I’m trying to make a 4"X4"X6" block of machinable wax but seem to be coming up with something a lot more viscous than what others must be making because it is always full of air bubbles. Can anyone tell me what I’m doing wrong? I’m using paraffin wax from the art store and high density polyethylene (HDPE) shopping bags. After stirring for about an hour until all the plastic dissolves, I pour it into a wooden mold and place it into a preheated 300F oven for a half hour and then let it cool there overnight (is preheating the mold critically important?). Once I tried straining it, but it was too thick and the strainer clogged. Usually it seems to skin and harden instantly when not in the bulk of the liquid (for example, wax that splashed on the wall of the pot that I make it in hardens). Here are the ratios that I tried:

5:1 wax to HDPE heated to 300F -> about as thick as dough
7:1 heated to 275F -> thick as batter
10:1 heated to 275F -> thick as honey

Instructions that I found online all seem to use a 4:1 ratio with LDPE… Thanks for any advice,
John