In the stone and tile industry, the term 'sealer' refers to a penetrating sealer which sits below the surface of the stone or tiles. Sealers that sit on top of the surface, creating a barrier, are referred to as 'coatings'. This article covers sealers: their benefits and limitations; when sealing is appropriate; and how to choose, use and maintain a sealer.
The left side of the sandstone is natural, and you can clearly see the water penetrating into the surface. The right side has been sealed with a penetrating sealer suitable for sandstone, and is keeping the water beading on top of the stone.
Sealers make stone and tiles easier to maintain
A high quality sealer will help prevent staining and moisture absorption, reduce mould growth and efflorescence, keep grout lines from discolouring, and make the surface easier to keep clean. It will last for between 5 and 15 years depending on the product, the surface, and its location.
Sealers are not water-proof or stain-proof
Sealers aren’t going to protect a surface from everything, all the time. Even the most expensive, highest-quality sealers will eventually allow staining if a contaminant is left sitting long enough. Quite simply, a sealer ‘buys time’ to clean up any messes before they cause staining; and if staining occurs, it is limited to the top few microns on the surface so it is much easier to remove without heavy restoration.
It is important to note that penetrating sealers cannot prevent acid damage on a calcium-based surface, as they sit below the surface, and the acid damage occurs on the top.
When to seal, and when not to seal?
Sealers come into their own on porous stone, or stone or tiles with an open pore structure. There is absolutely no need to seal a glazed ceramic, a matt porcelain, or many fine-grained granites – they are dense, impervious surfaces already. A sealer will not necessarily add any further protection. In these cases a coating could be considered.
Sealers are ideal for porous (or highly-absorbent) surfaces such as sandstone and limestone, marble and travertine. And grout – often the most-porous part of any tile installation – will always benefit from a well-applied sealer.
What to use and where
Using the wrong sealer – or using the right sealer in the wrong way – is not only ineffective; it’s also a waste of time and money. However by the time this becomes apparent (either by deep staining or visible sealer residue) the time and money has already been spent.
Choosing the right sealer is vital for a well-protected surface. There are many factors involved in choosing the right sealer. The better-performing sealers tend to suit specific stone types or protect against specific contaminants. There is little value in sealing sandstone with a sealer suited to granite as the active ingredient penetrates far too deeply, and similarly a sandstone sealer will not penetrate well enough into granite to be effective.
The carrier (water or solvent based) is important to get the active ingredient to the correct depth in the stone, and wetting agents are crucial to reduce the surface tension of the stone.
Appropriate sealers act quicker, perform their duty better and will often have a longer guarantee. With the research undertaken by well-known companies and their use of high quality ingredients it is little wonder that, although more expensive, they will save money in the long run. If you are unsure of the correct sealer to be used, consult a professional.
How to use a sealer correctly
Also key to a well-protected surface is the application method, which is equally important as the choice of sealer. It may seem straightforward to follow the instructions on a bottle of product, but in many cases if these instructions aren’t followed precisely the sealer’s effectiveness can be compromised, the product warranty can become void, or sealer residue can remain visible on the surface giving an uneven finish.
The right sealer for a surface, properly applied, will be invisible to the naked eye (unless you have specifically opted for a product that also enhances your surface).
Maintaining a sealer
It is possible to chemically damage a sealer, compromising all of the sealer’s protective properties. Once a penetrating sealer is applied, maintenance of the surface should be careful to also maintain the sealer. All sealers will have detailed maintenance instructions of how the surface should (and shouldn’t) be cleaned. By following these, maximum sealer life and protection levels can be ensured.
This article is the fifth in a 7-part series on dealing with stone and tile surfaces. It is based on the popular AusClean seminars presented by Garry Phillips of Slique International, Australasia’s stonecare experts. In our next article in the coming issue we cover coatings, including types of coatings that can be used, where they can be effectively applied, and correct maintenance.