It's interesting man, I'm seeing a small resurgence in interest for solvent teks around here. For a long time, everyone went over to rosin lol.
There are a number of factors we need to take into account when purging.
First of all, which solvent is being used? This is crucial information to determine what pressure/temp will be required.
Secondly are you measuring the pressure in the chamber? It is crucial to use a gauge to ensure that you are creating the right relative pressure in the chamber. Vac purging is not as simple as connecting a vacuum pump to a chamber and just turning it on for a while and waiting til the material looks done. This could easily lead to serious over purging or could the slowest, longest purge you've ever tried.
Ideal purge temp is a variable that changes with the relative pressure in the chamber. There is no 'right' purge temp, only the right temp for a given solvent at a given chamber pressure. In fact, solvents can be cold boiled using no heat at all given the right chamber pressure!
With some more info on the solvent being used, whether there is a pressure gauge on hand and what kind of heat setup is needed, I can help more specifically
That pic up top definitely still has plenty of residual solvent leftover. Also the errl is not at all evenly spread in a thin film which will lead to very uneven purge - once you have fully purged all of that oil, some sections (the smaller, thinner deposits) will be way overpurged.
I do not purge on parchment at all, ever. I do not recommend the use of any kind of parchment/silicone in a vac chamber. Remember that the wrong chamber pressure/temp combination is gonna lead to offgassing of such substances. If you are not measuring temp and pressure in the chamber, you are really taking your chances on this one! I suggest using nothing but borosilicate dishes for purging solvent out of a solution.
Proper purpose-made lab glass dishes are best, since these will be perfectly flat, allowing for the thinnest, most even possible distribution of your solution across the surface for faster, more even purge.