a natural riven slate and also seems to have grout trapped in the groves on some tiles. Obviously it cost a lot of money to buy and lay and I want to know how I can get the colour of the slate looking consistent throughout the house.
Many thanks,
Lauren.
Hi Lauren,
The dull areas that the buliders have scrubbed are dull, hopefully because they have only partially cleaned, and have not rinsed well. This means they may have left residues that have now dried on the surface again.
In most cases like this, with a good quality slate it is usual to use some form of proprietory acid-based cleaner. Provided your slate is not acid sensitive, and you have not got a highly pigmented grout, this may be the best thing to try. Try to find a product that is based on phosphoric acid or similar, DO NOT use a brick acid or one based on hydrochloric/muriatic acid as this can do more harm than good.
The phos acid based cleaners are mild and weak, they are already diluted and can be diluted further, they are designed to take small films off the surface whilst doing minimal damage to the surface of the grout itself.
Test the cleaner neat on your slate in an inconspicuous place just to make sure it does not damage the slate. Then do the following:
1. Pre wet the floor with a mop or sponge
2. Mix your cleaner as per instructions – typical dilution maybe 1:5 0r 1:3, apply it to the floor
3. Leave it to dwell for about 3 minutes
4.Scrub with a scrubbing brush or wite pad, you may nees a plastic scraper to get into some of the deeper parts of the texture
5. Pick up the solution with a mop or wet vac
6. Important step: rinse the floor with fresh clean water, mop up
dry the floor with moving air and/or towels
inspect and repeat if neccesary – it may take several goes as you are taking very thin films each time. The trapped grout in the riven texture may need some local neat application of the above.
Hope this helps
Ian
Hi there Mr. Slate genius!
Excellent advice I see here and so well put so I’m really hoping you’ll be able to help me
I have my front garden tiled in riven dark grey slate tiles (30cm x 30cm)
Having saved for an age to get new double glazed sash windows put back in the house we also decided to get the front completely cleaned
ie. All the brickwork cleaned and re-pointed.
They tried their best to keep the run-off off the tiles but needless to say the acid used to clean the bricks has bleached the tiles in a lot of places :0(
It’s etched some areas but some, where gaffer tape, was stuck down is fine so the tiles have a 6cm wide line through them in places!
So, basically I have white spotted and patchy tiles on about a quarter of all the tiles.
I had previously sealed with HG Impregnating Sealer but acid being acid it made no difference
Before I start to weep and sand my little fingers to the boney bone could you possibly offer some advice?
Many thanks,
Darlene
Hi Darlene,
You may be ok here. First of all, dark riven grey tiles, that you had to save for suggests good quality slate (Welsh, Cornish, Brazilian etc) which to my knowledge is not generally all that acid sensitive. You could have a more shale-like Indian/Chinese type product I suppose and some of them can be more susceptible to etching due to their make up.
However I think a more likely scenario is this: When an acid attacks cement in grout/mortar it kills some of the colour (giving the bleached etched effect) I think you have a residue of the run off that has been left to dry on the surface. Builders and conctractors seem to delight in using acids, that are often to strong (hydrochloric), frequently not diluted to the recommended rates, blasting the problem with their massive acid overkill, then failing to rinse the away the aftermath. I suspect that if you take some more acid (and I mean suitable one, not a brick cleaner so a cement residue remover based on phosphoric acid) dilute it, pre wet the floor, then apply your solution, scrub with a bristle scrubbing brush for a few minsutes then rinse away with clean water – this is a garden so use a hose pipe and clear that acid wash away.
Let it dry and repeat – do this several times, each time taking a tiny thin layer off the tiles, then rinse away again (the risning is the key part – imagine washing your hair with way too much industrial-strength salon shampoo, and not rinsing! – this is what contractors tend to do with acids). You may have to get down on your hands and knees to pay more detailed attention tothe noks and crannies but I am sure you will get there.
I do not think the acid has done anything to the sealer, the HG impregnator, [or any brand] could not have prevented this as it is on top of the sealer. There is a slight chance that the impregnator has not penetrated the very dense slate, just sat on the top, therefore not properly bonded and in this case the acid wash could take some of it off and possibly turn some of it dull/white in which case stripping the sealer may cure the problem. However I think the first situation is morem likely.
Hope this hleps
Ian
many thanks for the good advice, i have applied vinegar as a means of bringing the slate to a uniform dull slate grey finish with no signs now of unsightly staining. i do not think there is any trace of the wd 40 left. what steps should i now take to seal the slate i have some filastone plus purchased for some granite sealing just recently would that seal the slate or what would you recommend?
Hi Tom,
Well I am not sure I recommend using vinengar! but, if it has worked, I can only asume the WD40 was not deepley embeded in the slate (and that perhaps even soapy water might have removed it).
However, all seems well so just make suire there are no traces of the vinegar left and that it is perectly dry before sealing. I have never used the product you mention but it appears to be an impregnatiung sealer that also enhances. I cannot think why it would not be suitable, but I would just double check witht the supplier.
Hope that helps
Ian
Hi Ian
I have black slate floor tiles in my bathroom, presumably sealed by previous owner as there is a bottle of sealant left under the sink!
Over time, water from the shower spilling onto the floor has left white marks on the tiles, and I have tried using general detergent and soap powder and using a toothbrush on the tiles, and nothing seems to be removing the white stains.
What can I use to remove the white stains, and how can I make the black slate tiles look ‘clean’ with a sheen?
Many grateful thanks for your advice!
Best wishes
Chris
I have found your site and hope you can help me!
I have had a grey riven (chinese!) slate laid in my entrance hall and utility room – the tiles were very mixed colours as you would expect. They were sealed properly by the tiler.
We used the cleaner given to us by the tiler and after the first wash a white blotchy, bloom appeared on some of the tiles – it was very noticeable and I asked the tiler to come and look at it.
They stripped some of the tiles as they thought that they were not sealed properly – I am not sure of the product they used but the smell was overpowering in the house (running eyes etc) and they used a scrubbing brush to remove the sealant.
Now the tiles that they treated are very bleached out – one to the point of being silver, and others with white circles on. They are considerably paler than the tiles they left. Some tiles also have a rusty circular marks on. None of the tiles are a uniform colour anymore.
Help! The tiler is saying that the tiles looked like that when he laid them – not true! Will they come back when he reseals them or has damage been done when they removed the sealer?
I would really appreciate your help as I feel we are being fobbed off and I am going to end up with a floor that looks like a mess!
Thanks Ian.
Hi Chris,
OK first of all the white marks, most likely to be soapscum or calcium type depostits left behind by the water, or a combination of both. Over time it builds up. Also, on a black slate, white marks show quite easily, so even the smallest traces of minerals can quickly appear to be quite noticeable. My guess is that had you got a limestone floor you may not even see them. Black slate is usually quite dense, given that it has been sealed also I am pretty confident that the white marks are just likely to be on the top and shoule be removable.
You could try a mild abrasive like Microscrub (you can get it on the All For Stone link top right of the site) failing that, the usual route is a very mild acidic cleaner again see AFS – DO NOT USE A BRICK OR HCL BASED ACID. Dilute the cleaner really well (it won’t take much) apply, leave a couple of minutes, then a quick scrub with a white nylon pad, then rinse with clean water. Lastly, dry the area wqith a towel. I would also recomend tis as an ongoing idea, drying the floor before the water splashes can dry and leave behind any deposits.
As for getting it back to a shine, that depends ion a couple things, what the previous owners sealed th efloor with, and what type of surface the slate has. If the slate is very smooth, or if the slate is well sealed with a good impregnator it will be hard to get a coating sealer to lie flat and bond. IF the slate is textured or riven, and if the slate was previously sealed with a coating sealer then you may be able to apply a new one, for example Seal & FInish Low Sheen or similar.
Hope this helps
Ian
Hi,
It sounds to me as though the cleaner you were left with was either not suitable for the sealer; partially stripping it on the first wash, or the sealer is not water-safe. After that you say they used a really smelly product to strip the sealer, this sounds like a solvent stripper and from what you describe as being left , I suspect that you have not got damaged tiles, rather damaged sealer: If they applied a coating sealer, and it was quite thick (and shiny) then a stripper may take two or more goes to remove it, the first attempts merely taking a ‘layer’ off the top and leaving some now damaged sealer still to be removed, it is as thought the selaer has been delaminated, a bit like when aged sticky tape is left on a wall then pulled off some weeks/months later, only part of it comes away, leaving a white/dull ‘back’ part behind.
If this is the case, another attempt with the stripper should completely remove it and then, after the floor has been rinsed and dried, it should be back to the pre-sealed state.
Hope this helps
Ian
Hi Ian,
So, SO sorry for not thanking you sooner but I thought I’d wait until I’d tried your suggestion
I’ve now tried the cement residue remover but still no joy
I now have a horrible feeling that I have 40 tiles to fine sand by hand!!
It seems to be the only way to remove the white ‘bloom’ and as an electrical sander smooths the lovely roughish surface then I can’t use that either.
So, it’s grab a cushion and every weekend I’ll be sitting out there doing a tile at a time :0|
Really appreciate your help though, it was worth a try
Kind regards
Darlene
OK,
you could try an undlited strengh of the same acid, allow it to dwell a bit longer and use a soft wire brush. If when using it neat, you do not see any fizzing, then the acid is not reacing with the cement, (which means it is not doing anything) so you may need to try a solvent (to break down some polymers first)
Feel frre to email me via the site.
Ian
Ian,
We had a ‘professional’ out yesterday to clean our 15 yr old natural slate tile floor. The tiles had what appeared to be condensation residue from mineral deposits where our humidifier sits in the winter. The floor had not been re-sealed since installation.
The guy used diluted muriatic acid and scrubbed the floor with a wire brush. Now, the entire floor is discolored and there are what appear to be salts in the grout.
He is to return today to apply a ‘shiny’ (his word) sealer. Needless to say we are less than satisfied. We couldn’t believe how badly the floor looked. Other than applying this mystery sealer that ‘might’ work to get rid of the discolorations and restore the color, his suggestions ranged from renting a machine to installing a new floor.
I can send a picture. I don’t know what the original sealer was. We would greatly appreciate your opinion. We should have gone with a company instead of an individual recommended by the tile store.
Regards,
Karen
Hi Karen,
Sorry to hear this, I take it from your use of the word muriatic, you are in the USA, in Europe we refer to the acid as hydrchloric – either way, it is nasty stuff and WAY over the top for removal of a little bit of mineral deposits. better to use a phosphoric acid-based cleaner or similar that may need to be used more than one rather than the ‘sledge-hammer to crack a walnut’ approach of muriatic.
Depening on the type of slate you have, and its mineral composition, you may have suffered some permanant damage/etching – hard to say from email alone. (If you have really bad etching you may have to call on a stone floor professional to see about having the floor re-ground/re-finished)
Regarding the salts in the grout – probably true; I’ll preface this by stating that I am NOT a chemist but basically if you react an acid with an alkalie, (base) you tend to get a salt, plus carbon dioxide and water as the result.
In the case of Muriatic on grout – we are essentially dealing with hydrochloric acid and cement, or mainly calcium carbonate (alkaline) – by exposing the calcium carbonate to the muriatic we get water, CO2 and a salt called calcium-chloride. The salt is harmless enough but, we have replaced some of the cement in the grout (which holds it together) with a salt, (which does nothing). So we have degraded the structure and integrity of the grout, possibly leading to premature cracking and erosion. the salts will wash out with a mild, and far less destructive diluted phosphoric wash but they will leave holes. Also the etching process has roughened up the surface, which has the optical effect of lightening the colour of the grout (rough surface scatters light like the saw-cut face of a stone Vs a polished one).
The etching may tone down over time with use and washing etc but it may take a while.
I would ask if, when wet, the floor (slate and grout) looks better or even acceptable, if it does then the proposed coating sealer MAY help, at least a little – only a test in an inconspicuos area will tell, but my advice is to not let him off the hook in terms of responsibility until you have thoroughly tested this. If wetting does improve the look then you may be better with a good enhancing selaer, in the USA, you could use Enrich n Seal by Aqua Mix ( I would call their tech services and explain) it is an excellent product for this and will darken the slate and the grout. however it is NOT SHINY, if you want a gloss you will have to go the coating sealer route, you cannot add a gloss to the Enrich n Seal route – (it is such a good sealer that no coating will sit on it correctly)
Hope that was some help
Ian
Ian,
Thanks so much for your well informed and immediate response! Yes, we are in the US. Yes, the floor looks better/probably acceptable when wet with water. We are not looking for a shiny finish. I don’t know the type of slate but it does have a rough (natural) finish.
We are allowing him to come out and test a small area behind where the fridge sits this morning.
As a note, after reading your posts I ran into the kitchen only to discover the finish on my relatively new KitchenAid stainless steel mixing bowl and the stainless steel tray on our kitchen scale is permanently damaged from the fumes.
I would definitely consider the etching on the tile ‘really bad’. It appears in the ‘grain’ of every tile. The grout isn’t so bad, only a few places that are white which were previously dark gray.
Thank you again for your time and for sharing your knowledge.
Karen
Ian,
I thought it worth posting that we may have solved the problem. Our guy brought a bottle of TileLab Heavy-Duty Cleaner Stripper. Before applying it we called the company and based on our info they recommended applying it full strength to a test area and waiting 15 minutes before using a scrubber then sponging it up with a clean, wet sponge. So far, it looks like it is working beautifully.
The problem: WAX! And by figuring this out and by not charging us for yesterday’s work and product, he redeemed himself.
Apparently, years ago the floor was heavily waxed. The product is working much like a wood finish stripper. We can see the wax sort of bubbling up off the surface.
Also, our guy brought with him a bottle of Aqua Mix Enhancer (seeing that also restored our confidence) as well as Stonetech Impregnator Pro Sealer.
After reading your response to the pinned forum post, ‘Slate- Sealer Disaster, advice needed urgently’ and I have a question. Given this is a high traffic kitchen floor, the main entry into the house and mud/snow/ everything room, would you recommend the coating over the impregnator?
Thank you,
Karen
Hi Karen,
Thanks for coming back with this – it great to have a happy ending!
Wax! – OK, well it is hard to second guess what has gone on in the past sometimes. Well the Tile lab should do a good job of removing it, might need two goes plus make sure he rinses it WELL and then dries it.
As for the enhacning sealer – if it is your intention to use thisn then DO NOT try to put a coating sealer on top – if using the enhancer it is a case of using it on it’s own, and furthermore the floor must be bone dry before you do it. Even with the other impregnator, you will find that a coating sealer may not want to bond on top – so it is either or, depending on whether you want a gloss finish ir not, bear in mind also, that a coating sealer will require more frequent maintenance and reapplication.
As for redeeming himself, what about your stainless-steelwork?
Glad it worked out
Ian
Thanks, Ian. I’ll go with the impregnator. He is definitely getting his money’s worth out of his knee pads and he’s gone through at least 40 gallons of water!
He offered to polish the stainless “or whatever I can do to make it right”. He is busting it so hard right now that I hesitate to bring it up again until he’s done.
Happy to refer any and all who have an interest in stone/tile to your site.
Take care,
Karen
Hi Karen,
Great news, sounds like he is a hard working, reliable guy, just made an honest mistake (happens to all of us), cudos to him for seeing it through, and to you for giving him the chance.
take care
Ian
Hi
Wondering if you could help. We have had a stove fitted with a smooth slate hearth. A bottle of red wine has been dropped on the hearth and where it has spilt the slate has gone a paler colour to the rest of the hearth. It was cleaned straight away with washing up liquid and water. After reading the rest of your blogs I think it may have been etched??
Many thanks
Tracey
Hi Tracy,
Many slates are not known for their susceptibility to acid etching, but some of course can etch. So yes it is possible that the acid in th wine has etched the colour and made it a little lighter. If the surfacce feels a little more dull or powdery than the parts that remain ok, then that is another sign of etching. Also, some slates have components that are not 100% ‘fixed’ in the stone, so colour pigment could be mobile – meaning that with a concentrated cleaner, or an acidic liquid like the wine, could strip out some of the colour.
It is hard to say without seeing it, but it may get better over time. You may be able to use fine sand paper/emery paper with a little water (wet & dry paper and gently blend the etches back into somthing close to the rest of the slate.
It may be possible that an enhancng sealer could darken the patches down again and make everything look more even, provided the slate has never been sealed with anything previously. If the slate looks ‘nice when wet’ then this may be something to consider.
Hope this helps
Ian
Hi
Great site but my mind is doing overtime on what to do.
I have grey slate flooring in the kitchen (Homebase), which was laid approx 6 years ago. It has never been sealed, and has been fine up until now. It now has a few water marks and in general is looking a bit dull. I was wondering which product would be best to use for a deep all over clean (floor area 10’x 18′).
Thanking you in advance for any advice.
Karen
Hi Karwen,
this sounds like a standard periodic deep clean is allthat is needed. Over time slate will get grubby, and I suspect that 90% of the lack-lustre look is dowmn to a build up of the tiniest traces of both dirt and detergent residue that has built up a ‘patina’ over the last 6 years.
Use a good high alkaline cleaner like heavy Duty Tile & Grout Cleaner (see All for Stone ad on right). Pre wet the floor, then mix your cleaner say 4:1 with warm water, apply it to the floor and leave it for 15 minutes, without allowing it to dry out. Scrub, EXTRACT (mop or wet vac) RINSE – with clean water, and extract that, lastly polish dry with an old towel.
At this pount if both the slate and the grout joints have come up clean, when dry, you may consider a sealer.
Hope this helps
Ian
Wow chuffed i stumbled across this page, you sound very knowledgeable.
Ok so here goes…..
We have just been given an old slate bed of a snooker table, we are going to use this as a fire hearth. I would like to try and bring it to a darker colour as it is light grey. Do you have any suggestions as what we can use to
: Clean it
: Buff/Polish
: Darken
:Seal it
Thank you very much for your time
Hi Emma, lucky you!
Having never removed the felt off a snooker table I do not know what may be on the slate, but expect it was glued down with somthing so there may be residues of a glue. Try a least aggressive to most aggressive approach.
First try the least aggressive/most gentle method and if that does not work, move up to somthing a bit more aggressive.
So, I would first just try a mild soapy detergent – like washing up liquid with plenty of water, and a WHITE scrub pad the type for scouring dishes (often white nylon pad on green sponge?) DON’T use the GREEN scourers as they are a bit more coarse.
if this does not clean it, then use a high alkaline detergent instead, if that does not work, then you may have to go to a stripper like Sealer and Adhesive Remover. (see All for Stone opposite).
When well rinsed and dry you can look to seal. Notice when cleaning it, if the wetting action made it go much darker, and darker in a desirable way. If so and this is the effect you want, then look to an enhancing sealer (such as Enrich n Seal), make sure the slate is 100% dry before you apply it, and do not leve it looking wet – even if you like the look of it, apply the enrich n seal to a dry stone, leave it to penetrate for 5 to 10 minutes then buff dry to leave a matt finish.
Give this a few days to fully cure, you will not be able to put a gloss coat on top but you could apply a buffing polish like ‘Brilliance’
hope this helps
Ian
Hi Ian,Glad to have found your helpful site. We have just purchased from the reclaimation yard a piece of slate for a hearth. It looks to have been a previous hearth and has some rust stains and gloss paint marks which we hope to remove! Do you have any ideas for cleaning please and sealing.
Many thanks
Sue.
Hi Ian,
We have an en-suite shower made from black slate tiles. It was proffessionally done, sealed, grouted etc.
We ended up renting our house out and the previous tenants didn’t seem so particular about cleaning. We now have what looks like limescale covering all the tiles (it’s a grey appearance). We have tried limescale cleaners but had no joy, is there anyway we can paint the tiles back to black and then re-seal them?
Thank you for your help.
Sharon
Hi Sue,,
OK, for rust typically go for a very mild phosphoric acid type cleaner, use dilute with water, may take several applications. Only other thing to say is that this is usually effective only for surface rust deposits (rust that has been left on the surface) should you have rust from within the stone due to minerals contained in the slate, then this may not be easy or even possible to remove.
For paint, use a spaint stripper or solvent if it is thick and stubborn.
Having said that often paint is relatively ‘new’ as a contaminant, so may be on top of a layer of general dirt and so may well come off with a normal deep clean (it comes away with the dirt that it is stuck to)
What do yo have most of? – paint, rust, genral dirt? – if it is just in need of a general deep clean, with a few spots of rust and paint, then go for an alkaline cleaner, you may well find the rust and paint come off duinrg the cleaning process, particularly if you boost the cleaner with Microscrub. If not then tackle them in isolation afterwards.
If you need them here is a list of suitable products, avaiable from All For Stone (click link: http://www.allforstone.co.uk)
1. Heavy Duty Tile & Grout Cleaner
2. Microscrub
3. Phosphoric acid Cleaner/substitute (or Exrtreme for really bad rust)
4. Seal & Coating Remover (powerful but safe solvent)
for sealing, I am guessing that the surface is smooth, or honed. In which case avoid a coating sealer, use an impregnator that leaves no surface coating. Choose either a no-colour natural sealer or an enhancing sealer if you wish to permanatly bring out the colour
Hope this helps
Ian
Hi Sharon,
Limescale (and soap-scum) can indeed leave a greyish depositi on the slate. The good news is that it is on the slate and therefore should come off, leaving the real slate behind. Unless, it is acid damage to the actual slate but I am guessing this is less likely.
The limecale removers you may have tried are probably acids, they work by reacting with and disolving the mineral deposit, but they have to be used correctly: leave on the slate for a short period, not long, usually a few minutes, do not allow them to dry out, scrub with a scrub pad, then the all important part, RINSE well with cleanwater. then I would dry them down with a towel.
ON NO ACCOUNT TRY TO USE ANYTHING STRONGER LIKE A BRICK ACID OR HCL
the acids used for this are often, Phosphoric, Citric or sulfamic. These are relatively weak in solutions that are available to the public and that may mean several applications. In deed thick layers of limescale may look worse after one slight cleane, or even a couple of inccorrectly executed ones, as the acid may have a) been left to dry (and thus not achieved much) b) reacted with the limecale and produced a halrmless slat as a by product, which is now also ontop of the slate or c) has removed say half or a third of the deposit, like taking only one layer of skin away with dermabrasion etc, so additional cleans, done properly with the right product may well help follow my procedure below for this:
1. pre wet the slate with plain water (stops acid from drying to quickly, keeps it at the surface)
2. mix correct solution of limecale remover (or use Phosphoric ACid Cleaner) as per ionstructions, apply to slate. walls may need you to keep reapplying it due to the efffects of gravity, use a spray bottle
3. leave for a few minuts, keep wet with more solution
4. scrubb hard for several minutes
5. RINSE WELL WITH FRESH WATER – easy in a shower.
6. Dry walls with towels – removes all water and any traces of calcium or other deposits tha may be in the water.
7. inspect when dry and repeat if required.
Hope this hlpes, as far as sealing goes, if they have been presealed, then I suggest topping up with the original sealer if possilbe
Cheers
Ian
Thanks Ian, we will give it a try.
Hi Ian,
I hope that you can help me. Last year we purchased a black Caithness slate hearth. It was left in our garden for a number of months while we renovated and unfortunately it has now turned predominately brown. Any ideas on how we can restore it back to the original colour?
Many thanks,
Morag
Hi Morag,
Just incase it is this simple, try a good scrub with a mild detergent, or with the tiniest bit of bleach in water (try a very small test spot) I am just thinking that if it has been out in the damp, it is is possible that it has just got coated with some brown mildew or algea type organism.
However, it could also be oxidisation (i.e. rust). From what I understand, Caithness stone is actually a kind of siltstone, rather than a slate, they are both very similar types of rock and contain simmilar clays/silts etc and the minerals that often go with them.
It is quite possible that some form of iron mineral is present. If there is a lot of iron present, then inside the stone, away from moisture and air, it will stay fine, but when a new surface is exposed (in other words when the slate is cut and polished or finished) some fresh iron may be exposed. As it has been outside in the rain and got wet for long periods, there has been ample time for the iron to react with the water and oygen in the air, so it begins to oxize, producing the ‘rust’ colour.
You may have some success with a very mild phosphoric based acid cleaner – suggest (pending results of first test above) that you try to get some Phosphoric acid cleaner from All for Stone or similar. Use dilute on pre-wetted stone, agitate andrinse, then dry off
Hope this helps
Ian
Ian, We recently had a black slate floor installed. It was sealed at the time of installation. The coloration was inspected and found to be fairly uniform. A couple of months later, while the house was still under construction, metallic gold deposits suddenly appeared on a number of the tiles. The deposits were random and appeared in more than one location on the floor. The deposits have a different (rougher) texture than the rest of the tile and it looks like something spilled, but the installer says it’s a natural part of the stone. Have you ever heard of natural metallic deposits suddenly appearing in sealed slate? Thanks for your thoughts.
Hi Ian,
can you recommend a slate cleaner brand? I can’t seem to find any floor cleaner that expicitly says is suitable for slate and have ran out of the cleaner we were given when the floor was laid.
We have slate flooring in our entrance hall, utility and kitchen as we were advised by our builder that it was extremely durable.
I’ve unfortunately found it quite difficult to keep clean (even though it was sealed twice) and it doesn’t seem to matter how much I clean, but the floor still looks dull with persistent marks. Do you have any advise on how to tackle this?
Many thanks,
Dawn
Hi Liz, those natural metalic deposits sound like rust – and yes it is very common.
Two possible reasons, one is somewhat more obvious to spot, and that is simply somthing above the slate that is rusty, like a metal bucket, maybe a haning basket made of metal that has water drippig from it, some other fixture or fitting that is rusting and is either in contact with the floor itself, or has water coming fro it that is.
The other and perhaps more common situation is that minerals within the slate itself are oxidising. Slate is made up of many original components like clay, and these can contain minerals, and sources of iron in one form or another. When the slate is first cut and finished into tiles, a new, fresh split face is exposed. Up to this point that part of the slate was ‘inside’ the stone, not exposed to oxygen and moisture
Now the slate face has been exposed to both, and any hitherto invisible iron-bearing mineral, has been allowed to react with water and air, the moisture can come from above – cleaning and washing, or from below (rising moisture, most slates are pretty impervious so moisture travelling up through them from below is less likely), or from installation, there is a lot of water in grout, and maybe moisture from the sealant?
So any number of reason but, often slates like this will simply react with the ambient moisture within the air over time, and so this I think is the most likely explanation – the iron-bearing minerals, now exposed, have over a small period of time begon to oxidise or rust -hence the colour and rough feeling.
Much of this will rub off, and you could reduce it with a little dilute phosphoric acid cleaner – but it may come back over time, however each time you clean it it may reduce in intensity and take longer t come back. You may or may not eradicate it completely. It is however a natural occurance with this type of stone, just like sap coming out of pine, or wood fading or yellowing over time.
Hope this helps
Ian
Hi Dawn,
One of the reasons that you won’t find a dedicated ‘slate seaerl’ is that most stones can be treated with similar cleaners and slate is usually pretty resillient stuff.
Look for a general mild, neutral cleaner that says it is ok for tiles and stone for regular cleaning.
Apart from that, use a mild to medium alkaline cleaner like Xtreme Clean by All For Stonefor deeper cleaning.
Try to avoid acid based cleaners.
The dullness you report may be a reulst of the original sealer wearing down -this is normal for coating sealers, or it could be a build up of detergent, leaving a patina, normally fixed by giving the floor a good deep clean with an alkaline cleaner then rinsing well with water and even rubbing it dry with towels.
If you had a coating sealer (one that was on top of the slate, that maybe had a sloght sheen to it) and this has worn (through alkaline cleaners and/or wear from foot traffic) then this would account for the dulling and the makrs (as the sealer has gone, so to has the stain protetction) – a good deep clean as detailed above then reseal should fix it. From then on try to use neutral or mild cleaners rethat than alkaline for every day use.
If it was an impregnating sealer then again it may have diminished a bit so again, deep clean and top up the sealer when done.
Hope this helps, if you have further questions please feel free to ask, if cou could tel more about the sealer used that may help
Ian
Aaargh! LEMON JUICE! Left by me on our friends beautiful slate kitchen top for an hour or so. I feel completely mortified. Now its very white – etched by the acid? I’ve been through previous answers and seen vinegar and wine – will this be the same or is this a qualitatively different problem?
Short of dismantling the major part of the kitchen to take the worktop to be refinished, what else can I try? Start with a dilute bleach or other alkali?
Many thnaks Ian, you are providing a major public service here – third from the top for my Google search! Does that mean you can earn some money selling advertising space here – for stone companies and cleaning products? You deserve it.
Steve (Brighton)
We have a slightly textured black hearth for an open fire. We did not seal it when it was installed and while using a fire log [which I guess contains parafin] some bits from the log fell onto the hearth leaving dark marks, have tried using washing-up-liquid but it didn’t work. As well as a cleaner could you please suggest a sealant as well.
Many thanks
Trish