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Cleaning copper rivets.

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

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James Hall 313/01/2021 18:41:10
35 forum posts
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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.

JasonB13/01/2021 18:44:35
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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 Dayman13/01/2021 18:45:19
2061 forum posts
45 photos

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 H13/01/2021 18:48:12
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2034 forum posts
111 photos

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

br13/01/2021 18:50:03
458 forum posts
3 photos

As Jason above, just leave them in the pickle overnight.

I use one shot drain cleaner at 10%.

br

James Hall 313/01/2021 19:09:35
35 forum posts
8 photos

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?

br13/01/2021 19:13:27
458 forum posts
3 photos

Vinegar as Tony says.

Sulphuric pickle and dull red rivets is a definite NO.

Forgive me for stating the obvious, but it seems to be a new area for you from your post above, so better safe than sorry.

br

ADDED.

Citric is safer to use 

Sulphuric solution is more effective at removing the flux / residue .

 

Edited By br on 13/01/2021 19:16:53

DMB13/01/2021 19:22:39
1062 forum posts

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 313/01/2021 19:31:30
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1091 forum posts
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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**

br13/01/2021 19:42:18
458 forum posts
3 photos

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.

  • Contains 91% strength sulphuric acid

br

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

Edited By br on 13/01/2021 19:43:26

fizzy13/01/2021 20:16:13
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1766 forum posts
120 photos

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 313/01/2021 20:30:52
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1091 forum posts
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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.

br13/01/2021 20:34:32
458 forum posts
3 photos

Thanks for pointing it out Nick - did not register with me initially.

br

Robert Atkinson 213/01/2021 20:46:57
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902 forum posts
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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.

James Hall 313/01/2021 20:51:14
35 forum posts
8 photos

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?

br13/01/2021 20:58:30
458 forum posts
3 photos

James Hall.

I hope there is not likely to be a problem.

br

Edited By br on 13/01/2021 20:59:22

Edited By br on 13/01/2021 21:13:28

Nigel Graham 213/01/2021 21:49:03
1059 forum posts
16 photos

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.

SillyOldDuffer13/01/2021 21:49:14
Moderator
6866 forum posts
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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

br13/01/2021 21:50:45
458 forum posts
3 photos
Posted by Tony Wright 1 on 13/01/2021 20:34:58:

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 !

Old car battery acid must contain lead? Not too sure about this ?

br

br13/01/2021 21:54:54
458 forum posts
3 photos

Dave

In simple terms, anybody buying one shot, as I have just done tonight, without a licence, is breaking the law ?

br

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