I want to use Ultra Proflex SP in combination with rock and glass - but as a sculptural medium, too, meaning there will be quite a bit of the adhesive showing. I experimented today, having added 1:1 water:latex, and it smoothes very well, and polishes up nicely, too - now what I want to know is, will this be weather proof and reasonably strong on its own at all and if not will sealing it afterwards be enough?

The adhesive will be frost resistant.. and will probs darken with weathering.. sealing will also probs darken it and you will have to be careful what you seal it with as it needs to be suitable for exterior use...

Darkening is just fine, sounds good in fact, what sealer would be best do you think? Got the lithofin stone sealer, would that do?

Yep..

A little trial piece... not sealed yet... just finished it tonight... Flower Rock Nov 10 003.jpg