heres a link
I mention draino to remove anodising.
You will need to remove anodising in order to polish.
Try polishing first with silvo if your rag doesnt start going black your parts are probably anodised theres not much point sanding ano by hand either it’s pretty hard
I believe the ‘anodize remover’ is caustic soda, but I’m prepared to stand corrected. My granny used to pour it down drains because she thought Draino was a bit posh.
I also use mag wheel cleaner to get caked-on grime and tarnish off old alu parts…works a treat.
If you want a satin rather than shiny finish or to buff out fine scratches before a final polish “essteele stainless steel and copper cookware cleaner” is the DG.
While we’re broadly on the topic, automotive gasket remover will take off powdercoat.
na some guy was giving a tutorial. I remember now… he had a list of equipment including all i said about plus a bottle of beer for the part while he waited. Was an old stem, came out looking really shiny. I thought i had saved the link but no dice. Someone on here must know, since they did post it annnnyyone?
i went out and bought the oven cleaner today, as well as an new old seat post.
The “active ingredient” is sodium hydroxide (NaOH). I mention draino as i have used it successfully in the past, also (and more importantly, though other methods may do the same) it results in green bubbles for propper mad scientist moments. If you try draino make sure to check the tin there is a wussy version out there which has little or no NaOH in it
Can you ruin the aluminium if left with caustic soda on it for too long?
I’m thinking about doing this to a set of hubs.
If I left the hub shells covered in caustic soda overnight is there a chance of wrecking threads or melting the shell?
…maybe I should read the guys tutorial also…
Yes,
You’ll end up with pitting corrosion on the aluminium, ruining the surface finish. The NaOH destroys the passivation that you usually get with aluminium exposed to water (tight AL2O3 layer, same concept as the Cr oxide on stainless steel) by dissolving the oxide layer. Then the Al is dissolved by the NaOH + H2O, leaving sodium ions and an aluminate in solution.
For extreme ‘stuck alloy stem in steel fork removal’ you can leave it in NaOH + H2O and dissolve it entirely, leaving the fork behind.
Not sure on the time to pitting, if you can’t find out, use a sacrificial component first. Or just leave it for long enough to strip the anodising.
That’s the thing I don’t understand- once you have polished a component, how do you maintain the polish? I would have thought the aluminium would quickly oxidose again leaving a dull finish. Am I missing something?
It does, but if you have a better base (~1-5um surface roughness) following your sand/polish it will still look better than when you started, and will be easier to touch up.
Or you can clear coat over it.
Or plate a noble metal (eg Rh/Pt/Au) onto it. :roll: