Been using the frame as lever and seat post in vice, to the point I can see the seat post twisting.

Tried boiling water poured onto the frame

Is there a chemical I can pour into the frame or some other solution

Help appreciated

There are various proprietary corrosion breaking compounds like PlusGas. However if it were me I would be aiming to fill tube with diesel and leave it at least overnight, and ideally for a few days (worth gently shaking or tapping it every so often to help any air bubbles get out. If that doesn’t work then I’d be looking at drilling the old post out very carefully.

I was thinking plus gas. Haven’t seen diesel suggested before. What’s the thinking behind diesel

Caustic Soda mixed with water will dissolve an alloy seatpost and not damage the steel, it’s unpleasant and any spills will dissolve flesh and bone.
There are You Tube videos of the process.
https://www.youtube.com/watch?v=GR9DKMuctTE

Or try this chap?

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TheLittlestHobo – Member
I was thinking plus gas. Haven’t seen diesel suggested before. What’s the thinking behind diesel

Quite commonly used by people in the marine industry to get seized stuff apart. Some people swear its better than plug gas – although I think it may just be cheaper and work in much the same way.

I’ve a Thomson that’s been in my (steel), Niner for a while.
Have tried Plusgas but no avail.
Next up is that spray plumbers use to freeze pipes, inside the seatpost, & heat on the outside of the seat tube; to try to break the hold.

Have you tried asking your wife to have a go?

The reverse jam jar law, innit?
‘I must have loosened it for you, love.’

Get some caustic soda in their and leave for a few days, it worked for me.

Hammers!!!! Go to town on it

Coca-Cola! Honestly! Has to be the full sugar version though.