So I've made some mistakes in my past and I'd like to rectify them.

No, I'm not talking about that "strip club incident" I mean I have models I thought looked dandy, but now I'm a better painter. I think I used GW varnish and/or kryon matte clearcoat.

Anyone know if there is something good for this like simple green is for paint? I'm afraid to try and then have a half-ruined model.