I am building an acoustic guitar and have reached the point where I have to "finish" the guitar.  It has a walnut back and sides which I need to fill before applying a  french polish finish.  The walnut has an open grain and there are several suggested approaches to filling it.  West One 105/206 epoxy resin is popular.  But I'm rather taken with glasscast 3 for its self levelling and clarity properties.  It would be applied with a squeegee (old credit card) very thinly and then flattened with increasingly fine abrasive to achieve perfect flatness before applying shellac.  So my questions are:-
1.  Is it suitable for use as a grain filler in the way that I've described?
2.  Is it Ok to sand?
3.  What might be the drying time for a very thin coating?
4.  Are there other considerations that I should bear in mind?
Thanks in advance.
Bikergordy
Arthurian Guitars

Yes you can use the GlassCast 3 in that way.  Typically it is used in a reasonably thick layer and allowed to self level but a thinner layer is possible.   

You can easily sand and flat after fully curing to get the flat finish prior to overcoating.  You could polish the GlassCast and keep the natural GlassCast finish - many have done similar.

You are looking for 24 hours to cure before sanding.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant