No double boiler needed. It can be done at room temp with a fan blowing over the surface area of your evap dish. I do recommend adding some heat near the end of the purge, as the alcohol evaporates, the oil will form a skin or matrix at the surface, adding heat will loosen the matrix by increasing viscosity, ultimately allowing the residual alcohol escape. 1) Minimal contact time regarding the ISO wash (QWISO = Quick Wash) I used to make this quite often.. I count out loud 30 seconds maximum contact time on your first wash, this includes pouring time. 2) Be extremely gentle again at first, just use a very light swirling motion for the first wash. Then like the Dry Ice Method, increasing in shaking and contact time in small increments. 3) use a series of filters, starting from bigger holes to finer holes, then the coffee filters. **you do not want to have any material in the coffee filter as it's draining ** 4) Dab the coffee filter(s) with fresh alcohol beforehand, this will decrease the drainage time 5) Wash up to 3-4 times, keeping each wash separate.