Verdigris removal Via firing

If you are against heating the coin then there is no need to read on, if the verdigris is bad then you have nothing to lose.

The coin will need to be held by a very small ended clamp like tweezers or lockable forceps and its grip must be very little pressure on the coin but enough to hold it still mid air without dropping it, no more than 2mm should be holding the coin, it also MUST be held vertical and not horizontal/flat.



 You will also need an adjustable blow torch.



give the coin a gentle clean with a soft toothbrush and a little soap/washing up liquid, Rinse thoroughly and pat dry.

clip the coin with the forceps and then pass the flame on lowest setting across the coin left to right slowly to about 3cm either side of the coin, when it is beginning to work and the coin heats up you will start to see a green haze or green flame leaving the coin, that is the verdigris burning off, that is your cue to hold the flame/gun on the coin for 3 second bursts, then off the coin for 2 seconds and repeat, the coin at this point can easily glow red, no warping or bending damage will occur.



If you use a butane camping torch which attaches to a small canister which is free standing, you will find passing the coin over the flame much easier and you can rotate the coin very gently for each pass with no damage.

 (Contrary to belief, copper does not always burn green under a flame unless it is copper filings, coins are compressed copper which reacts totally different, verdigris consumes the copper making it brittle)

 as soon as the verdigris is gone the flame will then turn orange, that's when you stop firing or you will damage the coin if it is done more than 10 or so seconds, Quench the coin immediately in Hot water, While it is glowing red hot will give the best results but never let it glow longer than 3 seconds.



Next get some baking powder (not bicarbonate of soda as this type is lightly abrasive, baking powder as it is will dissolve) mix with a little water deep enough to cover a coin with a 50/50 mix ratio, pick your coin up with the forceps and release the coin into the soda solution, leave it there for a good half hour.

Now you can pick the coin out by the rim/edges and gently use a toothbrush dipped in the soda solution the coin was soaking in and gently scrub the coin to remove all residue.


Voila, verdigris free coin as well as a clean coin which retains its patina (if you have done it correctly), even though you will be left with pits if the verdigris was bad, if it wasn't too bad then it will be pale black dots.

My donor coin was severely coated with verdigris, just to show even the worst cases can be dealt with.



Sorry if my explanation seems confusing, not very good at explaining a tutorial.  

I also reiterate, do not do this on really valuable coins, this method can go very wrong if a step is not completed correctly leaving you with a destroyed coin which cannot be reversed. I have 20 years experience dealing with copper in this manner with electronic components from satellite systems (coin size contact pad reworking), My usual method is by using a heat gun and not a flame, I have used it in this method because the torch is actually safer to use than a heat gun.

DO NOT attempt this if you have no prior experience with a blow torch and its safety precautions.

If anyone yells "sacrilege" for doing this to a coin, I apologise but reiterate it is down to personal choice, my donor coin would have been dead within a year with no chance of survival. verdigris is literally a cancer to copper.

I use heat in a lot of my copper art.

Not that I am arguing one way or the other, but this method does create a scale layer that falls off, sort of like polishing also removes metal, but this (unlike polishing) would be a uniform layer. however it might be worth it, as you have said the coins you are doing are better than when you started.

  Also if you want to slow verdigris or even stop it, coat the coins in gun oil.

  PS I love verdigris, send me your dismal verdigris coins.

I have a coin with verdigris, but I think this method is more than I can do at the moment.

The soaking in the baking powder solution stops the crust/flake coating after a coin is heated and then cooled, I should have made that a bit clearer, particles from the soda will stick the the areas where flaking will occur and then can be rinsed off. Like semi quenching, so the coin is hot but not super sizzling, puff of steam for a fraction of a second.

If you have coins where you have nothing to lose then I am willing to do the clean for you as long as you understand there is always a possibility your coin may not react too well if the verdigris has penetrated deep. unfortunately this fact can be only ascertained once the clean is carried out.

I welcome any verdigris coins so I can perfect several other methods I have. the only cost to you would be posting to me, I will send them/it back and cover whatever the meagre cost is.

fluke, I have an 1839 Isle of Man coin that has verdigris. Let me think about it, and I'll get back to you if I decide to send it it along.

The likely hood of it going wrong is extremely low, but I have to state it just in case. In this case though I could easily replace the coin so you wont lose out. (I assume it is a farthing, half penny or a penny?)

can you post up an image of it?

Certainly, Fluke...



The verdigris on the reverse is the worst as you can see.

If I send you the coin, which I will probably do on 25 July, I'll just give the coin to you. It is not worth the time or effort to send it back, since I live in the U.S. and you are across the pond. The only thing I'd like is for you to post before-and-after pictures on this thread so I can see the results.    

That will be a straight forward removal and the results should be nice and sharp by exposing the detail better.

I will send it back, I would prefer that you see the result with it in your hand with your own two eyes.

Images can be edited.....




See     


 if you have any others you can send them as well and I will return them as well as the postage difference is nothing

I will of course post its progress as well but having it confirmed as the real deal from someone across the pond is a very good thing.

The costs are not important to me, don't worry about that.

Okay, that sounds good to me. I'm get back to you when I am about to send it along.

Thanks

Well, I am putting Fluke's methods to the test. I am sending a coin with verdigris to Fluke for verdigris removal.

Here is the before photos that I just took this morning. After Fluke returns the coin to me I will post the after photos.

 

That way it can be verified it really is cleared and not a photoshop style edit to fool anyone.  

Citation: FlukeThe soaking in the baking powder solution stops the crust/flake coating after a coin is heated and then cooled, I should have made that a bit clearer, particles from the soda will stick the the areas where flaking will occur and then can be rinsed off. Like semi quenching, so the coin is hot but not super sizzling, puff of steam for a fraction of a second.

 This is very interesting to me, I have a lot of experience with quenching copper and different effects you can get with it, and I must try this, thanks for sharing your knowledge about copper. Check out some of my work.

Citation: redsmithstudios

Citation: FlukeThe soaking in the baking powder solution stops the crust/flake coating after a coin is heated and then cooled, I should have made that a bit clearer, particles from the soda will stick the the areas where flaking will occur and then can be rinsed off. Like semi quenching, so the coin is hot but not super sizzling, puff of steam for a fraction of a second.

 This is very interesting to me, I have a lot of experience with quenching copper and different effects you can get with it, and I must try this, thanks for sharing your knowledge about copper. Check out some of my work.

that is really cool!

Making copper bleed colours like that is really nice to watch, its like dropping a stone in an oil filled puddle, rainbow colours radiate outwards. Different heat levels will create different colours. Very nice.  

I received the coin treated for verdigris by fluke. It is now verdigris free! What a difference!  I was considering just getting rid of the coin, but now I am going to keep it. Thanks to fluke. He went out of his way to show that his method works, and it does. Here are the unedited photos I took today.

 

Citation: frncsbrennanHe went out of his way to show that his method works

this has been great, I have learned a lot

I am glad you are happy with it, good to get a fresh opinion from someone who confirms I have removed the verdigris without coin damage.

Thanks for the feedback Frank  

Here's what I've done, cleaned with electrolysis, then re-toned with nic-a-coin.
before:


after cleaning:


re-toned:


the after pics are bad I'll take better when I can :)

Better pics, maybe the obverse needs a tad more toning !

Woh, the toning looked super dark.... Is that liver of sulphur to tone it?

Can't beat that choc colour toning. Nice Job.

Firing takes care of the toning but your way is less brutal.

To be honest with you I only bought the fluid because my primus bottle has ran out. My uncle gets them replaced for free so I need to get it over too him. I don't use it anymore though I think maybe once in the last 3 years "/ how sad ha !

Saving any coin from verdigris is a good thing regardless of what method, as long as the coin isn't messed up, it is worth doing what it takes to save it. Value will be crushed of course, but it can sit in your collection and re tone over the years to come.

Fluke, great post . I have a question please . Once the hot glowing coin is quenched in the hot water , how long do I leave it in the hot water before I put it into the baking powder solution ?