-
Many thanks for the elaborate answer!
Seems a lot less straightforward and more dangerous then the interwebz "chuck it in chemical solution X, watch anodising bubble off, rinse, rub, rinse, result."
I'll resort to the plain old mechanical solution of elbow grease and wetndry so I will probably end up with more flesh (callus) then less (stumpy fingers) which is my preferred alternative.
Rodolfo-
I've removed the anodising from quite a few things over the years.
Most recently these cranks - https://www.lfgss.com/comments/15683861/I used caustic soda crystals. Start small with a teaspoonful in about 250ml of water, the reaction starts quite quickly. I used a small brush to daub it onto the cranks and let it sit for 30ish seconds, rinse it off and repeat until all the anodising is gone.
Experiment with different strength solutions, I've done it a good few times and feel comfortable using a stronger solution than above that has the anodising run off almost instantly. Obviously you don't want to dissolve any parts, so rinse frequently.Do it somewhere well ventilated, it gives off some pungent fumes. I usually do it in the kitchen by the open back door.
It's not that scary, just takes a bit of trial and error. If your cranks disappear then you know you've done it wrong.
TotalShanner
Since I have a local anodising shop, for whom stripping existing anodising before refinishing is a normal line of business, I've never even contemplated how to do it at home 🙂
Internet opinion is that it can be done with NaOH but that's not how pros do it because NaOH actually dissolves the metal better than it does the eloxiert coating. The professional method involves hexavalent chromium, which we've already been warned about once today, so you definitely don't want to try that at home.
Brief (30s-1min) immersion in a 10% (100g NaOH per litre) solution is suggested as a successful recipe. Bear in mind that this is a very caustic solution (pH>13) which will also strip flesh, so be careful. Keep a lot of plain water on hand to rinse both the cycle parts and any rapidly disappearing body parts.
I'd worry slightly about the steel/aluminium interface as it will be difficult to clean properly to stop the reaction. The GXP axle is only pressed into the driveside crank, so it's probably going to suck your caustic solution into the gaps by capillary action. If you do decide to proceed, think about how you're going to prevent that with some sort of compatible sealant, from both sides.