I use Tile Lab Penetrating Grout Sealer.

I use the same stuff and apply it with the little bottle with the brush tip I got at Home Depot.

I do have a question...how come the bottle applicator that comes full of sealer is cheaper than the empty bottle applicator?

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I bought some outdoor sealer from a tile store, it sure is smelly but my birdbath looks good!

I've used H&C concrete sealer on my terra cotta mosiacs that I keep outside. I put it over the glass and everything.

I don't seal outdoor things cuz I use the mortar for grout. Sealing grout, IMO, is to make the grout stain resistant - not to waterproof it.

slowmedown i thought on the post about grout or mortar that you used grout for out door projects and mortar was for adhessive.

Most of the mosiacs I've made are for outdoors. I've only been doing this for about 3 years, so I'm no expert - but I spend so much time on a project that I wouldn't dream of putting something outside without sealing it. My understanding is that the sealant not only makes the grout stain resistant, but a cement based grout is porous, so sealing it protects the grout from weather conditions as well. I'm in hot, humid Florida, so it's probably even more important here.

And if you do decide to use a sealer, be sure to let the grout cure for a couple of days before you seal it. And if your brand of grout says to "wet cure" it....be sure to do that...or the grout could crack.

The salesman at Home Depot told me grout sealer was only to keep it from staining and would still need to be done yearly for the one I looked at. When a brick mason bricks a house I've never known them to seal it but I'm a novice at this.

DEJA: I've used the cement-based mortar for adhesive and sanded grout on the first two things I mosaice OUTSIDE - the column in my front flowerbed, and the first project on the front walk. Since then, I've used the mortar for adhesive AND grout - w/no sealant. Like I've said - I'm still a student, so I'm not recommending ANYTHING - I'm just relating what I do and am happy with. I waited a year on the front walk project to see how it held up before putting down the second one. Come August, the second walk design w/have been a year, and w/be the second anniversary of the first one. Nothing has changed, even the column in back of my house that's on a wooden base, so I'll continue using the mortar for adhesive and grout on ALL outside mosaics, except when I use the concrete/wire mesh proceedure - and that's another story.

Hi slowmedown, when you say "cement-based mortar", do you mean "Thinset"?
Thanks in advance, I am still learning.
bianchi

Yes, thinset - some has latex admixture already added - some doesn't. I use the one w/it already in the mortar.

Thank you, I guess you also grout with it? or can if you so wish.
Bianchi

That's right, grout also.