As part of our deep dive into sealing natural stone, we have been exploring why it is essential to protect your stone surfaces. In part 1 we looked at why stone should be sealed, how long the sealant will last and what you can do make sure your stone is always protected. Sealing natural stone is imperative and in part 2 we investigate some common issues that can occur.
Natural stone tiles for flooring will all have a different porosity. This is due to the very nature of the stone structure (see our blogs on sandstone, limestone and marble), but also on the final finish of the tile. Polished surfaces will be less porous than honed, which will be less porous than a tumbled or other textured finish.
The amount of sealant required will very for each different floor. The chemical make of each type and brand of sealant used will have an impact too. Underapplying or overapplying sealant can cause issues for the usability as well as final finish to a stone floor.
Underapplying sealant will not adequately protect the stone from spillages. If your stone has recently been laid and you are noticing that even water is leaving a mark (see blog 1 for a link to our YouTube video), then it is worth considering having a professional advise on further sealant application.
Overapplication of sealant can be similarly problematic. This is often seen as a residue or film on the floor that is difficult to remove and can itself attract dirt.
A high proportion of worktops have a polished finish, whether they are marble, limestone, granite or quartz. The process of polishing a stone tightens the surface tension of the stone. In the case of limestone and marble will change the chemical structure of the stone surface itself. This will drastically reduce the porosity.
One common issue that we see is the overapplication, or unnecessary application of sealant to a worktop which has very little porosity. If sealant is applied and the residue not completely removed, the surface can become tacky or greasy. Day-to-day use of the worktop can cause unsightly marks as this sealant residue encounters water, chemical and cooking spills. Often a high alkaline deep clean is required to remove this residue completely to rectify the problems.
Common issues with older sealants
Sealant technologies have moved a long way in the last decade. The formulation of high quality water-based and eco-friendly products have made application easier and the products more stable. Older sealants had a tendency to ‘yellow’ with age and especially when subject to UV light. Similar to timber floors, this is most noticeable to floors when furniture or rugs are moved. Often this process can be remedied with a high-alkaline cleaning treatment and/or resurfacing of the stone.
Sealants can be reapplied as a DIY process. However due to the issues stated above, this isn’t something we recommend for floors. There can also be issues created if topical sealants are reapplied without the floors having been deep cleaned first. Layers of dirt can be encapsulated in layers of wax or polymer giving the floor a permanently dirty or discoloured finish.
The instances where we do advocate re-sealing is for dark coloured stone. Particularly walls, worktops and sinks that are coming into contact with water on a regular basis. Shower walls, basins, sinktops and worktops made of darker coloured limestone and marble can fade over time with exposure to water and chemical cleaning agents. Reapplication of a colour enhancing impregnator can give these areas a bit of a lift and highlight the stunning natural beauty of the stone.
If in doubt, we always advise contacting a stone care professional. We are usually able to make an assessment on any problems that have occurred and advise as to how they can be rectified. You can read more about all of our stone restoration services here.
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