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