Nine months in the acid bath!

[nigel jones 5Participant @nigeljones5]

Whilst making a 2" scale boiler for a traction engine mid 2018 I missplaced one of the inner firebox plates, so made a new one and carried on. Yesterday I was forced to extract a boiler from the acid bath by hand (vets full arm glove) and to my suprise came across the lost plate laying on the bottom. I had always wondered what effect long term acid soaking would have on copper. Anything over a day with brass is very bad news – im using 30% Sulphuric Acid so its strong stuff. The plate in question has a little crystalisation of acid salts on its surface but other than that was in perfect condition – I wont be using it but I wasnt expecting it to look as well as it does.

[nigel jones 5Participant @nigeljones5]

[Robin GrahamParticipant @robingraham42208]

Copper is one of the least reactive metals, barring the 'precious metals' – it will react with oxidising acids (eg nitric), but only slowly with others. I believe nuclear waste is buried in copper containers for this reason.

Robin

[Danny M2ZParticipant @dannym2z]

When I snapped a Mills 1.3 crankshaft in a partially turned 2024 aluminium alloy spinner-nut I put it into a plastic yogurt container, covered it with sulphuric acid (battery concentration) and left it in the garden.

After six weeks the steel shaft finally turned to a black powder that was easily flushed out.

There were a few dark spots in the aluminium which had turned gray but it was only on the surface and machined away easily.

* Danny M *

[Brian HParticipant @brianh50089]

That's very interesting. I get in a panic leaving copper in my suphuric acid bath (only about 5%) but from the above I'm worrying quite unnecessarily!

Brian

[nigel jones 5Participant @nigeljones5]

Me too Brian, thought this might put a few minds at rest!

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