Which approach next - *Caustic soda victory!*

Jussa":1sk2wzts said:

Well it worked, admittedly the engineering company made it look easy but then it's their job

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result

Well, I took the frame a couple of places, but no-one seemed confident at being able to machine it out, given the amount of seat tube in there and how far down it is (I think there's about 200mm in there by my measurements).

Soooooo ...... caustic soda it is!

I bought some on my way home today, so as soon as someone gets here to document it on video - off I go!

I actually only bought 500g of caustic soda, because I forgot to check how much I needed and since the shop is shut, I may have to finish the job tomorrow night.

Update with video to follow!

Success!!!

http://youtu.be/-dYnSVVDxrE

I'm glad I decided to take this approach in the end. It was cheap, very effective, easy and most importantly fun.

If you have a seat post that's resisting all other attempts to remove it I'd recommend caustic soda.

It's ideal if you are going to have the frame repainted anyway, but if you intend to keep the paint job I wouldn't necessarily rule it out, as I easil;y could have prevented it going on the paint if I had needed to and hadn't been enjoying it so much.

Where did you get that "Bartoline" caustic soda? A hardware shop? It looks like proper strong stuff unlike the weak soda I got on the high street!

Great for cleaning chains I've found.

Great video. How smooth is the seattube now? Have you tried putting a seatpost in?

I think the Bartoline stuff is from B&Q.
The hotter the water is when you put in the caustic soda the strength raises exponentially. It is very dangerous though and produces a very violent reaction. you need a face shield, goggles, gloves and non-fabric apron etc and it should be poured in from a distance. If put into water when it's near boiling it will explode.

lrh":35af861t said:

Where did you get that "Bartoline" caustic soda? A hardware shop? It looks like proper strong stuff unlike the weak soda I got on the high street!

Great for cleaning chains I've found.

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I got it in my local general shop, 'Super Value' in Cottingham, for £1.50 per 500g container. I bought 3 so that I would have plenty, but one was enough to do the job. I did put a little bit from the second container down, just to check if there was any aluminium residue left, but there was no reaction at all.

coomber":35af861t said:

Great video. How smooth is the seattube now? Have you tried putting a seatpost in?

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Thanks I tried the correct size seat post this morning and it goes in fine. The inside is smooth, with no trace of aluminium left, though I'll probably give it a final clean before I use it.

Rampage":35af861t said:

I think the Bartoline stuff is from B&Q.
The hotter the water is when you put in the caustic soda the strength raises exponentially. It is very dangerous though and produces a very violent reaction. you need a face shield, goggles, gloves and non-fabric apron etc and it should be poured in from a distance. If put into water when it's near boiling it will explode.

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I would not recommend anyone mixes the caustic soda with warm/hot water. The hydration of sodium hydroxide when added to water is highly exothermic and pretty rapid. The squash bottle I was using got melted out of shape by the heat and I'd probably suggest stirring it in, rather than shaking it to mix it, as I did in the video.

Also, as a note, if you are intending to try it, make sure you are adding the caustic soda to the water, not the other way around, as that would also react dangerously quickly.

...I was actually shying away from the screen when you started shaking that bottle! :shock:

A little light reading...

Rampage":3po3ysph said:

I think the Bartoline stuff is from B&Q.
The hotter the water is when you put in the caustic soda the strength raises exponentially. It is very dangerous though and produces a very violent reaction. you need a face shield, goggles, gloves and non-fabric apron etc and it should be poured in from a distance. If put into water when it's near boiling it will explode.

Click to expand...

Meh, health and saftey wombles take all the fun out of life