More to add to the knowledge base:
I have been experimeting more with HDPE and LDPE here is what I've found
I can heat a mixture of LDPE and HDPE in wax up to almost 580 F (severe caution is advised). When I do this its a small amount of wax (about 1/4 lbs) that I used for experimenting, I also keep the lid to the container near by (more on that below).
I have noticed that in mixing and trying to disolve the HDPE and LDPE in various batches that the paraffin steams quite a bit for a while then stops. It has come to my attention (and is confirmed after discussion with a polymer chemist friend of mine), that the parraffin is being refined as it "steams" what is actually happening is the low grade small molecule paraffins are vaporizing and turning into something that looks like steam. For any given paraffin there comes a point when I've boiled off all the low grade material. The result is quite interesting, a parafin that more closely resembles what I think migt be a smaller crystaline structure.
To further investigate this I decided to repeat the experiment with better controls, mainly pure paraffin. This time I used much less paraffin and attempted to boil it. Interestingly enough around 550 F the pure paraffin steamed like crazy, not long after that it suddenly burst into flames (this is where the lid comes in). I quickly placed the lid on the container and removed it from the heat source, it smoked like crazy and actually changed colors slightly (could have been some of the die that was left in the pan from previous experiments). SO... I have to repeat this experiment with an electric range, since my first experiments used only an electric range and later ones a propane camping stove. My theory is that the vapors of paraffin (which are flamable) found the open flame and caused the chain reaction. Use of a non combustion heat source will verify this. In any case it proves to me that refining the paraffin is a good step toward making a more usable wax. If I make larger batches I plan to basically make a still like would b used for alcohol, except I'm going to seal the mixing vat and purge it with argon welding gas to make sure no combustion is possible. I suspect the steam will be condensable into a low grade paraffin wax (no idea what i'll do with it).
Another idea I have is to mix in some soap to see if I can somehow lengthen the molecules of paraffin. A third idea is to mix in some activated charcoal to the mix,see if I can increase the length of the paraffin molecules (see the wikipedia entry on Paraffin).
I have also found through wikipedia that there are several types of waxes, including ultra low density Polyethylene, ultra low density polypropylene etc... I am trying to find a source of these, but I suspect that they will cost a lot, hence defeating the purpose of home made wax.
The interesting thing about LDPE is that it changes the way the wax molecules form, and that is the key to waxes. So I'm looking at a variety of household items to mix into the wax. Additionally I will look into bee's wax and see if it to vaporizes, I think using a strong base or acid can make or break the chains (have to confirm with a friend of mine). In any case its soon time to start better mix control, so I need to get a small scale of some sort. I also plan to try the rins on soda cans and water bottles (the PE plastic that holds them together seems proming). I'm thinking mix them with some paraffine and beeswax and see what I get.
One last thing add die last to your mixes since it can chemically break down at high temperatures.
of note the latest batches of refined PE and paraffin wax had some cooling issues. I allowed them to room cool but got the stuck in their mold, so I put them in the freezer which shrunk them and released them, but upon warming up to room temperature cracked them. It appears what happened is a difference in crystaline structure caused a thermal crack in them. So I'm trying to trace the problem down and find out why. In the mean time I've found real machinist wax at
http://www.machinablewax.com/ the price seems to be pretty good, under 100 lbs the price is about $4.00/lbs which isn't bad. I can't imagine making anything for less then about $2.50/lbs, and for the hassle I'm not sure if its worth it.
Does anyone have an experience using machining wax for lost wax casting patterns? I'vr seen there are various grades of waxes and was curious what the differences were.