Ageing copper

[Kittyhawk]

I have some hard copper shim that I have sanded with emery paper and then buffed on a felt wheel, this to get some fine scratches out. The unintended consequence of this is that the copper is now bright and shiny and I want it to revert to dull and dark. There are various preparations that I can order online to do this, including a certain liquid that we all carry internally which is supposed to work. However I would like the copper to darken naturally which it will do, but is there any way to hasten the process?

 

[Adam W.]

Put it out in the rain. Plumbers hate having their pipe out in the rain as tarnishes and they like it all shiny.

 

[Sachakins]

Best use what we produce freely...

 

[Sandyn]

Ah!!! that kind..... thought you were looking for an old policeman.

 

[Alli]

Have you looked at Antiquing fluid - John Penny Restoration has it on their website. We had to lift some floorboards in a grade 1 listed building that had been down for donkey years due to a leak in the pipe work underneath. The boards had cup pretty badly, so we kerfed the back of the boards and to help get the bow out of the boards. We used brass screws with cups to get the boards flat, but the bright brass stood out like a sore thumb. I got a bottle of the antiquing fluid, you only need a small amount but it ages the screws in seconds, I then neutralised the screws in water, dried them and installed. They now look like they have been there for a hundred years like the boards around them. It says it works on copper though I have not tried it.

 

[Kittyhawk]

Put it out in the rain. Plumbers hate having their pipe out in the rain as tarnishes and they like it all shiny.

The copper is inlayed into timber already so am reluctant to apply anything that would stain the wood so looking for something to speed up the oxidation process - perhaps high humidity?

Best use what we produce freely...

From what I've read it does work a bit but I don't think the customer would be best pleased if he knew I'd peed on his model aeroplane..

 

[baldkev]

I have a customer who is an artist and a while back he told me about his experiments with ageing copper and gold leaf, looked quite cool. I cant remember what it was he used though! A quick google showed this:

 

[Kittyhawk]

I have a customer who is an artist and a while back he told me about his experiments with ageing copper and gold leaf, looked quite cool. I cant remember what it was he used though! A quick google showed this:

I had heard something about ammonia.
The current plan is to mix up a little pot of the ammonia brew according to your screenshot, put the pot together with the wood/copper bit in a sealed plastic bag and leave it in the sun for a while. Hopefully this will create an oxidising atmosphere.
The other reason I don't want to paint the mix on the copper directly is because the metal is so polished that any fluid just beads and runs off and would probably result in a streaky finish.

 

[JimB]

Ah!!! that kind..... thought you were looking for an old policeman.

Dock Green sprang to my mind too

 

[Adam W.]

Careful, amonia darkens some wood, so you may be making more problems as you go along.

 

[Fergie 307]

Use the antique effect fluid and just apply carefully with a small brush so you don't get it on the wood.

 

[Vintage Frames]

As already mentioned, go with the antiquing fluid. The thing to do is to dilute it with water and test what strength gives the desired effect.
Liberon also do the same sort of stuff - called Tourmaline, I think.

 

[Richard_C]

I've used ammonia fuming successfully for patinating copper leaf on turned items.

Ammonia in a plastic pot of some kind, item above it not in it, clingfilm over the top to keep fumes in. I used a margarine tub.

You can vary it by painting on vinegar or salt solution beforehand, each gives a different colour.

Keep an eye on it, one took about an hour but the first one I did went a bit too far in just 10 minutes.

This was on elm which remained unaffected, but other things might be.

Maybe try it with a shined up bit of plumbing pipe first?

 

[Fergie 307]

As already mentioned, go with the antiquing fluid. The thing to do is to dilute it with water and test what strength gives the desired effect.
Liberon also do the same sort of stuff - called Tourmaline, I think.

The fluid appears to turn the metal black almost instantly, however if you quickly wipe it off you find it has only coloured it a little. You can repeat the process to get the desired colour, or with practice estimate how long to leave it to get the colour you want. And somebody, maybe the OP, mentioned water bearing on the surface of the metal, this is a sure sign it is contaminated with something. If you are plating a good test is to ensure that water will wet the surface properly, then you know it's clean. This is a similar process so the same applies, maybe rub it with some weak citric acid solution, or a good scrub with some alcohol. In practice you will find these ageing solutions are fairly forgiving, but I have sometimes found you have to do a couple of treatments before it really starts to work fully.

 

[Kittyhawk]

Thank you for all the replies.
The shiny copper problem is well on the way to being resolved, and by the best possible means - namely leave it alone. The last couple of days have been warm and muggy with humidity around 88% and the copper is heading back towards the caramel colour that I wanted. The next few days are meant to be hot and showery so I expect when it's finish coating time in another 4 - 5 days all will be well.