Tile/Grout sealant?

[andyjs]

Several years ago I made a small tile patio pond as a 4-H project, but I never found something to adequately seal the grout. As far as the interior is concerned, it just leaks slightly in one corner. The exterior however was completely destroyed by weathering from water getting into the grout. I'd really like to try to salvage it and retile the outside, but I need something to keep water from getting into the grout and under the tiles. Here it is in its current sad shape:

Other than being dirty, the interior is fine, but as you can see by the rim, lots of the exterior tiles have fallen off

 

[kzimmerman]

put tape on each side of the grout joint, masking tape will do fine. Then, smear a thin layer of aquarium silicone onto it, make sure you press it firmly into the grout. use an old credit card to squegee the excess silicone off, and remove the tape, allow to cure and you should be good to go. I caution people against the stuff you can get at a hardware store, as it is generally not 100% silicone, and can leach some nasty stuff into the water.

 

[andyjs]

I had considered silicone, but I don't know how well that would work on the actual mosaic design. There are a lot of seams there to cover. And I think the aquarium silicone is a waste of money. You can get 100% silicone at the hardware store much cheaper. You just have to know what you're looking for

 

[apisto]

Use the stuff they use for waterproofing walls, or epoxy or gel coat