On Feb 11, 18:49, Vintage Computer Festival wrote: thick fingers? The eraser Don't use contact cleaner. Proper contact cleaner contains oil. It's not nearly as bad as WD40, but you don't really want the board covered in a flm of oil. If it's just one board, try washing it in warm water with some washing-up liquid (dishwashing detergent). If the grime is that stubborn, assist the process with a dishwashing brush. Rinse well, dry carefully (shake off or blow off as much water as possible, use some IPA to help remove the water). If you're in an area with very hard water, the final rinse before the IPA might best be done with distilled or deionised water. Don't dry the boards flat, the object is to let as much water (and any minerals dissolved in it) as possible to drain off. Make sure the board is thoroughly dry, which may take a day or two, especially if there are switches or sockets on it, before you try to use it. If that's too much like hard work, or you have a lot of boards to clean, consider using the dishwasher. That's what's used commercially (at least, for small-scale stuff). However, DON'T let it do the drying cycle (too hot for some things) and don't use the dishwasher if the board contains anything that might suffer: transformers, relays (unless hermetically sealed), paper labels that must be preserved, anything with extremely fine wires (core mats), etc. I've been told some very old ICs (grey type) don't like being immersed in hot water. I've never had a problem with that, but YMMV. Some old types of compressed paper boards (Paxolin) may not like the dishwasher either. Same rules apply about drying. -- Pete Peter Turnbull Network Manager University of York