Sealing bathroom grout is the only way you’re going to avoid mold and mildew growing underneath your bathroom tiles, and ultimately damaging both your wall and your tiling work. It will help to extend the life of the grout you’ve applied, and sealing it is actually a very quick process – it should only take you around 15 minutes to complete.
However, almost all grout manufacturers recommend that you wait at least 3 days, if not longer, before sealing the grout so that it has enough time to set. Then, to avoid breakdown of the grout as the sealer wears off over time, the sealer should be reapplied every several years.
Sealing Bathroom Grout: Using a Penetrating Sealer
Penetrating sealers, although they may feel like a bit of a hit to your wallet, are worth the extra few dollars in the long run. These sealers actually soak into the grout’s microscopic pores, reducing the grout’s ability to absorb foreign compounds that could potentially stain the grout surface.
A penetrating sealer is able to do this because it is typically composed of latex or silicone solids which are suspended in a base of water or mineral spirits. After application, the base evaporates and thus leaves the solid latex or silicone inside of the grout.
Ensure that you choose a high-quality penetrating sealer, especially for use inside the bathroom. It should be noted that penetrating sealers that are non-pigmented will not produce a gloss on the surface of your grout, but it can darken the natural color of the grout you’ve applied.
However, after all penetrating sealer dries, it should cause the grout to appear normal until it comes in contact with water – after which the water will bead on the grout, making the grout area appear almost waxy.
Sealing Bathroom Grout: Using a Membrane Forming Sealer
Membrane forming sealers are designed primarily to resist water, though they are often manufactured for the purpose of changing the original color of the bathroom grout. They tend to then be used as grout colorants, since they have these added pigments.
In areas like the bathroom where there is a lot of moisture, using a membrane forming sealer will not prevent water from seeping underneath the tiles or grout – and with a membrane sealer overtop the grout, there is no way for the water to evaporate and let the grout dry out again.
This extended exposure to moisture, of course, is what causes mold, mildew, and wall rot. In addition, membrane forming sealers should not be used with glazed tiles, as they will only adhere to unglazed surfaces, forming a glossy membrane on the surface of the grout.
When it comes to bathrooms, it is very rare to not use glazed tiles, since they’re much easier to clean. Thus, best to avoid membrane forming sealers when sealing grout in the bathroom – save it for use on floors only
When You’re Ready to Seal
There are a few rules to adhere to when it finally comes time to seal your bathroom grout. First, read the manufacturer’s instructions very carefully – each product will often have very different instructions, and making assumptions about how to use the sealer will likely just end up in more work for you, whether it means re-grouting or even re-tiling your bathroom walls.
Secondly, if you do get sealer on your bathroom tiles, wipe it off before it dries. Excess penetrating sealer, if allowed to dry on tiles, will form a haze on your tiles that is nearly impossible to get rid of. Sealer also dries very quickly, so have a rag on hand to remove any spots immediately.