Due to the quick curing nature of the PX60, it could be anywhere from 30 minutes onwards.  You want to catch it when the resin is just firmed up but still tacky and the fresh layer of resin will bond and cross link with it fine.  You will need to keep an eye on it as the exact time will vary considerably depending on volume of cast, ambient temperature etc.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

hi, I'm going to be making a mould box, and filling it, around the original model,  with Xencast PX60 Medium Flexible Polyurethane Resin.
My question is: how long after pouring a 1/2" deep, initial layer, can I place the model on top and fill the mould box, please?

Thank you.