I watched the latest video and the way I remove all the residual foam is with a grinder using I non-twisted stainless steel wire cup brush. It's a full sized DeWalt grinder. Takes it right off without damaging the skin.

https://www.homedepot.com/p/WALTER-S...D314/305936661

https://www.homedepot.com/p/DEWALT-1...8_vzjk#overlay