I forgot to say that I want to use this as a birdbath. That is why I want to seal it before hand.

Hey! I am working on a terracotta saucer myself!!! I had this saucer and someone broke it so I used gorilla glue to glue it back together and am using drywall tape and a coat of mortar on it...gonna coat the whole thing like that and hopefuly it will be okay...hope someone chimes in to say ya or nay with this idea...I like your idea of using it for a birdbath, I think either way, silicone or thinset would work, mine is just gonna be a plain jane saucer when I am done...hopefully it fits the planter I want it to, sheesh better go check that out!lol!

Seal the saucer before you mosaic it, preferably with a penetrating sealer like tile lab- all surfaces. water can soak thru the other side in terra cotta. silicone or thinset will work just fine. Make sure you bring it in for winter because terra cotta can crack in the freezing weather no matter how well sealed. and let us see pics when you are done, we are junkies!

Wackyweeder is right - you can't leave it out in freezing weather.

Use a penetrating sealer, then use thinset mortar to both stick and grout the tiles. I use this for outdoor large-scale projects, and trust me, when completed the tiles are going nowhere. I use stained galss for the tiles with these materials with success.

I would caution using Gorilla glue - I use it myself, but on such a project it will expand and move the tiles.

I use a concrete/brick sealer all around. Terra cotta is a moisture absorber and I've found it's the only thing that blocks moisture completely. Moisture will lift tiles regardless what adhesive is used. I use silicone for stained glass myself....

Here is a link that might be useful: moosaics.com

Here is my finished one....

Here is a link that might be useful: {{gwi:145598}}

I've made a couple mosaic mini-birdbaths by using grout sealer over the terra cota and then using silicone to combine the pieces and to stick stuff on. Then I grouted and sealed again. They've been sitting outside in my garden for at least two years and still look nice.

Thanks for all your help. Got the sealer. I would like to know what everyone uses to color thin set/mortar? Where is the best place to get the color?
Thanks for more help.

Lowes has a few bottles of liquid colorant. I used the terra cotta colorant on my front fountain. On a terra cotta pot I mosaiced several years ago, I used the same thing MOOSAICS suggested - Quikcrete's brand of concrete/masonry sealer. I lasted beautifully until this past winter when we had below freezing temps in NE TX, and most of the tess fell off. Safest thing to do is as WACKY and WULI suggested - BRING IT INSIDE FOR WINTER!!!

You can get colorant at Michaels, AC Moore and other craft supply stores, or at Lowes as was already said. I generally just use ordinary acrylic paint. You can use the tube kind, but the liquitex in the jars is easiest to use - pour a little in at a time, you can always addd more but can't remove it once it is in.

When using colorant, make sure you mix enough to grout the entire project - it is next to impossible to match the color from one batch to the next.

Regarding slowmedowns post and masonry sealer on terra cotta - just as wacky and wuli mentioned 'freezing weather' is very damaging to terra cotta. The adhesive used on your project combined with freezing is what caused your tiles to pop off. What adhesive did you use?

Here is a link that might be useful: moosaics

In thinking more about this question I realized that not only did my tiles fall off, the whole pot disintegrated, The tiles fell off in sheets because the outter layer of terra cotta fell off. I even had one pot fall apart that was just painted. I have two very large Mexican pots by my swing patio that are mosaiced and have weathered last winter just fine, and the one w/the most tiles I was so anxious to mo that I didn't even seal it. It has been planted for several years, and shows no sign of deterioration. So, I say to self, it's the quality of the pot that makes a big difference. On all outside projects I use cement-based adhesives. Still, I won't be mosaicing terra cotta for outside anymore.

I'm with Slow, I have done some wonderful terra cotta piggy banks, and they fell apart on me...I don't really care about the saucer I just did, even if it lasts for a season...it is under a roof system so it may be okay for now too.