base2 

Attempt number 10.
It can't be stuck if it's liquid

Iride01 

Sometimes I find myself wishing I could try out such things. However I've never had a stuck seat post or stuck quill in my steerer tube that a rap with a hammer wouldn't cure.

Oh woe is me!

Pretty frame color. What groupset is going back on it?

SoSmellyAir

I am curious as to (1) the material of the frame and the seatpost, and (2) how the composition that is liquifying the seatpost does not also damage the frame?

base2 

I have a bunch of left-over Ultegra 6800 stuff from various projects. I also have some Velo Orange 11 speed downtube shifters & a set of Shimano aero brake levers that haven't see a bike in a while....In short, I haven't really quite decided yet.

The whole project is contingent upon satisfactory results from the alignment table. This frame was dumped at our Co-Op so bent the wheel was binding in one chainstay, & the crank arm binding on the other. So this whole project really is just for the challenge & for the gamble.


The frame set is steel. Not sure what kind. Probably nothing impressive, but "good enough."
The seatpost was a Thompson that was evidently never greased before being put out to pasture where by the frame filled with water & subsequent freeze/thaw cycles pushed out all the chainstay shaping & tire clearance dimple.

Nothing is cracked. So I think some judicious use of some wooden blocks & clamps might return the chainstay to original form.

The bubbling cauldron-of-doom you see here, is powered by Potassium Hydroxide & tap water. My wife only makes soap as a hobby now. But, her business has been shut down for a few years. The Potassium Hydroxide was a mis-ship from a supplier that had been collecting dust in storage. So, I figured this was as good a' use as any.

(For general info: Potassium Hydroxide is usually used for liquid soap like dish or hands. Sodium Hydroxide is usually used for solid bar soap.)

Steel doesn't much react to strong bases in the way that Aluminum does. Just another way "steel is real."

SoSmellyAir

I see! I [probably] had a steel bike in my childhood, but that was before I learned any chemistry.

Mad Honk 

The caustic residue running down the seat tube and stays will eat the paint up, Kind of takes constant washing down of the frame to keep the paint from being destroyed. HTH, MH

base2 

Thompson seat posts are formed with the unnecessary material on either side removed.

Fortunately, the caustic soda/potash solution made quick work of the thinner areas. To get a nub to grab on to I cut the seat post down the seat stay slot & folded in either side of the cut. This allowed for easy removal by means of vice-grips attached to the tiny nub of overlap & light taps in the outward direction with a hammer.

SUCCESS!
Stuck seatpost success! by Richard Mozzarella, on Flickr

Grease your seat post.

CrimsonEclipse

Impressive.

Next time try a shaped charge

momoman

I just saw this on Instagram and had to share it. Use a hydraulic lifter/stacker to pull the stuck Seatpost out!

Hydraulic lifter

Or is that an electric lifter/stacker?

grumpus

I assumed from the title that you melted it out, rather than dissolving it. Dissolving appears to be much kinder to the paint. :-)