Gilders Compo is a handmade mouldable substance using a traditional recipe. For use on mirrors and picture frames. This can be pressed into moulds, hand modelled or carved when hard. Compo firstly needs to be heated to use. It will last about a month in the fridge or up to 6 months in the freezer. It can go mouldy but this can be washed off in warm water and is still ok to use.