Treating bronze disease ? George III evasion halfpenny

[JLS 210]

Anyone got any tips on how to remove bronze disease from this unfortunate coin ? I imagine stripping the surface (using bicarbonate ? ammonia ?) would be better than leaving it rot, but I'm wondering if there would be any way to keep the patina. There doesn't seem to be much pitting under the corrosion. 

 

https://imgur.com/a/8BmsnPt

[Paddy 1,869]

I can't say what would be the "right" answer. Obviously it is copper rather than bronze at that age, and that may affect things.

I did strip a pre-1860 Victoria Halfpenny with a similar problem. The most effective was Ammonia, but as you would expect it was left looking very bare and "pink". I found treating with mineral oil (I used 3in1) and leaving in direct sunshine for several weeks brought the colour down to something more acceptable.

Might be worth experimenting with a junk Vicky copper first.

 

[Ukstu 450]

Some people say soak it for a period of time in distilled water then pick at it with a tooth pick and finally soak it in acetone. I've tried this method and had some success and some fails. I am currently trying Verdi care on some coins and have had good results so far but it's too early to say if it work's in the long term. The problems may return over time.

[JLS 210]

2 hours ago, Paddy said:

I can't say what would be the "right" answer. Obviously it is copper rather than bronze at that age, and that may affect things.

I did strip a pre-1860 Victoria Halfpenny with a similar problem. The most effective was Ammonia, but as you would expect it was left looking very bare and "pink". I found treating with mineral oil (I used 3in1) and leaving in direct sunshine for several weeks brought the colour down to something more acceptable.

Might be worth experimenting with a junk Vicky copper first.

That's very interesting. Do you have before/after photos of the copper halfpenny ?

[Peter 615]

Verdi care is the stuff you want. Quite expensive If you research it there are many before and after examples.

[Paddy 1,869]

Yes to some extent. It had not been my plan to make this an experiment so I failed to take full pictures before I started. Here are partial "before" pictures:

[Paddy 1,869]

... This is what it looked like at the end of cleaning and before retoning:

[Paddy 1,869]

... and this after retoning to some extent:

Not perfect but a lot better than it was!

 

[Ukstu 450]

Verdi care....before & after. Sorry about the picture quality it was just to record the results. 

 

[Mr T 189]

I've used a pin/needle combined with little drips of vinegar on the end of a tooth-pick - all very carefully.

[mick1271 159]

11 hours ago, Ukstu said:

Verdi care....before & after. Sorry about the picture quality it was just to record the results. 

 

Did you soak it in the verdi-care , and if you did ,how long .I have had noticeable results with it , but nothing great . I normally clean with acetone ,rinse and dab with verdicare .I have been worried about leaving it for any more than a few minutes .

[Ukstu 450]

It was given two applications. I pooled it on it for about 40 mins then took the toothpick to it to pick off / scrape at it. Once i was satisfied I'd got it all off I washed it in acetone then pooled it on again and left it for around 40 mins before dabbing it dry with a cloth and leaving it to air dry completely for 24 hrs. 

That coin above has had two previous unsuccessful treatments with distilled water and acetone. Each time it's broken out again within a few months. I am hoping the verdi cares stopped it it now. If not I'll just have to try again. It's been a week since treatment and all's okay so far. Fingers crossed. 

 

Edited December 31, 2018 by Ukstu

[jelida 1,374]

I have on occasion left the coin overnight with a pool of Verdicare over the verdigris, this helps it soften and does not affect lustre or toning. Prodding the verd with a sharpened cocktail stick periodically is essential to free up the softened verd. I occasionally use a needle under the binocular microscope.

Jerry

[blakeyboy 1,811]

The trick to this is to _always_ use a 'pick' that's softer than the metal/alloy of the coin.

Using something made of steel is quite a risk.

On bronze this is easy- any old bit of soft copper wire that has the end shaped will do the trick.

Re-patinating is tricky with bronze, since it's less reactive than copper- raising the temperature is the key.

Sliding the coin into a fluorescent lightbulb that's base down and on a lot keeps the coin at about 45-50˚C,

thus speeding up patination- six months as opposed to years....

Clean the coin with alcohol first, keep fingers off it, and rotate it regularly to get the air to the surfaces evenly.

Works beautifully.

 

 

 

 

 

 

 

[Varietalis 20]

Does anyone have any vericare to sell?  I probably only need 0.5ml as the spot I'm looking to improve is very small.  Alternatively, is anyone able to look at verdicare treating the spot if I send them the coin?  PM me and I will send you a photo of the area.  Many thanks in anticipation.