Hi Bernard Use Ferric Chloride solution it munches steel faster than it munches copper

Regds

Dick

I broke a tap in my boiler, and removed it using Alum. It took quite a long time, but it leaves the copper and brass /bronze completely undamaged. It works quicker if it's stong and hot, but in my case it was on the backhead bush, and I had to mould a litttle plasticene container round it to hold the Alum, it wasn't possible to keep it hot.

Yes Ferric Chloride does dissolve copper. But here we have a combination of copper and steel is a little galvanic cell . Galvanic corrosion occurs with the steel acting as the ‘Wasting anode’

Rdgs

Dick

I would go with the alum, I removed three broken 8ba taps from some bronze cylinders, placed the cylinders in a pan of saturated alum solution on the stove and simmered, add a spot of water as the solution evaporates.

Two hours and they were gone.

Alum is cheap and leaves the copper/bronze untouched.

Keith W

Neil, go to the garden shop, you might have to buy a Kg of it, but it won't cost a great amount. A few years back I needed some to get some rusted screws out of a brass casting, so I went to the chemist, he was able to get some in a few days later. Awee while later I found that mum had a bag of it in her gardening chemicals cupboard, its been there a good many years, and cost less than a dollar for a 2Kg bag. Ian S C

In the UK try 'oneclickpharmacy' where I had 500g of crystals. They were a little slow in delivering however. Also for smaller amounts (200g) try 'kitchen-chemistry' on ebay.

Sid,

Re "it took a long time". If I remember right, it took about 3 weeks, but I had plenty of other things to do while I waited. Keiths post was interesting, I didn't realise it could be done as quickly as that. But I couldn't boil it like he did, I only had a few CCs in a plasticene cup. I also used a saturated solution, but is that the best strength? Maybe the chemists among us would know.

Phil,

As a very rough rule-of-thumb, a chemical reaction will double in speed with every 10 degree (C) rise in temperature, so from 20 degrees to boiling (100) it should be about 250 times faster. (Please don't regard this as a precise measure, there are many exceptions!)

David

What Ian said…. but 2 minutes on Google came up with :-

Anglia Precision, Peterborough, 01733 703230

Rivercircle, Peterborough, 01733 315101

Qualitetch, March, 01354 658787

Personally, I built one, but thats probably because somebody said I couldn't, or it might have been shouldn't

Andy