Classic Rendezvous list friends,
I agree with Scott that one needs to show respect when dealing with NaOH. But just a little fear would be realistic. I am an eye surgeon, and I have seen too many horrendous injuries from accidental exposure and deliberate violence with lye (which is what sodium hydroxide is). It is a BLINDING injury. ALWAYS wear total face protection with a polycarbonate shield. Put it on before you take the container from the locked cabinet where you keep it safe from children and dumb adults, and don't take the face protection off until it is back there and the rest is rinsed away. If you can't do this, take your component to a professional metal shop. Shiny components are not worth your vision.
Ed Feinberg Newton, MA (AKA Edward Feinberg, MD, MPH, Professor of Ophthalmology, Boston University School of Medicine)
Message: 1 Date: Mon, 18 May 2009 12:18:02 -0700 From: Scott Minneman <minneman@onomy.com> Subject: Re: [CR] Anodize no! Schadenfreud yes! To: 'Tom Sanders' <tesanders@comcast.net>, <Classicrendezvous@bikelist.org> Message-ID: <04e101c9d7ed$5d6cc440$18464cc0$@com> Content-Type: text/plain; charset="us-ascii"
I strongly suspect that Sodium Hydroxide is Sodium Hydroxide...that's the active ingredient, whatever brand is on the label. It's potentially nasty, but what do you expect, given what you're asking it to do?
Yes, the Easy-Off is gooey -- it has a thickening agent that helps it cling to surfaces (like...ovens). This can be really good if you've got a bike part that's too large to submerge, or one that has a steel bit pressed in somewhere that can't deal with the liquid-based process.
I've stripped anodizing with Easy-Off and I've used the Eastwood (or maybe Caswell) stuff. I've never been patient enough to experience the discoloration problem, but I suspect it's actually an issue with the particular alloy. If there's much copper or magnesium in the aluminum alloy, it'll make the surface blackened and ugly (look up how to "de-smut" the parts to fix this issue without too much elbow grease (it's a quick acid bath (again, potentially nasty stuff))). Does anyone have a different explanation (other than smut) for this blackening issue that some report?
Yes, be careful, but don't panic...these are chemicals that require respect, but don't warrant fear. It's not a chemical reaction that's going to run away from you. It doesn't produce lots of hydrogen gas, so you shouldn't blow up your kitchen or garage.
You know yourself. If you're up to doing this, you know it. If your memories of working with chemicals are littered with images of flames, eyewash stations, and men in yellow suits, then maybe this isn't the kind of project you should attempt.
Scott Minneman
San Francisco, CA USA