I have received so many comments on the subject of cleaning slate that I have invited a stone cleaning professional and friend of mine, Andrew Titmuss of Posh Stone Floors to take us through one of his jobs.
Below you can see the job he was faced with, a nice multi-coloured, riven (naturally textured) slate floor which, over time has accumulated a lot of general dirt. The customer brought Andrew in to advise with a view to cleaning and sealing the floor.
- Floor before cleaning
Like most professionals, Andrew insisted on a test clean first. So he set about deep cleaning the area around one tile and paid particular attention to the grout joints. This is what he left for the customer to view. The results were so startling that the customer’s initial reaction was that he must have painted the grout joints, however as he explained, they were just ingrained with dirt, and as in so many cases not just dirt, but several years worth of detergent residue that had built up, slowly over time, so the customer did not really notice the gradual decline in appearance.
Test area – Joints and tile cleaned
Obviously, he got the job and proceeded to make the rest of the floor look like the test area, below Andrew sets out his standard procedure – a procedure which regular readers of my blog will surely recognize:
- Pre wet the floor
- Apply Alkaline cleaner with a bit of abrasive cream cleaner.
- Leave the cleaner to dwell on the floor making sure it does not dry.
- Agitate the floor with a rotary scrubber, scrubber grout joints with a grout brush.
- Leave to dwell, then wet vac up cleaning solution.
- Rinse the floor with clean water making sure all the cleaner has been removed.
- Check the floor to make sure no bits have been missed.
- Leave floor to dry (over night) the apply sealer.
I just want to pick up on and add to a couple of points:
- Pre wetting the floor – this partly wets-out the tile and definitely the grout joint, preventing all the detergent from just being absorbed and therefore keeping it at the surface, where it is needed.
- Adding a micro-abrasive cream cleaner (such as Microscrub) is an option, that can boost the cleaning power of the alkaline, and help to physically scrub the dirt, especially useful on textured surfaces.
- Dwell time is variable but you should look for about 10 to 15 minutes. Keeping it wet in that time by simply adding more cleaning solution. A watch point here is to be careful about all this water when working near water-sensitive surfaces such as kitchen unit end panels (often made from highly absorbent mdf) and adjacent wood floors etc.
- points 4 and 5 are self explanatory
- Rinsing the floor is so important, yet so often overlooked, or even misunderstood: I still frequently come across people who interpret rinsing, as simply removing the dirty water (point # 5 above) that is Extraction not ‘Rinsing’. Rinsing involves adding new, clean water to the floor, with a clean mop, lightly agitating again then extracting , again. – Don’t overlook this.
It is always a good idea to dry the floor after with an old towel or similar, it helps speed up complete drying, so you can seal the floor if required a little sooner, plus it also helps to remove any remaining traces of detergent residue and dirt and eliminates the formation of water marks (especially important on polished surfaces).
If all this seems a little like hard work – well, that is why professionals like Andrew offer this as a service. Remember though that this is an intensive, periodic deep clean – not a regular weekly wash.
Notice also, that very often it is the grout joints that make a dirty floor look really terrible, more often than not, bring the grout joints back to a clean condition will make the floor look like new again.
Copyright Ian Taylor and The Tile and Stone Blog.co.uk, 2013. See copyright notice above.
Is there a product that can be put on the areas where large layers pieces of slate have come off that would make the slate come back to the same color.
WHen my floor was new and pieces were coming off, a chap came in and the product he used brought the color back but I have not been able to find it since.
Caro
Hi Carol,
There are sealers that will permanently darken the slate, if this was what was used before then it will look fine, it should darken the freshly exposed slate layers to somewhere approaching the old.
You appear to be in Canada, you could try contacting Mapei they have a product that might suite here:
Hope this helps
Ian
Wow; this is why I love my job. Just seeing the after picture shows the incredible results that can be achieved. I look forward to reading more.
Hi,
I am not sure if you can help at all. I have a black slate floor in my bathroom. It seems to have water stains on the tiles, which I cannot remove. Is there a product I can buy to fix this at all?. I am based in London UK, some of the products you have mentioned previously I don’t think you can buy here. But any help would be great. Thanks
Hi Laura,
OK, watermarks are marks left by water, or rather what the water (which if pure would leave no mark) leaves behind – so it can be anything including grease, oil, soap etc.
However, given a black slate, and the fact you are in London, suggests that it is just hard water deposits, most water has some impurities, from the chemicals introduced by the water companies to the natural minerals that vary from area to area. London is, if I am not mistaken, in a relatively hard water area, meaning that the water in your area has a bit more calcium carbonate in it. This is dissolved in the water and as the water splashes dry, the water evaporates, leaving behind a trace/film of the now recrystallized calcium (can also be traces of soap etc)
You could try one of two things, wither a gentle abrasive cleaner like Microscrub; this is a calcium based mild abrasive – it acts like an exfoliating cream for stone – won’t damage the stone – this may or may not help but could be worth a try.
Or, you might try a very mild acid based cleaner, use very dilute and DO NOT get one based on HCL – you could try this company http://www.extensive.co.uk – but I recommend that you call them (they are very helpful, and knowledgeable), and ask for a cleaner based on the safer PHOSPHORIC acid, don’t just order off their web site in case you select the HCL based cleaner by mistake.
Hope this helps
Ian
Thank you for your help I will let you know how I get on
Help!
Used slate oil which was several years old on our fire surround for first time and it is extremely streaky and ruins the appearance. Tried WD 40which helped but it is still very marked . What can be done ?
Hi Alan,
OK, you have just applied a thick oil (old) onto a material that is very dense and won’t take it in very easily. The WD 40 is a thinner oil and may have helped thin it out a little but basically you have got oil residue on the surface, hence the streaks.
Suggest you use a solvent based stripper to remove it all. An alkaline cleaner may work, but you may find a solvent easier and faster. when stripped, apply a proper sealer designed for slate I(can be an impregnator or a coating depending on the surface of the slate)
Hope this helps
Ian
Hi, i have recently had a slate patio laid, over the last few days there had been some white spots appearing, it’s not efflorescence or water marks, it’s more like a dots of pva glue. i have heard of this before, having worked with a range of natural stone products in the past, knowing that slate is a natural stone i’m sure it will weather out given time. the truth is i’m not that patient! does anyone know of any good cleaners??
Hi Dave, the only thing I can think of that is lie pva glue, is pva glue, so unless you happened to spill some I don’t think it is that. It could be natural marks in the slate, only becoming noticeable as it dries out. It could be cement/grout spots.
The other thing that comes to mind is a sealer reacting to moisture, have you put a sealer on them? If so then many sealers can react like this if they become exposed to moisture during the time it takes them to cure or set. (some older/cheaper sealers can still do this even after they have set.
Try a micro-abrasive cleaner such as Microscrub, also, try some solvent based cleaner, you could try some clear nail varnish remover, if that removes the spot then it is telling you that a solvent based sealer stripper/remover will .
hope that helps
Ian
Our black riven slate floor is sealed with Lithofin; we have probably applied several layers over the years. The sealant is now showing numerous white marks, some just dots, some a couple of inches long. Is the sealer reacting to moisture? We are now experimenting with removing the layers with LIthofin wax-off so we can start again. Do you have any tips to make this removal job easier/quicker please?
Hi Jane,
OK, it is unlikely to be a reaction with moisture or you would have had it before, but it could be just that layers are building up and maybe this has further reduced the ‘breathability’ of the floor over time, and some any moisture that was previously able to escape, may now be trapped and over time it has exerted a little pressure and created little blisters under the sealer. Or, it could simply be that there are one too many layers on and it will no longer bond – either way not a bad idea to strip back from time to time and re-do
I think that you are using the best product – always a good thing to use the same manufacturers’ stripper. Just follow the instructions to the letter, observe recommended dwell times, these things need time to work, and if you apply it and start scrubbing straight away (as all of us humans are tempted to do) you will be making life hard for yourself; give the chemical a chance to work, strippers need time to soften the sealer, the more time you give the chemical the more it does and the less you have to do do not let it dry on the surface though.
You may have to do it several times, it will slowly work through the layers, this is normal. Rinse well after each time. Rinse REALLY well after the last time, with fresh water, extract that dirty/contaminated water and dry the floor with an old towel (pay particular attention to any crevices in the slate, and of course the grout joints). You do not want to leave any trace of the stripper as this can reactivate when re-wetted by the application of the sealer and prevent the sealer from curing/setting properly.
Hope this helps
Ian
Is there a simple chemical test (preferably using household chemicals) that I can use to tell the difference between a polyurethane sealer and an acrylic sealer?
I ask because we have slate tiles that need to be stripped and cleaned and resealed, and I do’t know what kind of sealer was used last time it was done.
Cheers
Robert in Oz
Hi Robert,
I am not sure if there is but if you can get your hands on some clear nail varnish remover (with acetone) dab some on a cotton wool pad and rub the sealer this will usually have a some effect on a typical acrylic sealer (remove or dull it). Typically polyurethane sealers are much tougher and take a strong commercial solvent to remove them.
Hope this helps
Ian
Hi Ian,
I’ll give it a try and let you know.
Get back to you by the weekend.
Many thanks!
Eight years ago we had slate laid in the hallway, bathroom, kitchen, dining room and utility room. Everything was sealed but (as we have come yo deduce) the utility room. The floor is filthy and I’ve tried everything but having it retiled.
That said I’m excited to read this approach and am anxious to give it a try. Thanks!
Hi Ian,
I see some similar posts, but decided to post my exact issue. I have a slate foyer which had some small paint spots, so I used some nail polish remover with acetone to remove them. I used a very small amount and cleaned with water right after, but the spots grew and created pretty large white stains. Water tends to make them disappear. I tested one with a little high gloss sealer but it’s still pretty visible. I have photos, but not sure where I can post them, but any advice would be appreciated.
Thanks!
Hi Rachel,
OK, what you have done is used a solvent (the acetone) to thin the paint – this is exactly what paint thinners do.
So you have partially removed the paint spots, but also in the process thinned the paint and spread it out a bit.
In theory if you keep going – that is repeat the process maybe once or twice more, each time you will remove a little more paint.
You could try a proprietary paint remover , put a little more on, let it work for a few moments, scrub with a mildly abrasive white nylon pad. Pick up the liquid with absorbent paper towels then rinse well with water and dry. repeat again until all traces are gone,
Hope this helps
Ian
Thanks Ian, I will give it a try!
I have a large expanse light color outdoor patio with slate tiles. I have stains from potted plants leaking dirty water. I have used a power washer on the tile in the past and it seemed to be a bad idea as the water was sloughing off layers of stone. What should I use to treat the stains? Do I then seal it?
Hi Beth,
OK, a lot of slate has very loose layers art the top surface this usually settles down so no more comes off but putting it under pressure from the power washer might keep creating more separation so yes, try to avoid this if it keeps happening.
I would try (in an inconspicuous area) a small amount of cleaner that is based on phosphoric acid or similar as this is what often gets the best results on mineral and rust type marks (often associated with stains from tubs and pots, as the minerals come from the soil). In your part of the world there are a number of manufacturers such as Aqua Mix, and Mapei USA to name just two, who make this kind of product. They also both have abrasive cream cleaners and also alkaline deep cleaners – you could try all of them (just not together)
Once done, you could seal them this would be to help prevent future staining, a good quality impregnating sealer will do the job (those same companies have them)
Hope this helps
Ian
hello – I have the original natural quarry slate tile floor in my Victorian house – the tiles vary in size and colour but most are somewhere between 2 foot square and 1foot x2 feet and some are as much as 4 inches thick . they are large tiles and very rustic. I love them! recently we had a small extension built and the builder ‘cleaned’ the slates and sealed them – except that I cannot get the colour back on them! they’re a mess and I’m at a loss as to what to do. I’ve hoovered them and mopped and steamed them 5 times now and still no change. it’s such a beautiful floor. the builder said to put another coat of sealant on as this may sort out the problem. any ideas?
Hi,
I cannot be 100% sure without seeing them but I can make a number of assumptions:
They are original and probably many years old. Over all that time, who knows what manner of treatment they have been subjected to but it is likely to include, many years of wear and tear (which kind of polishes them), many years of grime and dirt, any number of treatments and polishes that may have included oils and waxes and a variety of cleaning methods and products. All of which builds up a ‘patina’
In cleaning, depending on what he used to clean them, this patina (or much of it) can be removed, and whilst it can be a good thing to do a deep thorough deep clean he has essentially removed that ‘lived-in’ patina that actually is attractive.
In theory this will build up again, but only over an extended period of time.
By sealing it (although you do not say what type of sealer was used) you are actually preventing dirt/grime/ polish/ wax/ oil etc from getting back onto/into the surface so it will prolong the ‘new’ cleaned look until the sealer breaks down. So, most likely, adding another coat of sealer will not help. In fact it will be doing it’s job by preventing this from happening.
Now that the slate is sealed, what happens when you wet the floor? – presumably the sealer keeps a good deal of the water out, and prevents ‘wetting-out’ of the surface- so you do not see much change.
If there are any areas where the sealer is not present, and the slate wets out and goes darker, this might be more to your liking.
It follows then that you might prefer to strip off the sealer and do ‘something else’ to artificially restore the floor’s old patina. This can involve using oils like boiled linseed and or wax. Or a modern sealer that is designed to enhance the colour.
Although even doing one of the above may not get it back to exactly the way it was, you have removed a lot of ingrained dirt (which is desirable). But it may get it to something more aesthetically pleasing than the super-cleaned and sealed (and by the sound of it, dull and lifeless) look you have now.
Be warned though that oil and wax are not always easy to apply, and they do not last (in days gone by the floor may have been treated in this way on a regular basis until such a point that it builds up an impenetrable surface, this would have been quite a chore). A modern enhancing sealer can be easier (or at least involve much less upkeep and maintenance) but the floor would have to be uniformly and evenly stripped to ensure even application and avoid a patchy appearance).
Hope this helps
Ian
hi ian
Thanks for responding. The sealer used was thompsons clear water based clear silicone sealant. The tiles are from 1911.
When the tiles are wet they look like they used to. Lovely darker colour with a little shine. When dry they are very dull and pallid in colour. There are definitely some areas where the sealant has been absorbed.
The reason for sealing the tiles (they haven’t been sealed in the 15 years I’ve lived in the house) is because I’m due a baby very shortly and dread the thought of little tiny feet turning black in the kitchen!!!
Thanks again for your time and energy in replying
Andrea
Hi Andrea,
OK, well that product is more of a water repellent than a stain resisting sealer, plus if the slate darkens quickly when wet then it is not really doing much resisting! – so in order for that sealer to be effective it most likely needs another coat, OR the slate is so dense that it did not take much sealer in in the first place..
In order to achieve the all over dark look you would need either the old fashioned method of oiling the floor (not fun, practical or easy), or use an enhancing sealer but to do that you would have to strip out the existing sealer 100% – perhaps Thompsons can advise you if that is possible?
Regarding preventing black dust coming off the slate onto baby’s feet – no impregnating sealer is really going to do that, you would need a coating and that is another system altogether and usually puts a shine/gloss on them – plus it will need regular re application
Hope that helps
Ian
Hi Ian
You’re a superstar for replying- thank you. I had pretty much resigned myself to oiling being the main method I might need to do!
You mentioned about a coating? Can we DIY this or do you recommend professionals?
Thanks once again. I’m very appreciative of your generosity.
Andrea
Hi Andrea,
There are various coating sealers around but the same issue applies – you will need to strip back the current sealer first.
A coating sealer does what it says, it coats, i.e sits on the surface and leaves a coating between the feet and the surface of the stone, so it can make the slate easier to keep clean, and because you are walking on the coating, not the slate, it will help reduce dusting (although that is not its primary function). However for it to work you need a surface that is both textured and porous – so that it can bond. the sealer you have put on will have adversely (though not entirely it seems) affected the porosity, so it will need stripping. If the texture of your slate is very smooth, then again a coating sealer may struggle for grip. Even if it does bond, you have to be prepared to top up or reapply every once in a while (anywhere from once every 6 months to once every 3 years depending on traffic and cleaning regime) but still easier than oil in my opinion.
There are a number on the market by Lithofin, HG, LTP and others.
Easy to apply DIY the slightly trickier part is stripping back the old sealer.
Hope this helps
Ian
Hello,
I was wondering if you could help me please. I have mosaic slate tiles in the kitchen of my rental flat and the previouse tenats have not wiped them well after cooking. The whole area behind the hob is darkened with grease. Is there anything that you could suggest I do to bring them back to their former glory?
Many thanks, Susanne
Hi, Susanne,
Slate is pretty impervious and will really only be holding the grease at the surface, if it has also been sealed then even more so. The grease just clings really well as it will also to the grouting. I would try a high pH degreaser – there are several on the market including one that I manufacture under the All for tone range here in the UK. Follow the instructions and rinse well after and you should be able to remove most if not all of the grease.
if you search for this string on Amazon ( I cannot put live links in here it affects the site ranking) you should find it
Hope this helps
Ian
Heavy-Cleaner-Xtreme-Stone-1Litre/dp/B0073EEI0E
Hi Ian,
Thanks for all this helpful info above.
I have a very specific question about a wet room floor. It’s a rough Brazilian slate, laid 10 years ago and sealed with lithofin. There’s a low temperature underfloor heating system in the screed below.
Here’s the horrible thing: even though the floor is cleaned regularly, for the last few months there is a nasty smell after the shower has been used! It’s not the drain. We’ve tried steam cleaning and using biological detergent (rather than our usual gentle floor wash) but to no avail. Do you think the slate, or maybe the grout has become porous to bacteria?
Would be so grateful for your input.
Hi Connie,
OK, well really that could be coming from anywhere – you are going to have to be like a doctor and go through a number of scenarios. First of all, are you 100% it is not the drain? Just disinfecting the shower outlet may be giving you false info. The shower trap may be clean, but there may be an issue futher down the line, maybe there is a leak in the trap, thus allowing air to transport smells up from the drainaige system – you only get the smell when you use the shower? The shower water disturbing things and causing the smells to come back up? I doubt the tile surface is holding bacteria and even if it or the grout is, it would most likley be present all the time and I doubt it would smell like a drain.
One other possibility is that if there was some break inn the seal (I mean the silicone seal between the walls and the floor) allowinng water to get in and under the slate tiles, and if there are somme voids in there or the slate has moved, come away from the subfloor in places then this could be a source of the bad smell, dark, dank crevices beneath tiles holding water that is stagnant, gently incubated by the UFH, then this could be a like a giant petrie dish allowing he bacteria to flourish. Then when you turn on the shower it gets flushed and the smells come up. Hard to check for this unless you can tap around to listen for any signs of delamination, sometimes by pressing on the tiles it can cause water to ouse up thus revealing where the loose tiles are and where the water is getting in. If this is the case then you would have to carefully lift any loose ones, prepare the bed (remove adhesive) and allow it to thoroughly dry out before replacing the slate and regrouting and sealing.
Hope this is of some help
Ian
Hello Ian,
We have had a new slate floor laid in a new build, it has not yet been sealed. It is grey but sadly there is a lot of builder’s dust/ impregnanted white dust and now (after mopping) this is more like cement in the fine surface ridges etc of the new slate. I am struggling to clean this. All my washing and scrubbing tends to leave the slate cloudy, there are areas of more pitted whiteness into the surface which will not brush out dry or wash out wet. Should I get a professional to use a large scrubber machine… I want to get this slate clean again before sealing.
I realise we should have covered it whilst builders finishing their work, but too late now. your advice would be greatly appreciated,
Hi Rebekah,
Ok sounds like ‘normal’ builders film – dust from plaster etc, but also more than likely there will be some grout haze/residue that you have not noticed until you came to clean it. It is very rare for a new slate floor to be left absolutely free of cement haze, especially in the pits and crevices.
It is typical to need an acid based clean after this – there are some cautions though: 1) Use only a safe acid cleaner, designed for the job, NOT a brick acid 2) make sure the grout is at least 3 days to a week old before acid cleaning – you should be ok here I think) 3) ANY acid wash creates the likelihood of lightening/etching the grout joint itself – with a natural grey grout this is less of an issue, it just goes a little lighter – (for a while) but if you have a darker grout, one that was pigmented then it can bleach out some of the colour. 4) You have to use them correctly – following the below procedure:
1) Pre wet the surface
2) Dilute the acid based cleaner appropriately – the weaker you can get away with the better – do not think stronger = better/faster
3) Apply, leave to dwell for a few minutes BUT – NO NOT ALLOW to dry out
4) Agitate/scrub with nylon scrub brush and or white nylon emulsifying pads (on occasion more coarse pads could be used (red, blue, green even black) but test they do not scratch the slate first
5) Pick up the dirty solution BEFORE it has a chance to dry on the surface – hiring a small wet vac makes this really easy but can be done with a good mop an bucket
6) RINSE WELL – this is not the same as #5 – this means after # 5, add clean, fresh water to the floor – lightly scrub again with a pad or a nylon brush ( standing with a nylon bristled broom is fine for this) – a light agitation of the rinsing water on the surface of the stone followed by
7) pick up the rinse water – again a wet vac makes this easy – DO NOT SKIP THIS STEP
8) – buff the floor dry with an old terry towel
9) Allow the floor to dry out fully, that means until the grout joints go back to their dry/ lighter colour (and they may be even lighter now), this is because any cement stains still there will also dry ‘white’ and be more noticeable than when the floor is wet. Hopefully the above procedure has removed all or most of the issues but if not, repeat the entire process.
#’s 6, 7 and 8 are so important as they help make sure there are no traces of acid cleaner and any remaining dirt residue left as when the floor dries out these will show up as white marks again.
All of the above is not rocket science, I a sure you ca do it, hiring a wet vac, and if you can a rotary scrubbing machine with a nylon brush head or pads would also help.
You can also get a professional in, as long as they follow the above – but that will cost a lot more of course.
One other issue you may have is if the cement involved was heavily polymer modified then this can impact on the effectiveness of an acid cleaner – so you might want to do a test first.
if you want some suggestions on a particular product, you could message me directly via the contact us part of the blog.
Hope this helps
Ian
A scrubbing ma
thank you Ian, I hope this works,
what acid based product would be advised please?
Rebekah
Hi Ian
We had the walls and floor of a large walk in shower in our 17th century cottage tiled with grey slate mosaics in 2010. The mosaics were sealed at the time by our builder/tiler. This shower has not been in regular daily use as we have two other showers in the house that we use on a regular basis. About a year ago we noticed a small number of the mosaics on the wall behind the shower head were beginning to turn a reddish brown colour. At first we didn’t worry too much but in the last month or so we have started to use this shower more frequently and the areas of reddish brown discolouration are getting larger. We assume this is caused by lead in the mosaics oxidising and ‘rust’ coming to the surface. Do you think this what it is and if so how can we stop it spreading and then clean up the areas that are already affected.
Regards, Gary.
HI Gary,
OK well it is more likely to be iron not lead, some slates do have iron bearing minerals in them which will oxidise to rust as you say – however there is another possibility and that could be a kind of red/brown mould/mildew – both need moisture to form.
Do a test with some mild phosphoric acid based cleaner if you can get some (contact me on the contact us page if you want help there) but you could do a quick test with vinegar – see if it removes the brown, IF it does then it could well be a rust type stain and the phos acid cleaner would be the way to go.
Also try a dilute household bleach on another area – if that works then it could be mould – in which case treat the whole slate that way, for both, rinse well with clean water after and allow to dry well by keeping the shower door/curtain open and open a window, leave the fan on etc – whatever you can do to facilitate the faster more efficient removal of moist air.
Hope this helps
Ian
Hi Ian,
We have just moved into a house with a large back garden completely paved with what I think is grey slate (I’m not very good at telling these things!). Over the winter, the slates took a bit of a battering with the weather and now look tired, dull and dusty. This was not helped by the floor not being level meaning one large puddle forms in the middle and creates green moss marks.
This weekend just gone I cleaned the whole floor for three hours using a power washer (Karcher patio cleaner). I used the yellow round T350 attachment. It got rid of a LOT of grime/dirty water which I had to constantly sweep away to the sides but when it all dried it still looked dusty. It also took up a lot of the grout and sand underneath unfortunately.
How can I properly clean it with a product that does more than just water? The karcher has a tube that can be fed into bottles of detergent so you get a mix of water and cleaner. Ideally I want the ‘wet’ look as when wet the floor looks great (darker and polished), but dry it looks dusty. Is there a sealer or enhancer or even both I should be using? How often does it need to be done as it’s a BIG area?
Ideally I’m after something that doesn’t make it too slippery as the wife is 7 months pregnant!
As for the grout which I will have to redo in places, is there anything you recommend? I’m guessing the original grout was light grey but it’s now very mossy so hard to tell.
I really appreciate your help in advance as I’d love to be able to restore the garden to its former glory. I can send more detailed pictures if you let me know where to.
Thank you!
Hi Daniel,
OK, there is a lot going on there. First of all the type of stone makes a difference. It could well be slate, but it could be black limestone also – or something else. Black limestone is popular and can actually fade and go dull, slate can just be dull anyway.
There are cleaners that you can use I conjunction with the machine. But which type may depend on what, exactly you are trying to clean. Have you still got green algae/moss? Have you got black marks? is it just grime? .
As for enhancing – this is possible, most enhancers are impregnators also – meaning they sit below the surface and should not impact in slip resistance. However most also require stone that has not previously been sealed with anything as the presence of old sealer, even just traces of one, can prevent the enhancer from giving an even effect. So, you might want to check that first. I also note that you mention the cleaning process has removed sand from below – you ought to resolve this I think before doing anything else.
Hope this helps
Ian
Hi Ian,
I sealed the floor with a Lithofin product a couple of years ago and it looks quite terrible now. I was advised to take of the sealer and apply a new sealant in fact LTP Colour enhance an sealer. I was also advised to use the LTP stripper to take off the Lithofin sealer. It’s an acid based stripper. I’ve done this. But the floor still looks quite dirty. Should I use the LTP stripper again or might this be dissolving some of the grouting and spreading over the slate floor? What product would you advise me to use to try and give the slate a final clean? I don’t have a rotary scrubber. Is there something suitable on the market which is not too expensive and not really big….maybe something hand held? Thanks. David
Hi Dafydd,
OK, I have gleaned from your two messages that the floor is slate, however, you have not said what type of sealer is being removed.
I am going to make a guess that you have a topical sealer that you are trying to remove (having said that much of what I am going to say is universal anyway).
The reason I have guessed at a coating sealer is that they are more common with slate and give a surface sheen, this wears off over a relatively short time and so degradation is more noticeable than for say an impregnating sealer. Coating sealers will also wear unevenly so you begin to see a dulling. Patchy appearance and going from a slight sheen or gloss back to a matt finish is very noticeable and can make the surface look dirty.
OK, I understand the reason for wanting to remove the sealer – and it appears that you have been recommended to use a stripper, but it has not given you the look that you require. Two things to think about here: one is that stripping back a shiny coating the natural surface can leave a floor looking dull and lifeless (that is one of the reasons for using a coating sealer in the first place, to give the surface a visual ‘lift’). If this is the case then I understand that you now wish to do something with it to reinstate that finish, and you have mentioned an enhancing sealer as an option (I will come back to this, it is not straightforward). The other thing to think about is that it is highly possible that the coating sealer you have, even though worn, will require more than one attempt at stripping. In fact, it is quite common for a floor to look worse after the initial stripping as the stripper may have taken perhaps 50% to 80% of the sealer off (killing any sheen in the process) the residual sealer that is left behind is now damaged and can create a more grubby/patchy appearance. This is normally solved with a second stripping operation.
It is also possible that removing the sealer may reveal some other issue that was masked by the sealer (such as grout residue). In other words, there may be some underlying dirt or contamination. From the picture you sent, it is not clear to me which of the above it could be, but a quick test will help to find out.
Regarding the stripper being ‘acidic’ and causing potential damage to the grout: I do not know precisely which product you have been using but most strippers are not acidic (acid-based cleaners are usually reserved for removing cement/grout haze and other mineral type contaminants).
If you have just seen the list of ingredients containing something like ‘silicic acid’ then it may not actually result in an acidic product – that will depend on the precise mixture of other ingredients. So, the acid content may well be buffered or there for some other reason (I am not a chemist, but just because a product may list an acid in the ingredients, does not necessarily make it an acidic product). Most strippers are solvent-based, and lastly, most proprietary grout haze removers contain acids that are designed for the purpose of removing grout haze without causing too much additional damage to the grout joints themselves are going to have much more and stronger acids than this.
OK, there are a number of things to test/try:
1. First what happens when you wet the white/hazy residue? Does it temporarily disappear, or does it retain an opaque appearance that is noticeable through the water? If it appears to go translucent and disappear then it could be more likely to be cement residue, if not then more likely to be residual sealer that has ‘gone white’ as a result of the partial stripping.
2. Try some more of the stripper you have been using, place just a capful of the stripper on a part of the slate where there is a lot of the white staining and leave it to dwell for about 15 minutes (don’t let it dry). Scrub it with a nylon scrubbing brush or white nylon pad, pick up the solution with absorbent paper towels then rinse well with water. Allow it to dry. – has it removed the white marks? – if so, this is an indicator that you need to do a second stripping operation (and it should not harm the grout).
3. Try a grout haze remover – there are several on the market, but make sure you go for one based on phosphoric acid or similar and NOT one based on HCL or any product described as a brick cleaner. I have a product (but there other available as I have said) called Grout Haze Plus which would do the job. Take a capful of the product neat (this is just for the test, you would not use it neat in practice) pour it onto another slab where there is white staining. Watch closely and look for effervescence (tiny bubbles or ‘fizzing’) if you are not sure what you are looking for, move some of it onto a grout joint, provided there is not still a significant layer of sealer on the grout you should instantly see a bloom of white bubbles appear (this is fine, it will neutralise itself pretty quickly but you can just rinse it off with water to stop it). If you get no bubbles there, then you have got something on the surface of the grout – i.e. sealer or a heavily polymer modified grout. Try rubbing the surface of the grout with something sharp and metal – just to expose fresh grout – it should fizz now. OK, if you get fizzing on the test patch on the slab – it is telling you that there is something mineral for the mild acid in the cleaner to attack – most likely cement/grout haze – and a grout haze removing product such as this will be required. If you get absolutely no fizzing on the slab even when you agitate the surface, then sealer residue is more likely (and test #2 above will hopefully prove that).
Hopefully, that will help you get to the bottom of the issue and allow you to get back to a clean, slate surface. Regarding low cost, smaller machines: I am aware of some small, hand-held scrubbers (some of them are cordless) but I have never tried any of them. You can hire the industrial ones from most hire shops, and also, I would suggest either hiring a wet vac or buying a small/domestic one they make such a difference to the clean-up. After this, you wish to re-seal in order to put back some stain protection and bring back an attractive appearance.
You mention that you have been advised to use an enhancing sealer – I would advise caution. The reason I say this has to do with the way enhancers work; they need to penetrate the surface to the right depth and they need to do so evenly, in order to correctly alter the way light is reflected back out of the stone. The problem is that it is usually best to use enhancers on new, previously unsealed stone, as it is can be very hard to guarantee total and more to the point, even stripping of previous sealers. When stripping sealers with the intention of reapplying the same type or other non-enhancing sealers, it does not matter if there is some residual sealer left in/on the stone, sealers are designed to fill or line pores in the stone and so if some pores are already filled with previous/residual sealer – it is not a problem, the new sealer just goes where it is needed. So, although the floor may visually appear to be 100% stripped (and water drop testing may seem to wet out the stone well) in reality there can be a lot of sealer residue left in the stone. This can prevent an enhancer from getting where it needs to go – the result can be a very patchy effect, with the enhancer working well in some areas and not at all in others. Personally I would want to be 100% satisfied that I have removed every possible trace of previous sealer before I tried using an enhancer, wetting the entire floor and trying to see if there are any areas that don’t appear to wet out properly or as much (don’t darken as much or as quickly) can be a good indicator of traces of sealer residue but a lack of them is not a complete guarantee. You might be better advised to get the floor surface as clean as you can then reapply the same kind of sealer that you had before. If my guess is correct ant that was a coating sealer, then I would recommend this as enhancers would not reinstate any surface sheen either.
Lastly, I hope this has been of some assistance.
Ian
Hi Ian,
Thank you for the advice. I tried out your Grout Haze Plus and it worked a treat. I think the HCL based stripper for stripping cement stains you cautioned against using (in a further email to me) was making matters worse. It looks like it was indeed breaking down some of the grout in the grout joints and spreading it across the slate surface making it look even worse than before. Yours phosphoric acid based stripper has cleaned up the mess. I’m very happy indeed. Thanks again.
Dafydd
Thanks for the feedback Dafydd, glad to be able to help.
Hi, I have just had my patio finished, it is Marshalls Casarta Brazilian Slate (Grey/Black) My problem, is that it is completely covered in dirty marks. While it was being laid, there was naturally mud and dust around, general building mess and i was just assuming that once completed, i would be able to just give it a good brush, followed by a once over with the pressure washer and my new patio would look fantastic…….. but it doesn’t and im absolutely choked as its cost me a fortune. I have since given it another brush, another jet wash… (not much change) I then used soap and water and gave a good scrub with a firm broom… but alas, it still looks the same. While its wet, it looks absolutely fantastic, but within 30 minutes, its dried out and looks awful again…. Please help …. Thanks in advance, Dean
Hi Dean
Ok from what you describe, (looks ok when wet but not when dry, your cleaning method so far not worked) seems to suggest building stains most likley cement.
Is the patio grouted/pointed?
I think I would be trying a mild, SAFE acid-based cleaner. By this description I DO NOT mean brick acid (which usually contain HCL and are not something I would recommend) .
Ours is called Grout Haze Plus (based on phosphoric acid) it works on very thin layers or films of cement haze at a time so can take more than one application (but we do not want to damage any of the cement ion the joints).
You would need to test it for sure, a) to see if it is going to work and b) to make sure your particular slate does not react (most slates esp darker ones are not really acid sensitive and so should be fine, but it is always a good idea to test first, if you have a spare piece that would the best thing to try it on.
You could try to get an indication if this is going to work by first trying some white vinegar on a small trial area.
Feel free to send me a picture if you have one – it may help confirm my thoughts
Hope this helps
Ian Taylor
Thanks very much Ian. Yes the patio has been pointed (well, 85% of it has) it’s being finished up tomorrow so I need to leave it for a few days until that has all set properly. I will send a photo, but I can’t see how to attach one ?
Regards
Dean
OK, no problem, yes you need to give new cement at least 5 days more if yu can (some would say double that) before you go throwing any chemicals at it)
you can try sending a pic via my other site https://www.allforstone.co.uk/contact.html
Hope that helps
Ian
Hi there.
I have recently started a job to tile my kitchen. I has some nice slate tiles that i had stored outside for number of years. They were good quality calibrated tiles from Fired Earth. Urban Black Grey is the product. I decided to wash them down with a gentle power wash. I let the water dry off and almost every tile is covered in white patches. I tried washing again and drying quickly. No luck! till white marks everywhere.
I tried cleaning with a a solution of lemon juice, bicarbonate soda and vinegar which has reduced the amount of white very slightly.
I believe this is a mineral residue. It is almost like a calcium build up – not too sure.
Can you recommend a product that will easily remove these white stains/build up? I have 40 400×600 tiles to clean and if I keep going with the home made solution I will be here for a year cleaning.
Your help is appreciated.
Hi Ian,
OK, it does sound like mineral deposits, the slightly acidic cleaner you are using (vinegar and lemon juice) is doing something. However, it is not going to be strong enough. Also, the addition of bicarb is doing little to help, in fact, it is probably hindering: The bicarb is a base and will react with the acids – they will basically neutralise each other out, thus reducing any cleaning power the acids may have (they are reacting with the bicarb before they get a chance to react with the calcium deposit on the tile), thus the cleaning effort is being diffused and diverted away from where it is wanted. Second, as a result, other white ‘salts’ are produced such as sodium acetate – which may leave a white coating of their own.
Lemon juice is acidic and may help but it also has lemon oil and other things in it which may not help at all. I would try using the vinegar (if it is white vinegar) on its own: Dampen the surface with water first then rub a little vinegar onto a small test area, leave a for a moment, then rub with a white nylon pad – then rinse and allow it to dry – if this gives a better result than your first attempt then it backs up the idea that you need to remove mineral deposits, and that you should look for a stronger product.
From our range, I would try Grout Haze plus available here available in 1 and 5 ltrs. This is a safe cleaner based on phosphoric acid, NOT HCL (do not use a brick acid). HOpe this helps
Ian
Hello, I have read through the article and comments posted here so hoping you can help. Four years ago, we purchased an existing home with blue slate flooring on the majority of the first floor, though we don’t know when it was installed. It had a slight sheen, not gloss look to it. It has dulled over time even though I have done the lighter cleaning methods using water, and/or bona stone floor cleaner. I asked a professional company in today to deep clean and/or revitalize it and he cleaned a sample area to show result expectation. He used a fluffy product and sprinkled it on the floor, then used a machine with soft rollers to roll over it the area. The result looks like he removed the sheen and while the grout looks lighter/cleaner the color of the tile went dull, which seems like it removed the sheen sealer and is now in the bare form. Is the cleaner he is using ok, and I just need to add a sealer to enhance the color back? Or is his method not good, and I need to go another direction? Thank you so very much