On 4/25/2017 12:45 AM, ben via cctech wrote: Good point. Also with care, I've seen distilled water, then alcohol rinse (not rubbing, but pure of some sort), then air dry. This is used on optics to get rid of water spotting. The alcohol will flush out water that you could normally only wait out for evaporation, and rapidly evaporates itself w/o residue main problem are fumes and flames, so care must be taken when using it. thanks jim

On 25/04/2017 08:51, jim stephens via cctalk wrote: Not enough to do any harm if you dry it sensibly; besides, it's more likely to be choramines these days, not chlorine as such. I'd be more concerned about calcium and magnesium salts if you live in a particularly hard-water area, but, again, just dry it sensibly. I've done several backplanes with tap water, just blowing the excess water out with compressed air (but preferably from an oil-free compressor tank). I'd start with a vacuum cleaner assisted by a small paintbrush, then wash in water with a little mild detergent. Tap water if you live in a soft-water area, otherwise cheap distilled or deionised water, or from a dehumidifier. Finally, blow dry. "Little residue" would be more accurate, and some of that residue will be water (look up "azeotrope") - plus you need a lot of alcohol for something the size of a PDP-8 backplane. Blow dry, even after an alcohol rinse. -- Pete Pete Turnbull

On 25/04/2017 10:08, jim stephens via cctalk wrote: I should perhaps have mentioned that the idea is to flush the remaining water or alcohol out by blowing, not evaporate it like your hairdresser would :-) And you ought to use dry air, ideally - most compressors have water in their air. Except those spotty residues are usually hygroscopic, which can lead to corrosion later. Sure. Outside of electronics, my experience is in a chemistry lab needing clean dry glassware. The process would go something like this: - preliminary clean with whatever is best, often water and a little detergent/surfactant, then drain most off - rinse with distilled water - rinse with ethanol to flush out remaining water, then drain - rinse with acetone to remove the alcohol/water residue - air dry In photography, on the other hand, the final rinse would just be water - tap water if not too hard - with a tiny amount of a wetting agent (eg detergent) in it. For a backplane or some PCBs I'd compromise, but closer to the photographic example than the chem lab. In fact I've done that with my PDP-8s, rinsing the backplanes then blowing out most of the residue. Ouch! -- Pete Pete Turnbull

On 4/25/17 8:57 AM, Paul Koning via cctalk wrote: A water trap/oil filter is a trivial thing to add. Most come with a regulator which is handy. However, Generally the water and oil content is low to start with unless the compressor is seriously worn or your taking air form the bottom of the tank. Normally its good practice to drain the tank of water anyway. I've painted a few things in my day like racing cars. The alternate is a canister of nitrogen gas or cans of "air". The quantity needed is not all that great. Even after all that I'd still dry it with a little heat (oven at 180F or a clean empty container in the sun. I've used the dishwasher (sans caustic dish detergent) for cleaning then in the oven to dry for radios, computer boards, analog boards, and assemblies that can trap water. Things that turn or move like switches (open wafer for example) need to have contact treatment and bearing lubrication afterwards. Allison

On 25/04/2017 15:55, Tapley, Mark via cctalk wrote: Definitely. It takes a while, but even behind window glass (which is barely transparent to short wavelength UV) EPROMs can eventually lose their content. It happened to a friend who had a machine with no top cover, on a desk under a window, after about 5 years. But in direct sunlight, certainly just hours, and possibly just several tens of minutes if you're unlucky. -- Pete Pete Turnbull

That's what those stickers are for. Foil is probably pretty effective. Paper, not so much, because it's rather translucent. paul

On 4/25/17 6:06 AM, Pete Turnbull via cctech wrote: Considering your also trying to remove possible hazardous material and leave a noncontaminating surface its overkill to the max for a backplane. Again you are striving to neutralize the chemistry used. Considering a fan(s) has been blowing dust and who knows what else at it for years cleaning is good and any residue is nothing compared to the crud that was formerly there. In the pre-freon days the standard cleaner (when they did!) was a modified dish washer. The usual mod was reshape the racks to hold the boards and lower the heater temperature used for drying. A week rarely went by that someone had open it mid cycle to see if it was done. Plastics and elastic materials require more care for compatibility. Water is usually the safest but, none can remain. Allison