I went through this on Modernvespa and I never found definitive answers, if you have, would you mind sharing? I've read quite a few DIY threads wher it has been done. Does it reach anealing temperatures?
Thanks,
TD
There are a lot of studies done on the subject of powder coating hardened aluminum, and altering the hardness of such. Even in commercial or industrial operations, the loss can be as much as 5-10%. Often tests are done only on single gauge aluminum and don't include welds or hydroforming. Annealing aluminum takes place between 300-410°C (depending on alloy), and cooled at a controlled 20°C per hour to 290°C. Powder coating requires temperatures in excess of 200°C.
I used the phrase 'approaching annealing temperatures', due to the discussion being for DIY. The temperatures in the 200's are the danger zone. DIY powder coating is often done with little or no real controls or testing. There's also the added danger of the DIY oven not being properly preheated, for the proper amount of time. Controls of the process and testing of the finished product are all important. Most DIY'ers powder coating aluminum won't have a Rockwell hardness tester, so then the testing becomes the use of the bike. How much hardness loss is acceptable? Even with best practices, hardness will be lost. I'm not sure any loss is acceptable for a more durable finish on a bicycle. To me (for me) it would be better and safer to get the bicycle with a proper finish from the factory, or use a quality paint that doesn't require baking. There are some amazing acrylic polyurethanes used in automobile and other industries, that come close to and in some ways exceed powder coating.
