My guess would be when you went back and de-greased to re-tan them you didn't add salt and they acid swelled? This will give you skin, especially the thin edges, that will be stiff and brittle, they will crack when you bend them. If this is the case they are not salvageable now. To say a skin that was not properly de-greased before tanning is ruined and can not be salvaged is 100% incorrect, we've done it time and again, attempted home tans and also from people that are starting to tan for others but are still learning on greasy skins. Same goes for African skins that were "tanned" in Africa. To re-tan a syntan it is tougher to wash the tan out, but every syntan formula I've ever seen uses such a low percentage it won't completely tan the skin, plus the directions typically create a surface tan. Don't expect the EZ 100 to create a truly washable skin, even the chrome tans that are backed up with the syntans as the finish tan, whish is what they are formulated for, are not truly washable but they will handle moisture better than mineral tans. If you need to de-grease multiple times you either need a better de-greaser or better instructions, note: badly grease burned skins are an exception.