A very common misconception that sealers are waterproof. It is a claim that rears its head from time to time however recently it seems to have reached epidemic proportions and hence I think it is prudent to comment on this claim.
In a recent public forum I attended claims were made that the waterproof nature of premium sealers meant they prevented many of the problems either associated with water or caused by water such as efflorescence. The other assumption inextricably linked to this claim was it also made them stain proof.
The suffix that should never be used in conjunction with sealers is “proof”. No sealer manufactured in our industry provides a tile or stone with an impenetrable barrier. Sealers by nature are designed to allow vapour transmission and therefore at the very least will allow vapour to pass through them. This is a very necessary characteristic as all stone and porous tiles must be allowed to breathe in order to maintain their structural integrity that would otherwise be compromised by condensed or trapped water and the solids carried by the water. If a sealer allows vapour transmission then it also allows water to get into the tile and more importantly other contaminants that can be transported as a vapour.
The best and most common example of this is Efflorescence. I have heard from many sources how a good sealer will stop efflorescence. However this “good” sealer also has good vapour transmission, hence the two statements are contradictory and are at the centre of the false claims that are made. Efflorescence in most cases moves as a vapour and a sealer is designed NOT to stop or trap it. So Sealers will not STOP mineral contamination such as Efflorescence.
Sealers cannot in most cases cure to form an evenly gauged continuous film. This is particularly true of penetrating versions that penetrate inside a tile or stone’s irregular core. Coating sealers that are breathable (as they should be) are also not designed to form evenly gauged continuous films due to the chemistry required to bond to the great variety of surfaces – in both porosity and texture – found in especially natural stone. In other words the chemistry and sealing (both penetrating and coating) characteristics required to create a good sealer are quite different from those needed to create a good waterproof membrane. The bottom line therefore is that sealers are not waterproof or stain proof they will let things in at some point.
Then why use a sealer at all? I think most of us know the answer to this question already. If you have a stone or tile that is porous then some degree of staining occurs as soon as there is exposure to a contaminant. However if a sealer is applied it allows some time to react and to remove the offending contaminant. A poor sealer allows only a short reaction time to a small variety of contaminants where a premium one allows much longer reaction times to a much greater variety of staining materials. Simple really – insurance that works!
So getting back to the issue of water borne contaminants such as efflorescence, does all of this mean that applying a sealer that will NOT STOP efflorescence is a waste of time? Certainly not! In the case of efflorescence any mechanism that reduces the amount of water entering the tile or stone will reduce the amount of salt that evaporates. More importantly the evaporation will be a more controlled event with smaller amounts of salt coming out thus decreasing the likelihood of these accumulating on the surface where they can become very difficult to remove. Good sealers will achieve this by reducing porosity to very low levels.
Other water related issues such as freeze thaw and salt delamination are also eased by the installation of a good sealer. The mechanism is exactly the same as that described above for efflorescence. The sealer reduces the amount of water entering the system and therefore the amount of damage. However a sealer is only one part of a complete system that needs to be implemented to solve many of these water related problems. The notion that a sealer alone can stop efflorescence, render a stone or tile stain proof is just not fact. Using the example of efflorescence once more, the installation of a waterproof membrane, dense latex modified mortars and grouts, washed sand, quality cements, pre-packed adhesives, the correct falls and drainage and a good sealer all combine to reduce the risk of efflorescence. It seems to me that the marketing of sealers as waterproof and stain proof products is counter productive as it does not take long for clients to see that the sealer performance simply does not work at this level. In many cases this leads to a lack of confidence in sealer performance which in turn leads to sealers not being installed at all. However if the true nature and performance of sealers is expounded then and only then will clients understand the great value sealers can provide. Gaining reaction time to remove damaging contaminants and reducing the amount of water entering a tile and stone along with water borne contaminants are only two of the very valuable characteristics afforded by a good sealer. To conclude then, sealers are not waterproof nor are they stain proof.
However by affording a client reaction time they provide an invaluable service making tile and stone installations much easier to maintain which in turn extends the life of the installation.