Designing Kitchens and Bathrooms - How to seal and grout natural slate shower floor and walls?

A follow-up to a recent posting. Instead of tile, I put natural slate in a shower, for floor and walls. It looks great. However, given the metallic content of the slate, it oxidizes with water and produces an orange-like "rusty" stain in some of the adjacent grout (which is regular, not epoxy).

How can I avoid this problem? I am planning to re-grout the stained grout, let it cure, and then apply sealer to the slate and grout. But what kind of sealer will seal both slate and grout enough to avoid the rusty reaction? Short of applying spar urethane or lacquer, I guess (but am not sure) that regular slate or grout sealer only seal, but does not create a topcoat film.

Thanks

Maestro

Much of the so called slate sold today is shale and really not a great choice for any wet area. I know, I'm to late for this.:rolleyes:

Sealers will slow down water penetration, but will not stop it. If you regrout with regular grout, even the moisture from the grout is likely to produce rust in the grout from the slate. You may want to try spectralock epoxy grout. Its a bit of a bear to work with but will likely produce better results. Urethanes and lacquer will not work in an application like this so don't try it. Seal the slate before and after you use the spectralock.:)

The stuff I got from Home Depot (TileLab) says it seals both grout and natural stone. That said, I was not terribly impressed as it is not like it prevents stains at all.

Maestro

Much of the so called slate sold today is shale and really not a great choice for any wet area. I know, I'm to late for this.:rolleyes:

Sealers will slow down water penetration, but will not stop it. If you regrout with regular grout, even the moisture from the grout is likely to produce rust in the grout from the slate. You may want to try spectralock epoxy grout. Its a bit of a bear to work with but will likely produce better results. Urethanes and lacquer will not work in an application like this so don't try it. Seal the slate before and after you use the spectralock.:)


Is there any natural stone that works well in wet locations? When I get to my bathroom I would love to use natural stone but I fear that it will just be a nightmare to keep clean.

I guess (but am not sure) that regular slate or grout sealer only seal, but does not create a topcoat film.

Instead of guessing, test it. Grout sealer is pretty cheap as I recall.
If you have any scrap, seal it and glue it down to something that will hold some water. Submersse it in something that will accellerate the process. Optimally, I'd use a patina wash which is designed to rust metal. Instead of buying that.. cover it with salt water or some common acid to speed up possible rust/corrosion. For the sake of the test, lemon juice or vinegar would probably do it in a few days. I'd prefer some household vinegar so you don't wash away your corrosion when you rinse off your sticky lemon mess days later. :-)

Hmn.. even better. If you've got some old sealer.. something substantial like clear laquer.. coat half the scrap.. seal the other half and try to rust the whole piece. The laquered piece may not be suitable for a shower floor but it'd be a good control.

Thanks for the replies.

Is it a good alternative solution to apply something like Quikrete natural look waterproofer?

http://www.quikretecoatings.com/quikrete/naturalLookWaterproofer.jsp

This product is obviously used mainly for stuff like patios and sidewalks, and resists gasoline and salt in addition to water. But the can did not say it was for exterior use only -- the label even had a little generic sentence about interior use, without much detail. That said, I imagine that its primary use is not showers or interior wet areas. I would be concerned about chemical that are not meant to be near humans using a shower every day.

Thanks