Because I heard some plastic types just release a bad gas and char...but I will be melting them with a heat gun if that makes any different...just blows hot air
Although all plastic is fundamentally the same, plastic is made by adding different chemicals together to come up with a compound of those chemicals. The use of the plastic would determine which receipt of chemicals to use to obtain the attributes you want for the finished product. Short answer, you'd have to know what was the intended use of the plastic you want to melt, to know if would be appropriate for your needs.
