Brazing

This topic has 12 replies, 11 voices, and was last updated 4 March 2018 at 20:56 by Zan.

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24 February 2018 at 16:02 #343058
alan ord 2
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@alanord2
Hi all, I need some advice. I have just finished brazing the steps and brackets for my Pansy 57XX loco and i need to clean up the carbon residue following the brazing. I have used a wire brush as far as possible but can't get into the corners. I am thinking about pickling them but not keen on using strong acids. I'm sure I have seen something mentioned in the past about using ordinary household products. I know that Cola can clean copper based items and possibly white vinegar or lemon juice. Can anybody suggest a method.

Thanks, Alan.
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24 February 2018 at 16:02 #25834
alan ord 2
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@alanord2
Clean up of steel brackets.
24 February 2018 at 16:07 #343059
Thor 🇳🇴
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@thor
Hi Alan,

You can use citric acid for pickling, that is what I use. Takes a bit longer than sulfuric acid but is easy to obtain, if I have pickled steel I rinse in sodiumbicarbonate solution (to neutralize the acid) and then plain water.

Thor
24 February 2018 at 16:16 #343062
He Who Dares Wins
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@jameswilkinson3
Safety pickle from cookson gold or maybe from Cousins. They are jewellers tools/ suppliers.
24 February 2018 at 20:44 #343085
Samsaranda
Participant
@samsaranda
Alan, I use Citric Acid it takes longer than the stronger acids but is gentle in action, so gentle in fact that it’s safe on your skin, it’s only basically lemon juice but it does the job.

Dave W
24 February 2018 at 21:38 #343093
IanT
Participant
@iant
Alan,

Look on eBay for "Citric Acid Food Grade" – 1Kg will last you a long time and costs about a fiver. Used in Indian cooking I believe… much (much) cheaper than the silly little boxes sold by Chemists.

Regards,

IanT

Edited By IanT on 24/02/2018 21:39:17
25 February 2018 at 09:53 #343132
Ian S C
Participant
@iansc
You can buy a box/packet of citric acid from the home brew shop, that's the cheapest, next place is the super market. If you need it by the hundred weight, an agricultural supply outlet.

Ian S C
25 February 2018 at 11:26 #343144
Keith Hale
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@keithhale68713
Hi Alan,

Carbon deposits – from brazing?

Where did they come from? Not the gas, nor silver solder nor the copper.

Or is it that the flux esidues are black? In this case neither citric acid nor sulphuric will help. A more likely explaination is that the flux has been heated too long or to too high a temperature and degraded.

Use a stiff wire brush or other mechanical means to clean things up. Inspect and test the joints.

Stop it happening again by using a longer life flux like HT5

Regards

Keith
25 February 2018 at 11:37 #343146
Hevanscc
Participant
@hevanscc
Get a cheap kettle and packet of citric acid from Wilkinson. Add two tablespoons to kettle with water and boil. Pour boiling citric solution over components and leave to soak for 30 min. Then scrub with wire brush.
Hywel
26 February 2018 at 15:04 #343285
alan ord 2
Participant
@alanord2
Hi Keith, thanks for your input and I can confirm is it is not The Cup Alloys purchased flux. The brazed joint is one side of the bracket. The whole bracket is discolored black and also has sooty deposits. I did use a wire brush on the accessible parts of the brackets but it is the corners of the steps I can't get at to clean before painting.

Alan.
26 February 2018 at 15:23 #343289
JasonB
Moderator
@jasonb
Keith, I suspect Alan is talking about steel fabrications not the copper boiler. I also find that the steel takes on a black coating on the areas that are not fluxed but being happy to use an acid can get it to come off easily together with the HT5 flux.

This is the sort of black being talked about

Edited By JasonB on 26/02/2018 15:24:19
26 February 2018 at 20:03 #343338
Weary
Participant
@weary
I use path or brick cleaner diluted in water to make a bath – add brick/path cleaner to water. Immerse blackened steel parts and leave until the blackened areas have flaked off. Some gentle abrasion/prodding, etc., will speed things up if desired. Parts are left with a matt grey finish that needs protection against rust immediately upon removal from the cleaning fluid.

In my experience there is no damage to the parts by leaving them too long (overnight) in the cleaning bath.

Regards,

Phil
4 March 2018 at 20:56 #344441
Zan
Participant
@zan
I use sulphuric acid. Very effective at removing the mess it comes off as very thin flakes. Also discovered by chance that it also removes the black mill scale found on thicker steel plate, a tiny rub with the finger will remove it with ease. Obviously take sensible precautions and rinse well. Essential to oil or prime the component straight away or it will quickly gains red colour!

Edited By Zan on 04/03/2018 20:57:33
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