P.38 FILLER has over 30% more resin than other fillers, which gives it much greater adhesion. This makes it the recommended choice for applying over POR-15.
P.38 has ultra fine particles for perfect feathering of edges, and is manufactured under vacuum, which eliminates those pesky air holes you’ve experienced with other fillers. It’s more flexible, tougher, and able to tolerate higher temperatures than other fillers (you can even use it in a baking oven!).