Graham,
You just burst my joyous bubble when you asked if IPA was Isopropyl Alcohol. I was all set to tell my wife I needed to stock up big time on India Pale Ale.
For those stubborn stains I was gonna fill a kegerator with a nice Porter, and perhaps some Guiness in a second one for those really stubborn times! Oh the good times I would have had in the shop!!!
Sigh.
900x600 80watt EFR Tube laser from Liaocheng Ray Fine Tech LTD. Also a 900x600 2.5kw spindle CNC from Ray Fine. And my main tool, a well used and loved Jet 1642 Woodlathe with an outboard toolrest that helps me work from 36 inch diameters down to reallllllly tiny stuff.