Cleaning copper rivets.

Having decided that I'd acquired some basic skill in the use of my new SC4 I thought it time to actually embark on making something - so bought the enticingly titled Stan Bray book on making simple steam engines and boilers.

For a simple boiler he recommends copper rivets to hold the boiler end plates in positioning while silver soldering - hmm, I thought, good idea and nicely decorative too - so drilled all the holes and bought some 3mm copper rivets.

BUT - 3x4mm rivets are too small to hold in my fingers to get them bright clean (they are dull copper, not shiny, but not visibly dirty either) - what do I do to clean them up? I could soft solder them in place after the main soldering job using active flux - but that would make a nonsense of silver soldering the rest of the job!

Any suggestions from the old hands would be very welcome.

Two asides: I was in a nasty traffic accident a couple of months ago, injury compensation is at an early stage but just before Christmas my replacement car arrived courtesy of the other driver's insurance - funny thing, but it looked more like an SX3 mill than a Honda Accord. Every cloud has a silver lining. Second, building my first engine (Slim Sam for those who know the book) have found fatal errors in the plans - more of this in another post.

You will no doubt need an acid pickle to clean the boiler at various stages during construction and that will also clean the rivits.

Pickle to clean rivets (either citric acid or sulphuric acid solution)

Don't use ANY soft solder on a boiler, too many potential issues, silver solder and you will be fine.

I always wash them in soapy water to remove any oil or grease and then give them a pickle along with the plates to be silver soldered.

Please let us know how you are getting on with the project.

Brian

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Thanks to all for such speedy replies already received.

I must have been suffering from a misapprehension, I think: that citric acid is used to clean flux residues after soldering - but it seems it is good for cleaning up beforehand. Does the copper need to be mechanically cleaned before 'pickling' i.e., in addition to the obvious removal of any oil or grease?

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Soft solder will prevent any subsequent silver soldering even if the soft has been filed off. It seems to sink into the surface of the copper. Just forget soft solder for boiler making. I think almost any corrosive liquid will remove oxidation and it need not be so aggressive, white vinegar from supermarkets, citric acid from wine making shops or stronger like patio, brick, toilet cleaner. I would rather use the less aggressive acids which take longer but are much safer to use and easier to dispose of safely.

Citric acid, vinegar, drain cleaner all legal, but sulphuric acid 15% w/w or stronger (I still can't get used to calling it sulfuric) is deemed to be an explosives precursor and cannot be bought or kept without a Govt. Licence.

**LINK**

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There is no point to cleaning the rivets as they will revert back to this colour the first time you fire the boiler. Your flux will do the cleaning as far as the joint goes. It is definately against the law for joe public to buy Sulphuric acid above 15% W/W however suppliers routinely sell Drain Cleaner to the public which is 95%, indeed the only difference between this and the stuff they sell to businesses is the label.

The link in my post is .gov.uk so is probably as close to definitive as you can easily get - but as fizzy says a lot of people sidestep the law by calling it something else or totally ignore it as I suspect the ebay seller does.

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The EPP regulatons only apply to the general public, not commercial or professional users.

A lot of drain cleaners and similar products have changed their formulation as a result so take care, the same name product you used to use may not be the same, check before use.

Technically it's now illegal to pour the acid out of a battery and use it for other applications. While the EPP law will potentially make prosecutions easier, like gun and knife laws I think it is unlikely to ahve significant impact on criminal users.

Robert G8RPI.

Tony Wright - I was wondering about using battery acid - got a couple of old car batteries hanging around waiting for the tip to reopen.

Think that I can handle the stuff. Old enough to remember when you could go into the local chemist and buy concentrated sulphuric/nitric/hydrochloric on the way home from school for the chemistry set (and possible other things which we won't go into!).

No problem with the soldering caused by residual lead salts which battery acid is bound to contain, then?

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Household acids (vinegar, citric acid, de-scaler) all fine but I would stress the point Brian H makes -

Degrease the rivets thoroughly first, as grease tends to protect the metal from weak acid and would potentially contaminate the silver-soldering.

Is admitting that on the internet wise? Someone being prepared to sell illegal items isn't a defence.

UK law changed in 2018 after an outbreak of acid attacks. Now it's an offence for an unlicensed private individual be in possession of Sulphuric Acid. Quite serious : 2 years in prison and an unlimited fine. And we can't come and visit because of Covid!

OK for a business to buy and possess concentrated Sulphuric without a licence, but I'd advise a private individual wanting a controlled substance for pickling etc to do the paperwork and get one. I don't think it's difficult.

Dave

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