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paint thinner poof
Sunday, April 6 2008
Taking advantage of the warm weather, today I was out in the shop making a set of eight steel clips out of blank 3/4 X 3/32 inch mild steel bar stock. Each clip started as a six inch long blank that I bent in three places to form a little hook that could attach to the bottom of my large handmade solar panel, rising up from below and curling around the bottom end of a pane of glass, thereby keeping it from sliding off the panel's frame (otherwise the only thing holding it would be silicone caulk). The clips looked something like this:
The trick with making something like this is to develop a good technique when bending the first one and then copy that technique slavishly. The time necessary to make the last seven in total should be about the same as the time necessary to make the first one.
Later I was up on the roof doing some more prep work on the panel prior to the installation of the glass and I thought, what the hell, I ought to pressurize it and make sure there were really no leaks. It hadn't had any when last I checked, but once I had it up to 75 PSI, air came pouring forth from a visible 5 mm crack in that one junction that has been plaguing the panel since October.
At this point it was clear that I'd never be able to tell if I'd fixed the joint after soldering it; evidently flux will plug up a leak for a short period after soldering, leading to a false sense of security. So I developed a new technique for looking for leaks. Using a container of paint thinner and a paint brush, I'd thoroughly paint over the suspect solder joint after repairing and re-pressurizing it. The thinner, though acting from the outside, will quickly dissolve any flux plugs it encounters in the joint, thereby exposing the leaks either as visibly-bubbling phenomena or (in one case tonight) a faint ticking sound heard only when my ear was held an inch from the joint. It seemed there was still enough moisture in the long-drained panel to cause my soldering to fail. Only by reorienting the panel several times and making sure air could flow freely from one end of its plumbing to the other was I able to make what seemed to be a leak-proof joint (at least for now).
When I was done for the evening, I decided to dispose of the container of paint thinner by simply throwing it into the woodstove (this is how I typically dispose of inflammable chemicals). At the time there was no actual fire in the woodstove, although there were some glowing coals. When these failed to ignite the paint thinner, I decided to light the fumes with a lighter. Big mistake! POOF! It wasn't a loud explosion, but it did create a shock wave strong enough to scatter ashes a dozen feet from the stove. The resulting fireball, though brief, was bright enough to catch Gretchen's attention from the teevee room upstairs. "Are you okay? she asked. Nothing bad had happened, though, aside from the fact that most of the hair on my right forearm had been painlessly singed off. The house now also had the fragrance of diesel fumes, which Gretchen was concerned about the animals breathing. It was a little too cold to throw open all the doors and windows, but we were going out to dinner anyway, and to at least spare their lungs, we also brought the dogs with us.
Dinner was a social call at the Garden Café in Woodstock with Jenny and Doug. Jenny is the woman with the artificial leg who runs a farm animal sanctuary in Willow (beyond Woodstock and Lake Hill). Well over a year ago, bad energy had developed between Jenny and Kathy (the director of the Catskill Animal Sanctuary) and this had driven Gretchen and Jenny apart. But since October, when Gretchen had a massive falling out with Kathy, there's been no reason for Jenny and Gretchen not to be friends, particularly if the friendship didn't involve animal sanctuary business. So there we were knocking back the wine and eating delicious vegan food. Last time Gretchen had socialized with Jenny, Gretchen hadn't even been a vegan. Now I was the only non-vegan at our table.
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