How To Seal Terracotta – Step By Step
By Ian Taylor on Dec 6, 2008 in Terracotta
Back in the 1980′s there was a bit of a craze for using terracotta. It was everywhere, in magazines, on TV, and it was soon being used extensively in homes and also in commercial properties like pubs and wine bars. After a few years it seemed to disappear almost as fast. This is due in part to the over-exposure and the ever changing fashions for interior design, but I also suspect that more than a few people experienced a number of headaches in terms of sealing, cleaning and maintaining it.However, all things work in circles right? Well not exactly, but I do see that Terracotta is making a little bit of a come back, not like the last time, but people are it seems one again being swayed by the rustic charms and warm tones and using it in selected areas.
So, I though it timely to do a little article on the methods for sealing terracotta. There are basically two systems (and lots of variations for both) :
1. The traditional oil & wax treatment, or,
2. The modern, synthetic approach.
1. Traditional Oil & Wax.
Many Tilers still prefer this method, largely I think because this is the method they were taught. One of the most popular methods for sealing terracotta is to use a combination of boiled linseed oil and then polish with a neutral Beeswax.
First the tile is treated with several coats of boiled linseed oil; the oil is spread with a cloth or sponge as evenly as possible over the terracotta, before grouting. The first coat is the hardest as the oil is pulled into the extremely porous tile very quickly, so it takes a bit of skill and practice to get an even coat. Subsequent coats are a little easier, until the tile approaches saturation. Care must be taken not to over-apply the oil, making sure any surplus is not left to dry, as this would become sticky and require scraping off. Once the tile is sufficiently sealed (it will take several coats) it will also be considerably darker. It is the oil that gives terracotta that characteristic amber shade that many people like. Once dry, they can be grouted. When the grouting is completely dry, the tiles can be finished off with a coat or two of wax polish – there are many to choose from, some in paste form that require thinning with white spirits (a messy job) and others that come ready to use as a ‘floor wax’.
The advantage of this system is really just aesthetic, if you like that ‘warm look’ then go for this. However, there are several drawbacks: It is a much more involved process in the beginning; ongoing maintenance is also more arduous, the wax will quickly dull through traffic and cleaning, thus it will require frequent re-polishing and this is a hands and knees job, unless you are prepared to purchase a buffing machine. After a while, the wax will build up in layers and will start to actually attract and hold dirt, becoming darker and even tacky to the touch. At this point it needs stripping off, right back to the tile surface using solvent stripers (the oil will not be removed) and the whole polishing process starts again.
2. The Modern, Synthetic Approach
While possibly not offering quite the same depth of colour as oil and wax (it should be pointed out that not everyone likes that artificially darkened colour anyway) is much simpler and far easier to maintain. Again there are several propriety products available but one of our favourites is Seal & Finish Low Sheen. Seal & Finish Low Sheen is a safe and easy to use, water-based product. Actually it is two products in one, a sealer and also a low-sheen polish, this saves both time and money. Several coats of Sealer & Finish low sheen can be applied to the tile, depending on its porosity and the degree of sheen you are after. After grouting another coat may be applied. And that is it, job done. As it is a surface coating, just like wax it will of course wear, but it is more resilient and will not dull quite so quickly. With proper care, using neutral cleaners it can actually last for up to 3 years, but typically will not require any topping up before 12 months (this is dependent on many things of course). When it does start to dull down, there is no need to strip; instead a fresh coat can be applied right over what is already there.
If a very glossy finish is required, like a highly buffed wax, then adding a coat or two of Floor Shine & Hardener will add that high-gloss look. In addition to this, it also acts as a sacrificial layer, protecting and prolonging the life of the sealer beneath. Floor shine & Hardener can be re-applied as often as required, again without first needing to strip previous coats.
Incidentally, both Seal & Finish Low Sheen and Floor Shine & Hardener look great on textured slate and even sandstone.
Keith Elms | Aug 24, 2009 | Reply
I recently bought a property which has had terracotta tiles laid on the patio area. They have not been treated and I would like to paint them with masonary paint. Is this feasible?
Rosemary | Mar 8, 2010 | Reply
I am renovating a very old terracotta tile floor in Italy. As I do not want a very shiny finish I was thinking of doing the linseed treatment, but your Seal & Finish Low Sheen sounds very attractive. Don’t suppose there is any chance that I can buy it here in Italy, or in France?
Ian Taylor | Mar 11, 2010 | Reply
Hi Rosemary,
Seal & Finish Low sheen is a great, low maintenance alternative to oil and wax (I do like oil and wax also, but there is more work involved both initially and ongloing). There are not distributors in either Italy or France at this time but there are several in the UK who can ship to you, and also in Germany. if you send me an email I can put you in touch.
Ian
Marshall Spevak | May 28, 2010 | Reply
I stripped, sanded and cleaned with a brillo type green scrubby our satillo tile. I also sanded the grout until it was white. It got pretty wet. My wife wanted to seal it within a day and did. I noticed some of the sealer in the grout was wet after everything else was dry and some of the grout was dark like it was still wet under the sealer. How long should I wait for the tile and grout to dry before I seal. Thanks.
Ian Taylor | Jun 1, 2010 | Reply
Hi, drying times can depend on the sealer and a number of other things, he porosity of the grout and the temperature and humidity of the room etc. But the grout wants to be as dry as possible. If you can get a damp meter, you should be looking for the scale to be showing less than 10 to 15% moisture content, or be in the ‘green’ section. If your sealer is a good quality one then it may be breathable and the grout should dry out anyway, it may just take a little longer.
Hope this helps
Ian
Sona | Jul 14, 2010 | Reply
Hi, I am from South Africa and do not suppose that I will find your products here, but if you could assist me with some knowledge I’ll appreciate. I recently installed some Mexican terracotta tiles in my kitchen area. When buying the tiles, I was told to seal it with a mixture of raw linseed oil and terpentyne (a paint thinner). When I asked “how much?” I was told “till it is full”. The tiles now have 4 layers of this mixture on and I added 5 more in an area where I want to place the kitchen units just to give the tiles some form of protection underneath the units. I can see that it is not nearly “full” yet, but I also do not know WHEN it will be “full”.
Unfortunately I only decided this morning to learn a bit about this before continuing.
My questions:
1. what will the tiles look like and do when it is “full” so I know when to stop? Currently it looks like I am going to need about a cup full of the mixture per tile?
2. should it be raw or boiled linseed oil and what is the difference?
3. Can I switch halfway to a commercial sealant?
Sona | Jul 14, 2010 | Reply
Last question: I like and want the dark colour the oil gives. So can one use the oil and then use a commercial sealer instead of wax?
Ian Taylor | Jul 14, 2010 | Reply
Hi Sona,
There are a few questions there:
How do you know when it is ‘full’ ?- basically the tile will stop taking in any more oil. The best thing to do is to apply the oil , allow it to penetrate, then rub it in well and be very careful to remove all excess BEFORE it dries – this is just like using an impregnating sealer.
Then, leave it for a while, I would suggest at least one hour but preferably longer, this is to allow it to set and harden, if you keep pouring more oil in while the last coat is still wet, all you do is push it deeper into the tile.
At some point, and I would think you must be very close to that now, the oil will will not soak in any longer, when you pour some on, it will sit on the surface and not darken it any further. If you leave too much oil on the surface it will dry as crystals – a bit like how honey goes wh it gets old – you would need to carefully scrape this syrupy residue off with a plastic scraper.
Raw or boiled? – not sure I fully appreciate the difference, but typically, in the UK at least we use boiled. From my experience boiled is relatively easy to use and does not normally require any additional thinners. However I would not change halfway though.
I would not add more in the kitchen areas, if you do it will look darker. I would treat all areas the same, when it is fully sealed, it is fully sealed, period.
Regarding your last two questions, no, I would not switch, you will not easily remove the oil now that you have started, and as you like the shade it gives why bother?
We have had some success in using a modern wax alternative as the top coat/polish instead of using natural wax.
The oil gives the tile its colour and deep stain protection, the wax gives it a surface coat and shine. Normally wax like beeswax is used over the oil. The Oil wax look is very appealing as it adds rich warm tones and can look nicer and nicer with age. However, it is a lot harder to maintain than a synthetic coating. You could finish the oil phase, let it completely set for a day or so, then try something like Aqua Mix Floor Shine & Hardener – a high solids, acrylic polish – easy to apply as it is water based, add as many coats as you like, the more the shinier. As it wears just top it up.
With wax, you first have to apply the number of coats to give the desired finish, then the wax needs to be buffed, preferably by machine. Then almost immediately, it starts to wear and dulls down. You can top up the wax, just like FS&H but you have to buff each time. After a while (a number of top ups) the wax builds up to a sticky layer which can attract dirt and the floor then starts to deteriorate in appearance, (getting darker and grimy). This necessitates stripping back the wax, (as far as but not including the oil) and starting again.
There was a supplier for Aqua Mix in SA, but I am not sure he is still operating – I will check and come back to you though.
Hope that helps
Ian
George | Jul 19, 2010 | Reply
Hi, about 4 months ago we put terracota on our fence walls but we were reccommended to use a mix of cement and sand as the grout. Well, the cement has make the terracota color very dull. I used a product called LPC-85 and some color is back. I haven’t finnished the whole fence because instructions says that terracota has to stay wet for 5 minutes which is pretty hard since it absorbs the liquid almost right away. I want to know if you have any advice in what I’ve done already or whatever is ahead to bring back the color and to seal them after. I haven’t looked for your Seal & Finish Low Sheen product here in Panama (Central America)but first I would like to read your advice.
George | Jul 19, 2010 | Reply
P.D.
LPC-85 is an acid solution that acts as a cleaner before using any sealers. Its main ingredients are hydrocloric acid 20%, phosphoric acid, nonionic surfactant.
Ian Taylor | Jul 19, 2010 | Reply
Hi George,
OK, clearly you have cement bluhm or haze. This has happened because you have grouted the terracotta without sealing (at least that is what I am guessing). That cleaner is pretty aggressive so be careful, anything that contains hydrochloric acid should be used with caution. It will also lighten the colour of the grout, so if it is a dark colour, it will be lighter after you acid clean it.
Regarding keeping the tile wet for 5 minutes: firstly I would recommend pre-wetting the surface – really saturate the tiles with water (this may kick off some efflorescence but that can’t be avoided at this stage), this will mean that the tiles do not suck the acid cleaner in straight away, and so help keep the cleaner where it is needed, at the surface.
Also, put the acid in a spray bottle and keep spraying it over the the 5 minutes (where suitable protective clothing of course!). Then scrub or agitate the tile with a scrubbing brush or pad. Rinse down and repeat – maybe a couple more times. This may be a slow process but there is no real alternative.
Also, I guess it gets pretty hot where you live, so do this early in the morning or late in the evening.
Regarding the sealers, I am not sure what is available in your region, but there was a distributor for Aqua Mix in Mexico: http://www.aquamix.com.mx/aqua_van.htm
hope that helps
Ian
Sarita | Jul 31, 2010 | Reply
Hi Ian,
thanks for so generously sharing your expertise, I appreciate it.
I want to find a solution for my elderly parents, who many years ago had a terracotta floor laid in their kitchen with no seal (disaster!). The tiles are large, mid-coloured yellowy-orange, and show EVERY mark of food, oil etc. My 81 year old mother regularly martyrs herself scrubbing these off which kills her back, and it’s a crazy situation, perpetuated by the days and days of drying time that the process of cleaning and sealing the floors would apparently take. On poshfloors’ website they say 3-4 days in one para and 10 days in another. 3-4 days, well, maybe I could arrange to be here while they go away; but 10 days – forget it. My father is too unwell to be away for that long.
The tiles are currently rather patchy looking s there are big bleached-out marks where my mother has scrubbed them with HG Cleaner; and still some residual oil stains here and there (in the middle of the bleach marks, often! nicely highlighted
).
Is there any solution other than getting them deep cleaned, with a long drying time, then sealed?
How long a drying time should I estimate?
And how long would you guess the seal would take to apply & dry? (its a largish kitchen and there’s a small hallway and small utility room which are also tiled)
Can the floor be walked on at all while it’s drying? Or is there too big a danger of marks?
I presume you can’t walk on the seal while it’s drying?
I ask now as my folks have just gone away for 5-7 days (depending on weather) to Wales… so perhaps I could just get this done while they’re gone!!
The only thing to mention is that the resulting floor seal mustn’t be slippery (my father is very unsteady on his feet.)
Thanks in advance for your thoughts on this,
Sarita
Ian Taylor | Aug 2, 2010 | Reply
Hi Sarita,
OK, quite a few issues there!
First of all, I sympathise with your situation as unsealed terracotta is not the easiest thing to live with in a kitchen, for anyone, let alone someone getting a little elderly.
There is no quick fix I am afraid, but regarding the drying times, there are things that can be done. The issue of drying times really comes form the traditional type of sealing, using oils and or solvents – you simply cannot put a oil based treatment or some of the older solvents onto a floor with any moisture – it won’t let the the oils/solvents into the tile so you get a blotchy look and also other weird effects like the sealers going cloudy etc. Modern water based systems are not immune to these issues but are a bit more forgiving.
There are other issues such as efflorescence (whitish cloudy effect resulting from wetting the floor and bringing soluble minerals and salts out of the installation). This can take a few days to materialize, if indeed it is going to at all so to seal too soon can cause problems.
So, you must still aim for as dry a floor as possible but you may not have to wait anything like 10 days. First of all, there are things you can do to minimize the amount of water left to dry out. For example, borrowing/hiring a wet vac during the deep clean will remove much of the water (this is also the most effective way to clean and rinse anyway). Then you can take measures to accelerate the drying out of the floor afterwards, open windows and doors, place a large fan to move the air through the room, even hire a space heater. In this way you may get back to a substantially dry floor within 2 days. You can hire a moisture metre to check it, if it is in the green zone then it would certainly be OK for modern water based systems (less than 10% moisture content)
Removing the deeper set oil stains may not be as easy, you may need a poultice for that – and that process itself can take 24 to 48 hours. Any tiles where you intensely spot treat with a poultice may be even more wet than the surrounding one, but a decorator’s heat-gun, or even careful use of a hair dryer can quickly dry out one or two tiles.
Can you walk on them when they are drying? – Sure, as long as your feet/shoes are clean and dry there will be no problem, the vicious circle happens when you clean, then whilst waiting to dry, you walk dirt back into the floor – so take care to be clean whilst it is drying and no problem, just a quick brush or sweep before sealing will be fine. Maybe you have a couple of spots to clean, well a quick wipe with a damp cloth should be OK and that will dry out in minutes.
So, in your situation now I would first do a thorough deep clean, (not got room to go into that here, but I have posted about this before) using say, Heavy Duty Tile and Grout Cleaner.
Then start the drying process off, however you can, and attend to any remaining spot stains with the poultice (follow instructions on the tub). Check the poultie 24 hours later and repeat if necessary – in the mean time the rest of the floor should now be dry.
When you are ready to seal I would suggest that you use something like Seal & Finish Low Sheen – it is much easier to maintain than oil and wax, as detailed in the article and also the article from March has a video showing exactly the steps to take.
Regarding slip resistance – this is a whole other issue. There is no easy answer to this except to say there are a lot of myths – floors are most slippery when they are wet, and or contaminated with slippery liquids like oil and grease. The unsealed terracotta is about as slip resistant as it can be – as long as it is clean and dry. Adding a coating sealer like seal & finish low sheen will actually not affect the dry slip resistance of the floor (in fact in some instances it temporarily improves it) but when it is wet it is a different matter as any coating will keep the water or grease at the surface so it is bound to have an effect, reducing the slip resistance of the floor (again, you are slipping on the water, not the sealer but the sealer has stopped the water from soaking into the tile). However the amount of difference it makes is not huge and may still be more than acceptable – the key is good house keeping and keeping the floor clean and dry. A waxed floor would be worse, so too can any other hard floor surface.
Hope this helps
Ian
Ian Taylor | Aug 2, 2010 | Reply
Hi Frank,
I’m afraid that as I am based in the UK, I have no idea what the quality of porcelain is like at the store you mention. My advice would be to go and ask them for a sample of the one you like and let the contractor see it. Maybe do some testing, see if there is a wax coating that is hard to remove, try a marker pen to see if it leaves a stain etc – do this before making your buying decision.
Hope that helps
Ian
Phil | Aug 30, 2010 | Reply
Hi
I have heard that you can add beeswax to the linseed oil whilst boiling. Is this correct? If so, what mix propostions would you recommend?
Ian Taylor | Aug 31, 2010 | Reply
Hi,
I have not heard that one! So I cannot tell you what proportions – The thing is, terracotta has been around for so long now, centuries really, so of course there are many many different variations on how to treat it, different Tilers have developed their own methods over the years.
I would have to ask what benefit there is in adding wax to the oil? Also, most of the Tilers in the UK would buy ready – prepared Boiled Linseed Oil – I do not know of anyone here who would ‘boil their own’ – but I could be wrong. The most popular way seems to be; pre-seal with Boiled Linseed (usually several coats) then after grouting and drying, finish off with beeswax, (or some paste wax) sometimes thinned with a spirit.
Ian
Pat Carey | Aug 31, 2010 | Reply
Hi Ian,
Have read your blog with interest and as you seem to be very knowledgeable on the subject of terra cotta tiles we hope that you can help.
In June of this year we had a large room tiled with 40 cm sq. terra cotta tiles in a house in south west France. The tiler laid the tiles with adhesive rather than mortar. As a result he advised that he could clean the floor with a diluted acid mixture within one week and that we could oil the floor one week later.
This we did and put on 4 coats of a linseed oil and turpentine mix. After the 3rd coat marks began to develop which were very clearly sponge marks from the cleaning solution and foot prints of the workmen who laid/cleaned the tiles.
The supplier of the tiles says that the cleaning should not have been done for several weeks after laying to allow an efflorescence of salts to come out of the tiles but also says that the tiles can be cleaned using a machine. They have now been left for 2 months since the 4th coat of oil and the markings remain quite clear. I am concerned that the brush and foot marks are now imprinted in the tiles by the 4 coats of oil/turps.
Can you advise if you think it is at all possible that the tiles can be cleaned back to their original state?
We would really appreciate your advice on this as it looks as if it may be a very costly mistake.
Pat
Ian Taylor | Sep 1, 2010 | Reply
Hi Pat,
Sorry to hear about this; OK, I would agree that using adhesive in place of mortar would speed up the process as there is far less water involved in the installation, so drying and curing times would be faster. It would also hopefully be slightly less prone to efflorescence. I think I would have left it perhaps a little longer than a week before using a cement remover/acid cleaner – 10 days say to give the cement in the grout enough time to fully cure.
If efflorescence had come out then you would have seen it as a greyish white couldy or powdery secretion – you may still get some yet. However It does not sound like the problem here.
Given you can see the foot prints and sponge marks after some coats of oil, it suggests to me that the cleaning of the cement residue was in sufficient. Where there is still some film of cement residue, the foot prints for example, then the oil will not penetrate the tiles so you will see the tile around the print taking-on more colour with each application while the ‘print’ area will remain unchanged – so the print or sponge mark acts like a stencil in negative – hope that made sense.
If I am right then this could be good news – in that in theory at least, if we can move the remaining cement, then that ought to allow more oil in and although you may not get 100% even colour – you should be able to get a bit more oil in to even it up a bit and reduce the impact of the stains.
Try some more of your acidic cleaner – just on the marks – I suggest you try to use a cleaner based on phosphoric, not hydrochloric acid. Try a splash neat on the worst footprint if you get no fizzing, then either the oil is covering and protecting the cement, or it is not cement. You may need to use a stripper – a solvent like turpentine or acetone to remove the oil you have put over the stain (I doubt you would be able to remove all the oil you have put into the tile, but where the marks are, the oil will, in theory at least, be on top of the cement residue, so you ought to be able to take that of to expose the cement).
Then follow the instructions on your cement remover and try to remove as much as possible. If you are successful you should be able to get some more oil into the tile to even out the colour.
If this does not work then I am not sure what else you could try – hope this helps
Ian
Pat Carey | Sep 1, 2010 | Reply
Hi Ian,
Thank you for your prompt reply – it is extremely kind of you to take the time to give us your advice/suggestions.
I think you are probably correct about the stencil effect with regard to the sponge marks. It appears as if either the cement residue was not properly cleaned off or possibly the product used for cleaning was not properly rinsed off and is now resisting the oil. (After another consultation this morning with the tiler we now know he did not use acid but some ‘special’ terra cotta cleaner which he bought in a tile shop.) However the reverse seems to be the case with the foot prints. They were there before the cleaning and seem to have absorbed more of the oil than the surrounding surfaces.
We will try the phosphoric acid and/or stripper suggestion.
Thank you again, we really do appreciate your help and we now feel more knowledgeable in discussing it with the tiler.
Pat.
julia | Sep 2, 2010 | Reply
Hi there,
can you advise us on the best way to restore our terracotta kitchen floor? It was originally sealed with linseed oil and regularly waxed with a very effective product that we bought from a specialist shop some fourteen years ago (sadly, now out of business—can’t remember what the product was called, alas). This served us well for many years, but since we ran out of this particular product, we have been polishing the tiles with beeswax — albeit not as regularly as we used to — but as a result the floor is now showing oils stains and is manifestly vulnerable to accidental splashes of kitchen cleaner at the hands of out somewhat slapdash cleaners! Apart from getting more efficient cleaners, what would you suggest we do to get the lustre and patina back on our floor (i.e. having thoroughly removed the dirt and wax from the floor, do we have to start from scratch with a linseed oil seal? Is beeswax the only polish you would recommend?) Basically, how do we deal with the unsightly oil stains and bleach spots?
Much obliged,
Julia Coster-Longman
Ian Taylor | Sep 3, 2010 | Reply
Hi Julia,
The first thing to say is that whilst oil and wax finishes on terracotta have some benefits – they have a ‘warmth’ that is hard to recreate with synthetic finishes. One of their problems has always been that, no matter how good the maintenance, or the care and love lavished upon them, sooner or later the wax builds up, starts to get a bit sticky attracts dirt etc, or the initially enthusiastic care and maintenance wains and the wax is allowed to diminish and the floor becomes more vulnerable to staining. Either way the floors reach a point where they have to be stripped back. Splashing bleach and other strong cleaners on the floor will also remove the wax in those areas – so tell the cleaners to open their bottles somewhere else.
However, usually it is only the wax that we are stripping, it is impractical to try to get the oil out. So typically the wax is stripped with either high alkali cleaners or solvent based strippers (depending on the condition and thickness of the wax), in doing so one would hope and expect to remove much if not all of any staining that had got through. The bleach marks should also go as they are really areas where the wax has already been stripped. When rinsed and thoroughly dry (drying may take some days) the wax is reapplied, several coats, and then buffed to the required finish.
I would try stripping with something like Heavy Duty Tile and Grout Cleaner, (at say 1:2 with water) as it does sound as though the wax has been allowed to diminish. If on the other hand the wax is thick, hardened and tough, you would need a stripper like Sealer & Coating Remover – this is a different process (there is a video elsewhere in the blog). Hiring a rotary machine with brush head along with a separate wet-vac would be a great help in this. Once the floor has been well rinsed and allowed to dry out you can reapply your wax. There may be other alternatives to the brand of beeswax you are using, or you could consider going to a synthetic coating – most of these are removable with alkaline cleaners so if you did not like the look you could go back to waxing quite easily.
Hope this helps
Ian
julia | Sep 6, 2010 | Reply
Hi Ian,
thank you so much for your extremely helpful advice. The floor is already looking tons better and will henceforward receive the TLC that it has been crying out for.
Much obliged,
Julia