I've given many an Iso sponge bath before, but this is the first time trying out the necroware-inspired (adopt respectful German accent) insert the hardware in the soapy water and give a gut (gentle) scrub. Thorough soap rinse out. A few hours in the warm sun, and now it is literally hanging by string on the washing line, getting a warm breeze in the face for a few more hours. We'll see how it looks after that. I was conscious to clear the board of any removeables first. There's one socketed IC which I'm considering removing in the interests of uber-thorough drying. Perhaps I'll leave that until after the day's natural drying process - as a test case, to see exactly how dry it got under there on it's own.