IOD paper clay is an air dry medium, and one of our favorites. Like most paper pulp based air dry clays, some shrinking, warping, and cracking is inherent. We like these qualities for a distressed, authentically vintage look.
Our favorite way to apply moulded pieces is to remove them from the mould while still moist, and adhere to the surface with the appropriate glue so it conforms well. For vertical surfaces, use a piece of low tack tape to hold it in place so it doesn’t slide.