What causes scum/soap coagulation?

Method 1: Sometimes dried soap suds will build up over time. Your filters need to be cleaned and rinsed with hot water as often as you can to prevent the build-up of gunk. Some soaps are more prone to this happening than others, and there is some debate about which ones are best. Many tinters believe baby shampoo is the worst for dried soap suds. Newer shampoos contain parabolins, which is basically just wax. These compounds can build up very quickly and make your slip solution look like jelly if you don’t clean your filters enough.