This was off-topic for the Pax thread so I made you a new one.
I keep a small container of ISO that I use to soak screens and small pieces. I top it up if needed and when it gets pretty dark, I pour it through an unbleached coffee filter into a Pyrex dish to evaporate, and start over. After I've done this a few times the dish contains a nice but extremely sticky layer of what I call ISO-goo. This stuff isn't the tastiest but it isn't too bad, and it's highly potent. It's important to filter it if you do this. You also must be patient and wait until the ISO is completely gone, which takes several days.
Once your ISO has been used, it contains some dissolved resin. Anything you "clean" with it must be wiped immediately because ISO evaporates quickly and will leave behind some resin, although generally not enough to be a problem.