Caustic Soda - no reaction

[stefanano57]

Just pop a couple of packets of Mentos down the tube and pour Coca Cola in. Fixed my piles, you'll have it out in no time.

 

[90's Ninja]

Well, this is my next step to remove a bottom bracket. Bolted the BB tool to the spindle and couldn't budge it even with a breaker bar. Broke the vice clamping the tool to it and torquing away... Took to the propane torch out of desperation and it softened the aluminum and stripped the splines. Called it a day and felt defeated but the lagers were ice cold and the sun was shining so not all was lost...now I gotta find me some caustic soda

I used 1 part soda to 3 parts water......that bubbled away nicely. Just burnt out an xtr m900 bottom bracket!

View attachment 748389

 

[JuanSock]

Stronger the better - but be careful it melts skin and generates a lot of heat. Very satisfying though. Oh, and it works best if you wear a white lab coat

 

[90's Ninja]

 

[BOBU]

OK, I'm BSc Chemistry and I've done it on a Marin Hawk Hill. I used KOH rather than NaOH as I have access to it but in principal exactly the same as it's the OH that does the work. From memory I used 10% solution and prior I'd tried WD40/GT40 and other lubricants so I found it didn't start to work as I expected. In total it took about ten applications to turn the seat post into tin-foil degraded mush. I suspect it took a while for the caustic to degrade the grease/oils before it properly got-going. I had a bung in the seat tube and applied via syringe into the bottle braze-on so I only got it in the seat post area, frame upside down and angled to protect as much of the rest of the frame as possible. Try to keep it off the paint as metallic paints have some Alu content I hear, rinse off with water if you get spillage. You must use safety glasses, I had caustic in an eye in 1979 and the pain was unimaginable and was lucky not to be blinded. On top of this, it generates A LOT of heat when it gets going properly, could have an effect on frame metallurgy...? I found that once the heat died down it was spent, I suspected anyway, so I dumped the contents and re-dosed. You need to be really careful with caustic, do the whole PPE thing as it is dangerous... best of luck & be careful.. ATB

 

[90's Ninja]

OK, I'm BSc Chemistry and I've done it on a Marin Hawk Hill. I used KOH rather than NaOH as I have access to it but in principal exactly the same as it's the OH that does the work. From memory I used 10% solution and prior I'd tried WD40/GT40 and other lubricants so I found it didn't start to work as I expected. In total it took about ten applications to turn the seat post into tin-foil degraded mush. I suspect it took a while for the caustic to degrade the grease/oils before it properly got-going. I had a bung in the seat tube and applied via syringe into the bottle braze-on so I only got it in the seat post area, frame upside down and angled to protect as much of the rest of the frame as possible. Try to keep it off the paint as metallic paints have some Alu content I hear, rinse off with water if you get spillage. You must use safety glasses, I had caustic in an eye in 1979 and the pain was unimaginable and was lucky not to be blinded. On top of this, it generates A LOT of heat when it gets going properly, could have an effect on frame metallurgy...? I found that once the heat died down it was spent, I suspected anyway, so I dumped the contents and re-dosed. You need to be really careful with caustic, do the whole PPE thing as it is dangerous... best of luck & be careful.. ATB

Thanks for the tips. So from the sounds of this, I'm thinking that if I go the caustic soda route, I'd be better off drilling out the the bearings and spindle first and degreasing the hell out of the bottom bracket to try to get a reaction in the first or second attempt. Unlike a seatpost, the aluminum cup and threads in the BB are pretty thin so hopefully the BB doesn't need as long of exposure vs a thicker seat post

 

[FluffyChicken]

Hydrochloric acid will neutralise it safely.(ish) other acids will also neutralise it too, if needed.

if you're drilling you axle etc out, you may find you can score the shell with a saw (junior hacksaw blade) and then crack it out from the side with a thin blade screwdriver/chisel/etc and a hammer. I did that in my Alu-O where NaOH/KOH wasn't a useful method.

 

[90's Ninja]

That will be the next step and yes, I will try to carefully blade and chip away first. Then the big caustic guns have to come out as I don't want to give up on this frame...yet

 

[BOBU]

Apologies.... thought you were doing a seat post.... RTFM for me. Best of luck - ps I wouldn't try to neutralise with acid, if it's not spent caustic you'll get a super violent reaction acid/base!!

 

[FluffyChicken]

It'll not be that bad. You don't use conc acid.

End up with water and table salt (or Lo-Salt if KOH), the salt they use to claim the product contains less salt.