We've been running the same heat exchanger on our soft plastic injection machine for a few years. We recently pulled it to refurbish (clean, replace heaters and thermocouples, re-run wiring etc.) and found there there was a lot of brown/black burnt (baked on) residue inside the heat exchanger. (Probably plastisol, but it could be from colorants or glitter.)
It's pretty hard, I don't want to ream it out (I want to keep the plastisol channels smooth), so I was hoping someone here had some experience on how to soften the burnt plastisol so we can remove with a non-abrasive brush.
Have you had a similar problem? How did you fix it?