Caustic Soda - no reaction

[Tolsey31]

Hi,
I tried the caustic soda to remove a mangled seatpost but didn't get the reaction I was expecting...nothing happened. It's an alu seatpost in steel frame. I didn't have it open to the elements so I'm thinking that oxygen may be a part of the reaction? Anyone with the science chops for this please?

 

[Suprachrgd82]

NaOH will react with aluminum, guaranteed. There are some things that will quell or prevent such reaction; oil, grease, wax, anodize coatings, paint, residual oxides, weak NaOH solution, etc.

Is there adequate accessibility to scuff the inside of the post and hit it with degreaser?

 

[Tolsey31]

It's pretty mashed up inside the tube - maybe the solution wasn't strong enough - I used about 70g soda to 0.5l water.

 

[Suprachrgd82]

Agreed, you’ll likely need >4x that concentration to get expedited results.

 

[Tolsey31]

Thanks for your input - I'll try again tomorrow

 

[FluffyChicken]

Pile a load of the crystals up around the post etc and get some boiling water, poor some of that on it slowly.

Take whatever precautions you need after a few beers in the sun while you do it.
I'll leave you to the risk assessment.

 

[Suprachrgd82]

Wear gloves and glasses. NaOH can do horrible irreversible things to soft tissue.

 

[Tolsey31]

Yep, I was fully protected earlier when nothing happened! Will be same again

 

[novocaine]

Acid to base to safe your face.

 

[Tootyred]

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