Well, I have to go with penguintrax on the ,um, personal use cause I really don't know about the safety of that, but any acrylic
sealer** you use will be water-resistant (and acrylics would be best). Unless the baked polymer item is soaked continuously
, it should also be water-proof for all practical purposes.
Polymer clay is very water-resistant on its own though (it's plastic, remember), so unless you want to give the baked clay a glossy
finish, or you're going to put something on the clay which might be affected by water or air (like metallic leaf, or maybe watercolor pencils, etc.), you won't need
a sealer to make it wipe-offable.
can be a different thing though because some have petroleum-based solvents in their propellants, and those are what we try to avoid with polymer clay.
If you want to give your item a slight sheen or all the way up to a high gloss without using a liquid finish, you can use Kato Polyclay
brand of polymer clay (= sheen), or sand and buff (a little = sheen, or a lot with an electric buffer = high gloss).
I don't know what type of glaze works best with polymer clay, and which brands will be better at accepting it
Some finishes go on thinner or thicker, and some who buy Fimo glazes prefer the mineral-based one, but otherwise the type doesn't matter too mucy if it's an acrylic. All brands of polymer clay will accept most acrylic sealers well, with the exception of Kato Polyclay
accepting Varathane (since Kato has a very smooth finish, it tends to resist that particular type of liquid, so it would be best to go with Future if you use Kato and want to use a finish too).
For lots of info on types and brands of polymer-friendly finishes, check out this page ... and also look under the Sprays
subcategory if you really want to use a spray:http://www.glassattic.com/polymer/finishes.htm
(And here's a page that discusses the use of polymer clay in water and sun conditions, if you want to check that out too:http://www.glassattic.com/polymer/outdoor_snowglobes_fountains.htm
--- polymer clay "encyclopedia"http://www.glassattic.com/polymer/contents.htm