Hudson308 

Some of you may remember the Trek 930 frameset and parts that I managed to snag for a song off of eBay a few months back. I suspect the reasons nobody bid against me on this are 1) the seller had a big fat “goose egg” for a feedback score, 2) there was a sizable shipping charge listed, and 3) it was obvious from the description that the frame had a badly stuck seat post. The seller also missed a huge opportunity by not disclosing that it was a rare Columbus-tubed model 930. I did manage to spot the remnants of a Columbus decal in the poor auction photos, but we all know that stickers can be applied to anything. Because the seller was local and the opening auction price was low, I decided to take a chance on it.


When I finally managed to get it home, I confirmed that it does indeed have a dove-stamped steerer. I also confirmed that it had a VERY stuck seat post. What’s worse, the post was inserted a good 6 or 8 inches into the frame, making the “hacksaw blade method” of removal very difficult. It’s obvious that a previous owner had tried hard to remove it, even going so far as to drill the post laterally so that a rod or screwdriver could be used to twist it. I’m grateful they didn’t destroy the frame in the process. Here’s how I was able to persuade it to come out. After stripping it down to the bare frame, I clamped it upside-down in the stand for easy access to the bottom bracket shell. I then cleaned all traces of grease from the bottom of the inside of the seat tube. Then using a urethane rubber cap and some RTV cement, I carefully plugged the bottom of the seat tube. Once the RTV had cured for a day, I propped the frame upright in a long, rectangular plastic planter box that had no drainage holes in the bottom. This allowed me to capture any spillage, and also allowed me to monitor if my plug was leaking.

This is the product I used, available at Ace Hardware stores. As with any strong chemicals, it’s critical that you use the proper rubber gloves and goggles whenever working with this stuff. It WILL burn a hole in your skin, and the fumes should not be inhaled. Also be sure to dispose of any waste in an environmentally responsible manner. I ended up using about 3/4 of this 1lb. jug.


Every day for a week when I came home from work, I would carefully fill the seat tube with cool water. Then using a small funnel, I poured 4 heaping teaspoons of the lye crystals into the seat tube. I didn’t bother trying to mix anything externally, because the churning, spitting acid mixture in the tube seemed to mixing itself just fine. After letting the acid soak in the seat tube for 3-5 hours, I dumped the frame out and rinsed the seat tube a number of times with clear water. Then I would repeat the process the next day.


After eight of these applications, I carefully rinsed and wiped the frame down and clamped it upright in the work stand. A couple of firm twists with a pair of channel-lock pliers coaxed the remnants of the seat post out. What’s left to do now is to remove the plug I installed in the bottom of the seat tube, and then I’ll lightly run an automotive brake cylinder hone down the tube to remove any remaining aluminum residue.

Campagnerdo 

Nice work!

P.S. Lye is sodium hydroxide, it's a strong base, not acid.

Hudson308 

Ah yes... thanks for reminding me of that!

Giacomo 1 

I admire your persistence! I learn things on this forum everyday.

I'm guessing this Trek is pretty special, so give us pics as you build her up.

fleslider 

Nice work! gotta love picking up the "impossible" fix and fixig it!

bobwysiwyg

So, what, if anything, did it do to tube? Just curious.

AdventureManCO 

When I saw that pic of the post disintegrated at the bottom, my first thought was, 'oh no...did it eat through the seat tube???

bwilli88 

The lye just attacks the aluminum not the steel. the inside of the seat tube just needs a bit of honing to clean up any residual aluminum.

clubman 

Consumers can't even buy pure caustic soda where I live anymore. I get nervous looking at a bare hand holding a container. FWIW, from 1973 to 76, I worked summers at a chemical tank farm filling 45 gallon drums of this stuff from railroad tank cars. We wore gloves and a visor, no respirator. I can't believe I'm still alive. Bad ass.

clasher

I've done this to a few bikes before, it's quite messy but worth it on a good frame.

bobwysiwyg

Good to know. In keeping with my Sig line, had to verify. Hope you don't mind.

bwilli88 

from some dude on Quora
Overall reaction-
2 Al + 2 NaOH → 2 NaAlO2 + H2↑
First you should think why Al would react with a base?..The reason is simple Al is a amphoteric metal which makes it capable to react with both acidic and basic species.Now coming to reaction,Under normal circumstances, aluminum does not react with water, as an impermeable protective layer composed of aluminum hydroxide either forms within seconds or is already in place. With the addition of sodium hydroxide, the formation of a protective layer is prevented. With the production of aluminates (Al(OH)4-), the amphoteric (capable of acting as either an acid or a base) aluminum hydroxide Al(OH)3 goes in solution:
2 Al + 6 H2O ---> 2 Al(OH)3 + 3 H2
Al(OH)3 + NaOH ---> Na+ + [(Al(OH)4-)]
The aluminum completely dissolves.

Hudson308 

Yeah... what he said.

SJX426 

I did this once too, or close to it. Two things worth mentioning. One is that the reaction is exothermic, it gets really hot, it will not burn the paint off but the solution will remove paint. Second is that it's biproduct of the reaction is hydrogen, which is extremely flammable, don't allow sparks near the gas given off.
My post was nearly 12 inches in the frame, forcing the lye approach. Here is what was left when I was finished.

WP_20160107_001, on Flickr

Tin foil thin. This is what I started with

P1030267, on Flickr

My efforts took a couple of hours. I did not rinse between applications, just emptied the seat tube of the what was left. I premixed the solution, about 100 ml.

noglider 

Well done.

Our bathtub had a slow draining problem for a couple of years, and I used Drano (lye) periodically. Once I spilled some extra in the bathtub, and the fumes gave my eyes a burning feeling, so I ran out and put a fan in the bathroom. I try to be extra cautious handling hazardous stuff, but accidents still happen. As far as I know, I was not injured.

degan

Wish I had done this with the only frame I've tried to get a seatpost out of using more than brute force and penetrating oils. I used hacksaw blades and a sawzall to cut strips out of the post. I started carefully but got super complacent because it was taking forever and sawed a hole through the frame like an idiot. I laid out a book on the workbench and just went on autopilot with the sawing. It was a lower end Univega that someone else had already given up on, but I still felt like a complete idiot when I looked down and saw the tip of the blade starting to poke though the seattube.

cdmurphy

Just a few points of caution: 1) Lye or sodium hydroxide or NaOH (different names for the same stuff) is very dangerous if it gets on your bare skin, and extremely dangerous if it gets in your eyes. It can destroy your corneas or cause permanent blindness - no joke. Don't even think about using it without proper eye protection (facemask, or full goggles. Glasses aren't really enough protection.)

2) Strong bases like lye will strip most paints (maybe not catalyzed urethanes like Imron). Ive often used oven cleaner to strip paint on steel parts. I would be very careful using this method on a frame with paint that you cared about.

Mista Sparkle

As someone currently sing NaOH to dissolve some aluminum off a superconducting cable, I gotta say this does the trick =]

FBOATSB

Stepped in a puddle of sodium hydroxide leaking out of a tank at a chemical plant in the late '70s. It destroyed the boot leather and burned a small part of my foot to the bone.

Hudson308 

Thanks, CDM; I don't think these points can be stressed too much. I debated even posting this info due to safety concerns, but with the proper care it's an effective way to remove those seat posts (and stems) that simply won't budge using other methods. In the end I opted to chance it, hoping that with the proper respect this method can be used to save a good frame. I also concluded that having vague information available on how to do this was as much of a hazard for people.

RandolphCarter

I used this method a few years ago on my 1986 Trek Elance 310

Before I resorted to lye, I tried all the other tricks to loosen up a stuck seatpost.

I soaked it in ammonia for a week, it didn't loosen up.

I tried thermal cycling - alternating passes with a heat g-u-n and an ice bath, it didn't loosen up.

I tried soaking it in PB Blaster for a week, it didn't loosen up.

I tried clamping on an old stem and fork, to use as a lever. It didn't loosen up, and I stopped before I bent or broke my frame.

I cut the top of it off, and took a hacksaw blade and cut a slit vertically down the length of the post from the inside. It didn't loosen up.


Keep in mind these were all ways of loosening up posts that had worked for me in the past.


I cut 6 more slits vertically down the length of the post, it didn't loosen up.

I snapped the top of the post off attempting to fold the slivers of the post in on themselves. It was still stuck.


post with slits cut in it, and not able to make it break loose from the seat tube:



I figured I should google for other ideas before taking the frame to a machine shop to try to have it drilled out.

I found on youtube.

(cue sounds of harps playing, and the clouds parting to allow a shaft of sun to gently bathe my frame in mellow golden light)


So I plugged up the bottom of the seat tube with silicone caulking - above where it meets the bottom bracket. I let the silicone cure for a week.


I bought a container of 100% lye crystals from Lowe's, it was $12.

I used layers of gloves, safety goggles, and long sleeve shirts.

Do NOT fool around with lye, it will happily turn your skin, muscle, and fat into soap, leaving a nice crater where your exposed body parts used to be. I have a nice shiny crescent-moon shaped 2" long patch near my elbow where I discovered this for myself. I didn't feel a thing while it happened.


I used an old plastic measuring cup and put 500ml lukewarm water in it, then 4 capfuls of lye crystals.

DO NOT use hot water for this.

SLOWLY and CAREFULLY and GENTLY pour the crystals into the lid, and then GENTLY pour them into the water. GENTLY stir the crystals after each pour - you do not want to mix a larger volume of the crystals with water.

SLOWLY and CAREFULLY and GENTLY pour the lye solution into the seatpost. It will start bubbling away like one of those 'mudpot' geysers in Yellowstone. Let it sit for a few hours.

Carefully dump the sludge out and test if you can remove the post. If you can, rinse everything THOROUGHLY and congratulate yourself. Otherwise, prepare another batch of solution and repeat the process.

Mine took multiple baths over 4 days.

Remnants of post after an invigorating lye spa treatment:



Like others mentioned, lye will damage most paints/powder coats. During my efforts, the lye solution bubbled over where the seat stays join the seat tube, and also down the back of the seat tube. This caused my paint to either get discolored / scorched looking, or be peeled away. The paint on my frame already had lots of, um, 'character', so I didn't feel too guilty about damaging it more by slopping the lye solution all over everything. The frame got a thorough rinse and scrubbing, and then I lightly sanded the worst areas and gave them a few layers of Rustoleum clearcoat.

noglider 

Excellent description, @RandolphCarter, and the video is scary enough to confirm that I will never attempt this.

jpc2001

How dangerous it he NaAlO2 this produces?

Is it OK to send it down the sewer, or is this like copper salts where it's bad for wildlife (and people)?

ljsense

It looks like this aluminium salt is used in water treatment, and I don't see a bunch of environmental warnings about it -- one chemical fact sheet said it's dangerous to breathe, and will cause irritation.

When I've done it, I put out newspaper or other coverings and disposed of it in the trash instead of the water supply. The other thing you create is hydrogen, which of course just floats away past your cigarette without causing any issues.

jpc2001

This suggests there's no harm: Sciencemadness Discussion Board - Sodium aluminate aq. solution disposal? - Powered by XMB 1.9.11

I read something else that suggested you could react it with acid to precipitate out solid aluminum, and get the PH of the remaining liquid back to neutral. Toss the solid in the trash, and the liquid (now with very little metal in it) down the drain. But it sounds like that's unnecessary.