Cleaning copper rivets.

[James Hall 3Participant @jameshall3]

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.

[James Hall 3Participant @jameshall3]

How to ensure rivets are clean enough for silver soldering boiler.

[JasonBModerator @jasonb]

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

[Jeff DaymanParticipant @jeffdayman43397]

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.

[Brian HParticipant @brianh50089]

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

[Former MemberParticipant @formermember12892]

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[Tony Wright 1Participant @tonywright1]

A method I saw ,was to get a small jar ,fill it half full of pickle (white vinegar will do) next get an old table spoon put a few rivets in the spoon ,heat them to a dull red then pour them into the pickle. Result clean annealed rivets! Ready to use.

[James Hall 3Participant @jameshall3]

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?

[Former MemberParticipant @formermember12892]

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[DMBParticipant @dmb]

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.

[Nick Clarke 3Participant @nickclarke3]

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**

[Former MemberParticipant @formermember12892]

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[nigel jones 5Participant @nigeljones5]

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.

[Nick Clarke 3Participant @nickclarke3]

Posted by br on 13/01/2021 19:42:18:

Anybody know the EXACT rules on sulphuric acid purchasing?

One google site says illegal tobuy if notc in the trade and you need a licence.

Ebay – oneshot , no problem at all – just bought some a few moments ago as this thread reminded me it was needed.

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.

[Former MemberParticipant @formermember12892]

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[Tony Wright 1Participant @tonywright1]

To the experts don’t read any further ! I use old car battery acid dose the job and have never had any problems with my silver soldered boilers . If it was good enough for LBSC it’ll do for me !

[Robert Atkinson 2Participant @robertatkinson2]

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.

[James Hall 3Participant @jameshall3]

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?

[Former MemberParticipant @formermember12892]

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[Nigel Graham 2Participant @nigelgraham2]

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.

[SillyOldDufferModerator @sillyoldduffer]

Posted by br on 13/01/2021 19:42:18:

…

PS Nick Clarke -I admit to not having a goverment licence.

…

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

[Former MemberParticipant @formermember12892]

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[Former MemberParticipant @formermember12892]

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[not done it yetParticipant @notdoneityet]

I would have thought everyone would have realised that lead acid batteries do not dissolve away in the sulphuric acid electrolyte!

For others (readers🙂 ), lead sulphate is only a tiny bit soluble in water so the solubility product (ionic product) is very low. That will mean that the high concentration of sulphate ions in the electrolyte will depress any likelihood of lead dissolving as lead sulphate to effectively zilch. Lead sulphate and lead oxide have fairly high densities so as long as the electrolyte is allowed to settle, before use, any lead from the battery will be found as insoluble sediment.

[Keith HaleParticipant @keithhale68713]

Fizzy is bang on!

It matters not how clean the rivets are when assembled, it matters only how clean they are at brazing temperature 660 °C. AND THAT IS THE FUNCTION OF THE FLUX. All you need to do is make sure that the components are free of oil and grease or anything else that will prevent capillary flow of the filler metal.

To be successful, I suggest that you appreciate what to do and why when brazing/silver soldering. It is a very simple process but skilful. Not acknowledging that will inevitably lead to problems, maybe not now but certainly in the future..

Several companies produce excellent data and information. Use it. Don't trust salesmen? Read the information in the form of BS 13424.

After all, if you want help with the selection of your Sunday roast, do you ask the person behind you in the shop or the butcher?

Regards

Keith

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