Pickling Copper and Brass

[Tiggy_dorset]

Not sure which section this belongs in. It comes under metal finishing, so I think it may be the most appropriate section.

Anyway, I use Sodium Bisulphate for pickling copper and brass, after soldering. Ths is the stuff Im currently using.

http://www.poolmarket.co.uk/water-balancers/blue-horizons-ph-minus-granules-25kg-218.html

I like this, as it is the cheapest I have found so far and I do make a profit on the items that I clean. I know there are better chemicals for the job out there, but this stuff can be diluted and poured away.

My question though, Does anyone know of a fairly priced, better chemical for the job without the problems of disposal?

Cheers

 

[chunkolini]

I remember as a kid soaking pennies in vinegar for a few days and they would come up lovely.
That might be a good starting point.
Effectively a dilute Acetic acid.

 

[Tiggy_dorset]

I remember as a kid soaking pennies in vinegar for a few days and they would come up lovely.
That might be a good starting point.
Effectively a dilute Acetic acid.

a few days in vinegar compared to 40 minutes with the bisulphate

However, I am now researching Acetic acids which may prove to be promising, so thanks for that

 

[ps_bond]

Citric works relatively well. Sulphuric acid at 10% works (add acid to water, never water to acid); I've used cheap drain cleaner (96% sulphuric) diluted down before now.

I've used brick acid to take galv off, never tried it on non-ferrous; ISTR some diving friends using it on lumps of brass to get the concretions off.

Neutralise the stuff before disposal - and remember what's dissolved in is copper salts, so less than ideal in the water table. The usual suggestion is to neutralise, evaporate to dry and then dispose "appropriately".

 

[Tiggy_dorset]

Some items need to be nickel plated after. Are there any pickling acids to be avoided because of interference/reaction to the plating process?

 

[MattF]

Check which acid is used in that Cillit bang, (the stuff which had the adverts with the annoying gobby bloke), or whatever it's called. Not sure if it's phosphoric? That apparently cleans up copper based metals well.

 

[hotrodder]

Rhubarb (stop laughing!) was apparently the hot ticket for cleaning copperware in days gone by. It contains several different organic acids including citric, oxalic, acetic and others i can't remember

 

[Will_Davis]

For pickling copper model loco boilers and the like I used to use battery acid drained from old car batterys. Maybe these days not the best 'Elf'n'Safety choice.

Much safer is Citric Acid ( aka: conc. Lemon juice ) This also does the job.

HOWEVER: Even though citric acid is potable ( in low concentations like lemons and oranges ) by the time its pickled silver soldered copper boilers its now a HazChem!. Please dispose carefully

Will

 

[ps_bond]

Some items need to be nickel plated after. Are there any pickling acids to be avoided because of interference/reaction to the plating process?

No experience there, sorry - gold and silver have no problems being plated after pickling, but that's not nickel.

 

[ouchmyfinger]

Before soldering a radiator tank or repairing the core, we would pickle (clean) it in 100% hydrochloric acid, i dont know if they still use thst stuff now, then all we would do after soldering, is wash the acid, flux and residue off with soapy water, wire brush it and dry it, we did,nt have neutralisers back in my day, we would then spray the rad.
paul

 

[ps_bond]

Bicarb I buy mine in stupid quantities from the local Chinese grocer.

 

[ouchmyfinger]

Bicarb I buy mine in stupid quantities from the local Chinese grocer.

Why spend money when soapy water will do......

 

[ps_bond]

Fair enough for washing pickle off - although I usually only neutralise closed objects - but it's no use for neutralising waste pickle prior to disposal.

 

[ouchmyfinger]

Yes sorry, i was relating to neutralising the metal and solder joint. For the waste i believe sodium hydroxide is used nowadays to neutralise hydrochloric acid but back when i was repairing, we had never heard of or used any agents.

 

[Tiggy_dorset]

Thanks for all the replies guys.
I have been reading some comments on another forum on the subject. The general consensus seems to be that the bisulphate that I am currently using is the most widely used method and the safest.
Sulphuric and hydrochloric are fiercer, although they do have the advantage of still working well at low temperatures. I have ruined endless ammounts of jeans from using battery acid when filling batteries in an old job, in the past, so I know how potent the stuff is. I may stick with the bisulphate for now and just improve it with a heated tank, maybe agitate it as well.
I am still yet to fully research the Citric route though.

 

[linuxfreak]

Copper cooking pots were cleaned up with 1/2 a lemon dipped in salt back in the day. Brightens them up nicely.

George

 

[Tiggy_dorset]

Disposal

Please correct me if I am wrong anywhere...

As I understand, Citric acid is relatively safe to dispose of down the drain, but does it need neutralising/diluted first?

If it has been used for pickling copper, its the copper content which will make it unsafe for disposing down the drain. Will it be safe, if it has been used for pickling mild steel? or is mild steel as environmentally un-friendly as copper?

Cheers

 

[chunkolini]

When I spoke to the people at Bilt Hamber about their Deoxy C rust remover which is basically Citric Acid they said 'after cleaning steel it is fine to go down the drain you could even drink it'.

 

[Tiggy_dorset]

When I spoke to the people at Bilt Hamber about their Deoxy C rust remover which is basically Citric Acid they said 'after cleaning steel it is fine to go down the drain you could even drink it'.

Thats good enough for me, thanks Chunko

 

[MattF]

Regarding the citric acid and brass/copper bit, check out the Yank gun forums. Seems to be quite widely used for cleaning up spent cartridges, along with tumbling.

Been testing it on some brass here recently, and bar the fact that you can get the patchy copper/brass effect which needs polishing out, it does a decent enough job of cleaning the stuff. If you dunk owt in there which has oxidised notably though, it will be pitted once the citric has removed the corrosion.

Regarding steel, you basically end up with a mildly acidic iron rich solution. Some plants will love that.