Modern impregnating sealers have two key roles: firstly, for installation of the grout to ensure that any cementitious grout, residue or pigments can be removed fully from the face of the tile, and secondly, for the end user to be able to maintain the surface easily, whilst retaining the character, features and colour of the stone they chose.
Before the use of an impregnator on the entire floor, or even prior to laying, it is important to carry out a test on a small area or test tile. This will allow you to ensure that you are using the right product for the type of natural stone you are installing, and also to identify any changes to the stone’s appearance from the cleaning or sealing of the stone, so that these can be discussed and signed off before work is completed.
Precleaning: Especially important for heavy honed, tumbled, and textured stones, as these often come in with a layer of dust, which can mask the colour shades and features in the stone. Removing this contamination prior to sealing is important, to avoid it being collected in the first application of sealer/impregnator and causing marks within the stone.
Possible colour change: Testing one or two stones is important as products can change the appearance of the stone on application. This can be more apparent when using solvent based sealers as these can enhance the colour of stones more than some of the water-based alternatives.
Saturation/application time: Application of an impregnator is not just a simple wipe over the stone surface. For a professional installation, most stone will need to be saturated on the face to give it the best performance in terms of repellence and longevity.
Ensuring that all moisture is released: Prior to the first application on test tiles or the floor, ensure that the stone is fully dry and released of moisture. This can include moisture from the stones being wet in the packaging, surface finish manufacture, the installation process (adhesive moisture) or any pre-cleaning completed. Ensuring that all moisture is released will ensure the maximum protection from your sealer.
Removal of excess product after saturation: A surface that is left with a wet layer of product can sometimes sit on harder, more crystalline areas of the stone, and sink into the more porous areas, which can lead to a patchy or shiny finish. Buffing the stone after the saturation time will remove this excess and give a flatter, matt appearance, as it should be.
Work in sections: When sealing an area, work in small, controlled sections – apply the product as per the manufacture instruction and your results from the test stones.
And most importantly, maintain the stone and impregnator. Take guidance from your product manufacturer on the correct maintenance procedure and products.
By Bob Sewell, technical manager, Casdron
Technical manager, Casdron | casdron.co.uk
