On Thu, 2004-11-18 at 10:26 -0500, james wrote: Brilliant! That is extremely useful general-purpose information. I also happen to have what in Norwegian is called isopropanol, I can only assume that they are the same? Again, thank you, that info will come in handy. I have some insanely dirty SGI KB's I got recently, too. -- Tore S Bekkedal <toresbe(a)ifi.uio.no>

Quick update on my keyboard washing experiment: Background: I dumped red wine on a cheapo ps-2 keyboard I got from dell. It's all plastic but I like the "feel". I mopped up the wine but the keyboard would not work the next day - some keys worked, some did not, some produced odd results, some where "sticky". What I did: I read the email on using the dishwasher so I tossed it in the top rack, upside down and added a little liquid soap. I washed it on a normal cycle with no drying heat. Afterward I shook it dry and then put a hair dryer to it for about 10 minutes. I left it on it's side with a towel underneath for a day. After day I then plugged it in and it didn't work. bummer. So, I opened it up. Lots of water still inside. And, a nice thin plastic flexible pc board with lots of black contacts (carbon?). Each key had a little round rubber "dome" with a black spot (carbon?) in the middle. When a key is pressed the key presses the rubber dome and the black spot contacts the flexible pcb and makes contact. I removed and dried the flexible pcb (it still had some minor wine stains which I washed off with water. I left the whole thing open to dry for a few hours. Then I put it back together and it works like a champ! Yea! So, the dishwasher worked well and cleaned out all the crud (and most of the wine) but opening it up seemed to be the correct thing as a final step. The water inside may well have evaporated if I chased it with iso alcohol and left it in the sun but it's cold here now and I didn't do that step. Also, I think the "two layer" construction of this really required opening it up to get it to completely dry. ymmv :-) -brad

Same thing. I think I mis-spelled it anyways. What we are talking about is isopropyl alcohol. I think isopropanol is supposed to contain a little water. If it contains water, get some that has as little water as possible, like 90% alcohol.

No, not quite. Now, I haven't doine this with electronics myself. But I think I understand the issues to an extent. Thing is, you don't want to just let the water dry on the device. You can do that if you are using _very_ pure water and have rinsed the device _thoroughly_, because then the water will just evaporate and that's it. But if you're using tap water, it contains dissolved salts and suchlike. (Even soft tap water does - just in lower quantity, and to some extent different salts.) And if you just air-dry electronics, these salts get left behind in a layer on the surface. _Sometimes_ this causes no trouble, but if the salts happen to be conductive enough (for values of "enough" that depend on factors beyond the scope of this discussion), or in some cases if they're insulative enough (for example if they're being deposited on bare conductor pads used by a switch), they will interfere. So you want to eliminate the water. This can be done mechanically, but it is quite difficult to get rid of enough of the water mechanically in most cases. So instead, you do a rinse with a compound that (a) is itself highly volatile, (b) does not come with dissolved salts and such the way tap water does, and (c) is miscible with water and thus will remove the water that's left on the surface. In the chemistry lab, when washing glassware, we used acetone for this (maybe they still do - I don't know). I wouldn't want to use acetone on electronics, because too many of the plastics and other compounds used in electronics are too soluble in acetone. But isopropanol also satisfies the conditions I sketched (though slightly less well) and is a far less effective solvent for things like chip housings and PC board resin. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B