mrv 

I want to strip the black coating of an aluminum seat post. I am assuming the coating is anodized, but if I'm wrong, let me know that too.
I've found the post that says to use oven cleaner to strip anodizing: https://www.bikeforums.net/bicycle-me...odized-al.html

I have some "Aircraft Paint Stripper" (which, I am not kidding, the can says, "Do not use on aircraft"). I am not sure if the stripper is safe for aluminum (I'll check the can when I get home). Which could be why the can says don't use on aircraft (or some aircraft might be bonded alumimum...).

My question: After the coating is off the post, the post should oxidize like all bare aluminum does is air - do I have anything to be concerned about with my freshly stripped post in the steel seat tube? Like a permanent, irriversable bond between seatpost and seat tube?

The bike is an old Specialized RockHopper with the original post . The black has been rubbed off the post. It looks bad and I'd prefer to go non-black bits on my bike anyway.
Wouldn't be a problem if I wasn't breaking Rule #29.....

fietsbob

like all posts of aluminum in steel frames pulling it and keepingt a light grease layer between the 2 should be done regularly

say every other year.. you could of course buy another silver colored seat post.

anodizing is an electrolytic process, not paint. the color is a dye

rattle can the Black as a touch up to cover the scratches Or,

you can always apply tape over the parts that offend your refined Aesthetics

NB: There is reflective tape that looks Black during the day..

HillRider

Oven cleaner (aka sodium hydroxide, aka lye) will indeed remove anodizing but it will not stop there so, if you use it, don't leave it on long.

Yes, once the anodizing is gone, the bare aluminum will indeed oxidize but a coat of wax will slow that down. In any event, stripped or not, heavily grease the seatpost section that's inside the frame to prevent it from sticking. Greasing an aluminum seatpost is a universal requirement no matter what its finish but particularly importand for bare aluminum. Also, as a precaution, remove, clean and regrease the seatpost periodically, at least once a year or more often for a bike used in bad weather. That assures the post does not get corroded in place.

Wilfred Laurier

You should also know that the oxide layer on bare aluminum rubs off easily and leaves a grey mess on whatever touches it. The oxide layer immediately re-forms after being rubbed off, though, and the next thing that touches it gets the next coat of grey. Bare aluminum is almost as messy as greasy aluminum.

Booger1

Some oil,grease antiseize,will help you remove the post at a later date.

Polishing/waxing or both will slow down the oxidizing.

You can re-anodize with a plastic bucket,battery charger and Ritz dye if need be.

a77impala

Never mind!
Tried to delete.

HillRider

That's what started this thread to begin with. The post was originally black and the OP wanted to remove the black finish, not restore it.

mrv 

UPDATE
So I decided to do almost everything right:
THE STUFF:
1. bottle of lye
2. safety classes
3. plastic container
4. brush
5. gloves
6. shirt that can be stained without my wife complaining
7. aluminum seatpost i thought was anodized

Right, so you are probably smart enough to pick up on a key phrase in point 7, so THIS went no where.

There's mention in a linked post in the OP that says something like - "black is not anodized on aluminum, it's painted" - so that's pretty key.
Leading to THIS - Aircraft Stripper! yeah....

So after #3 steel wool, "fine" emery clothe (avoiding the max height stamp!), 400 wet sand, 600 wet sand - it's DONE!
another done
and one more done showing off my Brooks saddle I just got used for $60.

HillRider

OK, now a couple of more things: 1) does the post discolor over time and 2) does the post still clamp firmly in the seat tube and remain in place while you are riding?

mrv 

@HillRider - Excellent questions:
1) I don't know. Day 2 looks fine. I think you're looking for a longer time period.
2) In short, no. Even with a coat of NeverSieze.
In long, please see my addendum to my report below:
Test Conditions:
- location: suburb outside of Detroit
- temperature: cold, like 45F or something
- sunshine: nothing, nada, cloudy and crumby out
- rain: nope, or I'd stay home
- bike: 199? or 80? something Specialized Rock Hopper
- rider weight: 192lbs (give or take a couple of lbs)
- distance: about 7ish round trip (no cycle computer on the bike, as I don't really care how far I go as long as I can get there on time if someone is waiting)
Test Surfaces
- concrete slab
- side walk
- smooth pavement
- polka dots
- hop scotch block
- dirt
- leaves
- crushed gravel
- blind people dots
- and a bit of single track. It was too slippery to ride single handed and take photos.

Anything else to investigate?

Bat56

Number 2: No? As is, no it does not?

mrv 

My bad!
No slipping. The post didn't go no where... (relative to the frame). The clamp held the post firmly.

AND - for number 1 - discoloration - I was thinking of a machine shop class I took back in the 1990s. We made an aluminium meat tenderaizer -
milling machine work to make the head
lathe work to make the handle
threading, tapping, etc.
It's the same color as the day I made it - so I'm going to say this time next year the seat post will be the same color. If not, we'll dirt road ride to my favorite coffee shop and I'll buy.

531Aussie

I've done a few sets of cranks with oven cleaner.

After removing the cleaner, I polished hard with some Silvo or Brasso, then finished with Meguiar's All Metal Polysh (that's how they spell it ). I did some buffing with a drill buffer attachment, but I didn't notice any difference compared to elbow grease.

Some of the cranks turned out awesome, but a couple of older ones turned out crap, because they refused to lose their coating, even with a few applications of the oven cleaner.

I couldn't use sandpaper without putting in permanent scratches, even the super-fine stuff, so I stopped.

The dulling/oxidation isn't as bad as I predicted; I polish the cranks probably once a month.

This guy, Bruce Enns (forum member), did a great job on his quill stem with 1500 wet & dry and Simichrome polish.
https://www.bikeforums.net/attachment...p;d=1370181180