The vacuum distillation of MDP2P must, of course, be done in a vacuum atmosphere or the ketone will polymerize at a certain temperature. The temperature/vacuum correlation is not something that is easy to calculate. In the real world, the numbers are often very different even from the figures given by the JAVA applet pressure/temp calculator at rhodium.ws. In swim's observation, most bees use vacuum pumps like the "yellowjacket" that theoretically pump down to one micron or less and use pump oil and a cold trap, while some use water aspirators or recirculating water aspirators with pumps, etc. Swim has often looked in his different catalogs at the many pumps offered, and one that is very appealing to him is the diaphragm vacuum pump. For example, KNF and Vacuubrand are the most noted. Swim likes these pumps because they are easy to clean, don't require pump oil, can take a good amount of oil or water vapors without breaking, and are small and lightweight. He has one that pulls 120 mmHg (that's what the catalog from the place he got it from says anyway) which he uses for vacuum filtration. There is a small shop a few miles from swim's house that sells surplus or used scientific equipment, and they have a KNF pump that theoretically pulls 10 mmHg for $500, as well as more expensive ones ($1000+) that are rated for 6 mmHg and 1.5 mmHg. swim was wondering if anyone had used these types of pumps to distill ketone, if they are a good choice, and if the 10mmHg one is good enough for the job. The reason he asks is that it seems that vacuum pumps don't pull even close the amount they say they do. There was a post by LabTop explaining why a long time ago. Swim has been using metabisulfite as his way of purifying ketone, and the best color he can get this way is a yellow/light red color. he would like to get purer ketone in the future. Anyways, thanks for any comments.