How long should I wait between applying coats of 521 epoxy resin?

There are two schools of thought for applying multiple layers of epoxy resin. Either apply additional coats while the prior one is still tacky (after about 4-10 hours); or wait 24 hours after full curing to apply. (Note – that after full curing – the surface will need to be lightly sanded to allow for adhesion of the next coat. Be sure to wipe away dust from sanding before application.)