caustic soda/sodium hydroxide for alum. seat post
07-24-20, 02:34 PM
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caustic soda/sodium hydroxide for alum. seat post
I would like to know what would the best material to use to plug the bottom of seat tube, ( not the bottom bracket, but I show the bottom bracket anyway, its fairly small,) such that the caustic soda/ sodium hydroxide I pour into the top of the seat tube... such that it won't leak out. Rubber? cloth? something else? someone suggested old innertubes...
( I have cut off an aluminum seat post. but it is frozen and stuck in a steel frame. I have seen videos that say I can pour the caustic soda down the top of the seat tube and eventually it will dissolve the aluminum)
bottom bracket, seatube hole not visible obviously
( I have cut off an aluminum seat post. but it is frozen and stuck in a steel frame. I have seen videos that say I can pour the caustic soda down the top of the seat tube and eventually it will dissolve the aluminum)
bottom bracket, seatube hole not visible obviously
Last edited by jpjuggler; 07-24-20 at 07:35 PM. Reason: forgot to put in the question.
07-24-20, 07:35 PM
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ooops, yes. I forgot to pose the question.
I would like to know what would the best material to use to plug the bottom of seat tube, ( not the bottom bracket, but I show the bottom bracket anyway, its fairly small,) such that the caustic soda/ sodium hydroxide I pour into the top of the seat tube... such that it won't leak out. Rubber? cloth? something else? someone suggested old innertubes...
( I have cut off an aluminum seat post. but it is frozen and stuck in a steel frame. I have seen videos that say I can pour the caustic soda down the top of the seat tube and eventually it will dissolve the aluminum)
I would like to know what would the best material to use to plug the bottom of seat tube, ( not the bottom bracket, but I show the bottom bracket anyway, its fairly small,) such that the caustic soda/ sodium hydroxide I pour into the top of the seat tube... such that it won't leak out. Rubber? cloth? something else? someone suggested old innertubes...
( I have cut off an aluminum seat post. but it is frozen and stuck in a steel frame. I have seen videos that say I can pour the caustic soda down the top of the seat tube and eventually it will dissolve the aluminum)
07-24-20, 07:44 PM
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07-24-20, 07:48 PM
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...for what you plan on doing, you would be better off turning the frame upside down and plugging the end of the seat tube/post. You will require less caustic liquid, and the less of that stuff you use, the better off you will be. You pour the liquid into the seat tube through the open bottom bracket, which is now on top.
...for what you plan on doing, you would be better off turning the frame upside down and plugging the end of the seat tube/post. You will require less caustic liquid, and the less of that stuff you use, the better off you will be. You pour the liquid into the seat tube through the open bottom bracket, which is now on top.
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07-24-20, 07:57 PM
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Originally Posted by 3alarmer
.
...for what you plan on doing, you would be better off turning the frame upside down and plugging the end of the seat tube/post. You will require less caustic liquid, and the less of that stuff you use, the better off you will be. You pour the liquid into the seat tube through the open bottom bracket, which is now on top.
...for what you plan on doing, you would be better off turning the frame upside down and plugging the end of the seat tube/post. You will require less caustic liquid, and the less of that stuff you use, the better off you will be. You pour the liquid into the seat tube through the open bottom bracket, which is now on top.
07-24-20, 08:12 PM
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A rubber stopper would be ideal, and electrical tape around the tube-post openings, or seal them with paraffin. I would also suggest using gloves, chemical apron, goggles and a face shield when working with lye, as it will burn your eyes and skin and the reaction with aluminum will produce hydrogen gas which could cause bubbling and splashing. Nasty stuff, criminals throw it into people's faces causing blindness and disfiguration.
https://en.wikipedia.org/wiki/Acid_attack
https://en.wikipedia.org/wiki/Acid_attack
07-24-20, 08:20 PM
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Originally Posted by dsbrantjr
A rubber stopper would be ideal, and electrical tape around the tube-post openings, or seal them with paraffin. I would also suggest using gloves, chemical apron, goggles and a face shield when working with lye, as it will burn your eyes and skin and the reaction with aluminum will produce hydrogen gas which could cause bubbling and splashing. Nasty stuff, criminals throw it into people's faces causing blindness and disfiguration.
https://en.wikipedia.org/wiki/Acid_attack
https://en.wikipedia.org/wiki/Acid_attack
07-24-20, 08:37 PM
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It will dissolve your flesh to the bone. EXTREME Caution.
I recently freed (dissolved) a stem on an Ironman fork. The fork was placed upside down in a enameled steel pot.
Fortunately much less awkward than the seatpost.
The piece in the middle is almost completely dissolved.
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07-25-20, 07:22 AM
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I wrapped a piece of foam rubber in a thick plastic bag and shoved it up into the seat tube from the bottom bracket. I also used a huge drill bit to drill out most of the seat post.
07-25-20, 03:35 PM
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Originally Posted by bwilli88
I wrapped a piece of foam rubber in a thick plastic bag and shoved it up into the seat tube from the bottom bracket. I also used a huge drill bit to drill out most of the seat post.
07-25-20, 03:50 PM
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what size is the seat post ? I'd probably start smaller then work up to be 1/8" smaller than the post OD.
maybe 1" (25,4 mm)
maybe 1" (25,4 mm)
07-26-20, 03:13 AM
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Originally Posted by jpjuggler
wow, what size is that drill bit?
07-29-20, 01:08 PM
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I've decided to try the caustic soda/sodium hydroxide.
Question: does anyone know if after I pour it in and let it sit for some amount of time, if I should pour it out again before adding another dose?
Question: does anyone know if after I pour it in and let it sit for some amount of time, if I should pour it out again before adding another dose?
07-30-20, 12:47 AM
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I just add a bit more a couple of times, then pour it out and remove the sludge and reuse some of it if it is not too sludgy.
07-30-20, 04:06 AM
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Originally Posted by bwilli88
I just add a bit more a couple of times, then pour it out and remove the sludge and reuse some of it if it is not too sludgy.
07-30-20, 02:44 PM
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Victory. got it out. using caustic soda/. Thanks everybody for your info/help/suggestions.
for any others trying this, here's what I learned
-pour in a little at a time so that the caustic soda solution doesn't overflow thru the tubes. it at times would come out the seat tube, and or headtube and/or seatstays. The solution formua I used that I got from sheldon brown website was 100 grams of caustic soda to 250 grams of water. At first I was pouring the whole solution in at once, but then a LOT of it would just over flow and bubble back up or out. towards the end, i would pour 1/5 the solution in, wait 15 minutes and then repeat.
I ended up using almost all of the 1000grams of the caustic soda I bought. the seat tube was THICK. If I had started by being more patient and pouring in less at a time, I'm sure I could have used less.
-I did turn the bike upside down, and stuck a tube/funnel thru the bottom bracket.
-I used a cork to plug the open cut off seat post and used a bit of silicone to make a secure fit so the cork wouldn't come out.
-eventually I could pull out the seat post with vise grips.
for any others trying this, here's what I learned
-pour in a little at a time so that the caustic soda solution doesn't overflow thru the tubes. it at times would come out the seat tube, and or headtube and/or seatstays. The solution formua I used that I got from sheldon brown website was 100 grams of caustic soda to 250 grams of water. At first I was pouring the whole solution in at once, but then a LOT of it would just over flow and bubble back up or out. towards the end, i would pour 1/5 the solution in, wait 15 minutes and then repeat.
I ended up using almost all of the 1000grams of the caustic soda I bought. the seat tube was THICK. If I had started by being more patient and pouring in less at a time, I'm sure I could have used less.
-I did turn the bike upside down, and stuck a tube/funnel thru the bottom bracket.
-I used a cork to plug the open cut off seat post and used a bit of silicone to make a secure fit so the cork wouldn't come out.
-eventually I could pull out the seat post with vise grips.
