<span style="font-size:.0pt;font-family:Arial;mso-fareast-font-family:" times="" new="">There are several things that can cause stickups when making molds:</span><span style="font-size:12.0pt;font-family:Arial;mso-fareast-font-family:" times="" new="">
<span style="font-size: small; "><span style="font-family: Arial; ">There are several things that can cause plugs to stick in molds:

1) The surface of the plug is rough. This creates friction, binding and in the worst case a mechanical bond. Orange peel can make plugs with vertical surfaces (to the parting plane) difficult to remove even if the paint is very glossy. Not only should the surface of the plug be glossy but it should also be very flat/smooth.

2) The heat generated by the curing mold exceeds the operating temperature of the release system. If the temps of a curing mold exceed 125*F you can have problems with many waxes unless they are high temp waxes.

3) The geometry of the plug can causes it to get locked into the mold. Larger vertical (to the parting plane) surfaces can cause the plug to have to be extracted at very precise angles. The parts/plug coming out of the mold in the pictures below have to come straight out. The part cannot be tipped out in any fashion. I use two levers against blocks to slide the part straight out.

4) The surface of the plug is reactive with the resin. WAX IS UNABLE TO BLOCK REACTIVITY. You can put 1,000 coats on and still get a stickup if the surface is reactive. PVA, in combination with wax, will block reactivity IF THE COVERAGE IS ADEQUATE. If the PVA goes on too thin/sparse you can have issues. The PVA coat should completely cover the surface with one continuous film.

5) The release system softens the plug surfacing agent. Some waxes and release systems can soften some paints.

6) The paint on the plug is not allowed to adequately cure.

I typically use 4 to 6 applications of Part-all Paste #2 followed by PVA. On molds that will produce painted in the mold (PITM - see photo below) parts I use Frekote FMS sealer and Frekote 770-nc release to make the mold.<br style="mso-special-character:line-break" /></span></span><![if !supportLineBreakNewLine]><br style="mso-special-character:line-break" /><![endif]></span>