I have attempted to cast a model using Easy Composites' Fast Cast Polyurethane Casting Resin. The cast failed as the resin did not fully cure. Half the model cured but the rest came out like thick honey, see image above. I'm not sure why this happened, but my immediate problem is, how do I clean the uncured resin goo from my mold? The mold is made of RTV silicone.

It's very rare that fast cast won't cure at all unless the mixing ratio is well out.

What looks like has happened here is that your quite thick moulding has absorbed some of the heat used to exotherm the cure hence its not cured.

I would apply some heat in an oven for a few hours to force a cure.  If it still doesnt cure then something has gone seriously wrong with the resin. 

Acetone would be the best method to clean off the liquid goo if you cant get it to cure.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant