Nexuas

Does anyone know what strength of citric acid solution I need to clean some copper?

I have to make up 80litre of the solution to be able to dip the copper object I need cleaning. I went to the local homebrew shop and purchased 1.5KG of E330 Citric acid, got it home to find no instructions at all on the packet, how much do I need to use, The object need to be perfectly clean at the end, but I would not like the acid to eat it away?


Bit of background...

I have purchased a model steam train with a copper boiler, the boiler has some leaks and so requires some soldering work to be carried out, I have been told that citric acid is the stuff to use and to pickle the boiler for a couple of days in the acid solution before taking it to the guy who will be doing the soldering...

Nexuas

In case any one is interested this is what I am trying to repair to be able to run.



3 1/2" gauge.

StickyMicky

try useing coke?

as in the drink?
im sure i cleaned up a few dodgy looking pound coins a while back with sum cheap asda stuff

duSTI's PA

Use Lemon Juice , works wonders on copper pans

Nexuas

80 litres of lemon juice is a fair few lemons. The cleaning agent in lemons is citric acid.

I have the citic acid, just need to know the quantities I need to mix...

duSTI's PA

Sorry did not read the 80 ltr bit

I'll leave now

root

If you believe this about a 5% solution (5 grams of citric acid to 100ml water) should do it although it will vary on the temp etc.

Assuming 80l @ 5% you will need 4kg of citric acid.

The Zohan

Not sure on the quantities but the loco is a cracker!

Nexuas

Bugger!! I purchased 1.5KG as this was all they had in the shop, and I had to go North camp near Farnbrough to get that. Anyone know anywhere in Reading that sells powdered Citric acid?

Cheers Paul, it is a fantastic model. Unfortunatly I can not lay claim to building it. It was built by E G Bareham, I believe he started it in 1967 and finished it in 1980. He ran it till 1991, when the water level in the boiler was allowed to drop and damage was caused. He repaired it, but it was never formally tested, and has not been run since due to the guy's old age. I purcahsed it through E-bay, but have felt the purchase was a little unfortunate. I was assure the model was in full working order, but when I got it home and tried to pressure test it I found the boiler had a couple of leaks which are totaly unrelated to the repair conducted after the loco was last run. I phoned the guy and explained that I was not happy as the loco was not as advertised and gave him two options, either I return it and get a full refund or we negoitate over the price, I really wanted to keep it so pushed for a negotiation and got an amount knocked off. I did not chase the refund in anyway and waited for him to contact me, but when he did I got the cheque and a really stroppy letter telling me how I demanded a refund once I had taken possesion of the model etc... It is a real shame as the old guy was very nice and I think was very sad to see it leave, I was hoping to send him some photo's etc once it was back up and running, but he as told me never to contact him again. I feel quite bad as I never intended to try and rip him off, and I was just disapointed as I had been assured it was in working order...

Hoping to get up and running in time for the centenery celebration on the WHR(p) when the full sized version of RUSSELL celebrates it's 100th birthday.

Ken 275

For passivation of stainless steel ie. to make it inert, a solution of 10% citric and a splosh of conc nitric does the job in 24 hours. A weak solution of tannic acid (~1%) will do the same.

I'm not sure about copper so I would err on the safe side and go for 5% E330 and see what happens.

Good Luck!

K.

Nexuas

Well I have put the 1.5kg in to start with and have dropped the boiler in. I stirred the solution up with a piece of copper pipe, and after a few minutes stirring there was a definite change in colour between the half of the rod in the solution and the half I had been holding, admittedly this was a lot less dirty than the boiler which is covered in soot in the firebox and on the front throat plate which is where the repairs have to take place, but this is an encoraging sign, I will leave the boiler to soak till christmas eve, then will have to take it out as I have to take it to my parents on Boxing day so it can be taken to be repaired between Christmas and New Year.

Simon C

Mate, even if you 5%, just leave it in for a little longer, the concentration usually just determines the speed.

But Acetic (sp) acid (vinegar) will do the same job, its what I used to clean up the alternator belt cover on my car before painting it.

Ken 275

When the job has finished, vinegar will remove the citric (advisable) but must be followed by a good rinse in soft water. This should arrest the process and stop any further deterioration as after all that's what you're doing.

K.

alcazar

iTrader: (2)

I'm not sure the citric acid will have much effect on the soot, either, as soot is mainly carbon.

I'd have been inclined to give it a good scrub with a stiff toothbrush, or even a small wire brush and plenty of Cif or other abrasive cleaner, to remove the DIRT before starting with citric acid, which will remove limescale, and other assorted copper compounds.

As regards the old feller: if you feel bad about it, send him his refund back, with a nice covering letter and an apology. I know just how touchy these old guys can be: my old boy is 91 next year.

Alcazar

Nexuas

The refund was to cover the cost of getting the boiler repaired. I was assuming we were negotiating, as I gave him two options and in the end I aggreed to the price he said rather than me forcing him to the price I suggested. If the repair costs less than the refund, then I will send him the difference back. I think he took it as I was critisising his model building ability, which I was not in anyway as the model is to such a high standard, way beyond anything I could personally achieve!!!!

Gidney&Knowlesy

Coke & Brown Sauce work very well, left over night

Nexuas

It has been in the 2% citric acid now for about 18 hours and there is some difinite progress, I got it out before lunch and gave it a bit of a scrub with an old tooth brush to try and get some of the soot off the end, and this seams to have shifted some, so have re imersed it and will give it another scrub tomorrow...

Nexuas

Scrubbed again and reimersed, seams to be coming up well...