The latest intstallment of my seat post removal:
I was going to send the frame to Mercian, they charge £25 for seat post removal (plus £30 collection and delivery). £55 seemed acceptible. I asked them if they would be using Caustic Soda and they laughed "No chance, we've tried that and it doesn't work, we use a torch to melt it out".
So, now I needed to add the cost of a respray. Suddenly I was looking at £150.
Down to the Hardware shop for some Caustic Soda (£2.90 for 500g)
I first needed to seal the bottom bracket. Blu-Tack works (I tested it overnight in a tub of Caustic solution and it looked unharmed). I wedged a big plug of it up the seat tube (Fnnarr Fnnarr) and secured it with cable ties.
That done I mixed a batch at "drain cleaning Strength" and poured it in. Lots of fizzing, lots of heat and lots of gas. As a control I also left an offcut of seat post in the remaining solution (I wanted to see how effective it was).
Next morning there was still quite a lot of fizzing and the control showed signs of erosion but there was no visible signs that the seat post was any thinner.
Emptied into bucket and repeated overnight. Same outcome. Lots of flaky alloy but it looked as sturdy as ever.
Emptied into bucket. This time, instead of 100g/500ml I just guessed and created my own mix (I reckon about 150g/150ml. Poured into frame and waited. After 2 minutes I had to run to grab a watering can to wash away the bubbling froth pouring out of the seat tube, Holy Crapola this stuff really hated Alloy!.
As fast as I was dousing the frame it was drying out with a white residue, god knows how hot the frame was but I wasn't touching it. After 10 minutes it subsided to a point where I could leave it overnight.
I repeated the process last night and revisited this morning.
My control seat post is now noticibly thin, as thin as a knife blade I'd say (in fact I think some of it has totally dissolved, the sharp edge being it's last grasp onto life).
I emptied the frame and poured some of my "XXXX super mix" in. After the expected Vesuvius period I poked a bit of seat post (a ragged remnant of where I had tried hacksawing) and it fell off, into the frame (wow, it must be getting very thin in there now).
I reckon the procedure will be over tomorrow. Either there will be nothing left or I should be able to poke it free with a long screwdriver.
So that's about it. I masked off my paintwork with Duck Tape but I doubt whether that will have done much as the extreme heat melted the adhesive. I'll know more when I've had a chance to clean it.
This process has taken a week in total but I reckon it's a 4-5 day process using a strong mix.
Final report tomorrow hopefully when I assess the damage.
Note. Steel Frame / Alloy Seat Post. This is not something you would do with an alloy frame (unless you thought the frame tubes were annoyingly thick)