# Gold leaf recovery



## RustyK (Feb 5, 2018)

I have a good amount of 23.5 K gold leaf to recover. 
Some of the leaf is in pure leaf scrap, the rest is mixed with paint/gold size.
We use the gold leaf to gild letters on gravestones which we make. We usually have a painted enamel undercoat prior to putting the gold leaf on with a size. We then scrape the excess leaf which can be a good amount after a year or so.

I have bought a small electric furnace and some borax as a flux. 

I was wondering should I burn off the paint first and will this leave behind a pure enough gold to melt or should I use any any chemicals at this stage with the purity being 23.5K

I am new to this and was wondering if any one can offer advice.

Thanks in advance.
K


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## FrugalRefiner (Feb 5, 2018)

It depends on your ultimate goal.

If you just want a melted chunck of gold to either sell or put away for the future, and you don't really care about the final quality of the gold, you can melt it. But you won't know the final purity, so to some extent, you'll have to depend on the buyer to be able to determine the value and, hopefully, pay you fairly.

One of the reasons many of our members refine their gold is that at the end of the process, they know what they have. When done correctly, they know their gold is at least 99% pure, so if the buyer tries to tell them it's less, they know to walk away.

Gold leaf would be fairly easy to refine, but any refining is still hazardous. You'll have to devote some time to learning how to do it right. Once you melt it, it's a _little_ more difficult because you've greatly decreased the surface area, so the same acids would not work as quickly.

An option is to have someone here "toll" refine it for you. They'll refine it, retain a percentage for their work, then melt the remainder into a nice, shiny button of gold for you.

If you decide you want to learn to refine it, or have someone toll refine it for you, don't melt it.

Dave


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## nickvc (Feb 6, 2018)

With good leaf you need considerable amounts to make the effort worthwhile, the books that it comes in probably has more paper than gold by weight, can you weigh what you have so we can judge whether it’s worth your time and effort or anyone else’s. Over the years I have done quite a lot of this material and it is usually very pure so refining is not always necessary, are you sure it’s 23.5 carat because they usually use fine gold as it’s so ductile.


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## RustyK (Feb 6, 2018)

Thanks guys,

I will look into it. It may be worth getting someone else to do this for us.
We buy the books of 23.5K from a reputable supplier. Some months we could spend up to £400 on the leaf
if we are busy. I would say about half of the gold we use ends up as waste. we usually save it up for a couple of years and then send it away. The last time I reckon we had about 3 oz of loose leaf plus a lot of gold mixed with paint , we didn't get a good deal on it so thought it might be better to refine it ourselves to see what actually would be left.

I did try to melt some down with borax. I could see the gold glowing and melting but once cooled it was more like a black carbon with bit of gold in it which was left. I didn't want to do too much more as to waste it.

I might study this a bit more before taking further.

Cheers


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## goldsilverpro (Feb 6, 2018)

A 3-3/8" X 3-3/8" sheet of 23.5K leaf contains about $0.50 worth of gold, give or take - the manufacturers usually say that 1000 sheets of the higher karat leaf contain from 12 to 15 grams of gold. What they call double thick leaf is really only about 10-15% thicker, if I remember right. Actually, 23K or 23.5K leaf is much more commonly used than 24K, at least for letter gilding. I made gold-leaf hand-carved wooden signs for many years and went through many 500 sheet boxes of 23K leaf. I did use 24K leaf a few times and its application seemed identical to that of the 23K. Here's a few of my signs:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=67&t=6955&p=62441&hilit=gsp+signs#p62441

When letter gilding, I would guess that, on average, about 50% of the leaf ends up as waste. The scrap I ended up with was mixed with paint, size, and paper. Gold leaf scrap is not that easy to refine. About the only way to refine it is to incinerate it first. However, when incinerating, a large amount of the gold can end up flying away. I recently saw on the internet that one of the bigger leaf manufacturers was offering refining services, but I don't remember which one or where they were located.


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## RustyK (Feb 6, 2018)

Hi Goldsilverpro,

Love the signs, look really nice with the v'd in letters. A lot of work there!!

You're right the waste is about 50%, we manage to get a lot of the loose pure gold swept up and the rest is in 
a mixture of paint of gold size.

I have melted the pure gold quite well. The other scrap is proving harder.

I first let the gold scrap burn, to allow the paint to burn off. I have now tried melting it and have ended up with a black crusts which look like moon rocks!! . I have tried to re melt these and I can see the gold melting but once it cools they go back into the black slag. 

Do you think I could crush this up and try a nitric acid solution ? not sure if this will get rid of the slag.

I will keep trying with this batch. It may be easier just to send it back like you say.
Although they seem to take a very big cut based on the value of our waste cost price.

Aye.


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## nickvc (Feb 7, 2018)

If you have only used flux try boiling it in water, if that doesn’t work add a little sulphuric, be careful sulphuric is nasty stuff, you may need a fair amount of time to remove the flux, fresh water after every couple of hours.
This should hopefully leave just the beads of metal which you can then collect and melt.


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## goldsilverpro (Feb 7, 2018)

RustyK,

Thanks for the compliment.

Are you sandblasting the letters or carving them with chisel and mallet? I always meant to buy a set of stone chisels and try my hand at stone letter carving, but never did. With painted wood, you can repair a minor carving screwup. With stone, you better get the carving right the first time. If you are sandblasting, I assume you are sizing and, maybe, gilding, through the mask.

I fiddled around with leaf scrap a few times, but never found a totally satisfactory method. I'm sure I could have figured out something, had I put more effort into it. I always considered soliciting leaf scrap from other signmakers, but never did. If one could figure out a fast, efficient, safe, cheap method, it could be a good business, Most signmakers keep all their leaf scrap.

Instead of incinerating, you might try a paint stripper, like methylene chloride, but I never liked nasty organic solvents. One time, my partner used standard brake fluid, overnight, to strip 4 or 5 paint layers off of a large metal sign, with one application. Worked great.

I would definitely try nickvc's suggestions, were i you. Of course, experiment with small samples first.


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## RustyK (Feb 7, 2018)

Thanks Nickvc, I will give this a shot. Seems a shame to let it go to waste as I am sure there is quite a bit of value there.

GoldsSilverPro,

We use a mixture of traditional hand cut, leading and sandblast letters. Most of the new stone are sandblast letter for quickness and variety of font style. The older memorials we match in with hand cut letters , quite a work on granite! For bigger letters on granite we usually do them with an air hammer chisel, a lot quicker but heavy on the hands.

with the new memorials we usually undercoat the whole face with a one shot enamel for a couple of coats
then add a gold size and then apply the gold to the letters. We then scrape of the excess and this holds a lot of the excess gold. You are right in that there could be a good business in this type of gold recovery as everyone I know saves their waste also.

You should get a set of good tungsten chisels and give it ago , start with a softer stone like a good sandstone. Natural boulder house signs are becoming quite popular over here also might be worth a go.

All the best
K


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## OBMAD (Nov 17, 2020)

I have managed to remove gold foils from cellphone boards.
However when I used aqua Regia of 55%nitric acid and 32% hydrochloric for rifining the foil. Yes they melted
The problem I faced was I didn't manage to see the gold dust. Its like the SODIUM METABISULPHATE is dissolving for good


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## Shark (Nov 17, 2020)

OBMAD said:


> I have managed to remove gold foils from cellphone boards.
> However when I used aqua Regia of 55%nitric acid and 32% hydrochloric for rifining the foil. Yes they melted
> The problem I faced was I didn't manage to see the gold dust. Its like the *SODIUM METABISULPHATE* is dissolving for good



It should be Sodium Metabisulfite. If you only had a few cell phone boards it is likely there is not enough gold powder to see it very well, if at all.


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## philddreamer (Nov 17, 2020)

What was the approximate weight of the gold foils? This will determine HOW much AR is needed...


> (Hoke states, 4 fl oz HCI (muratic acid) + 1fl oz HNO3 (nitric acid) will dissolve 1 troy oz of gold. This is equivalent to 3.8ml of HCI + 1ml of HNO3 per gm of gold.)



If you used too much nitric, that could be part of your problem! You need to neutralize the excess nitric left in the solution BEFORE you try to drop the gold. And like shark stated, it's sodium METABISULFITE and not METABISULPHATE what you need in order to drop your gold.

Take care!
Phil


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## OBMAD (Nov 17, 2020)

I joined the forum today.
I would like to admit that I had never come across such value and caring people like the ones here on this forum.
Please keep up the good work.
Thanks for the valued advice.
Hence I would go on to ask that how many cellphone boards can I start with again next time to fully accomplish something.
I have been living out of this business of e waste since 2017 and I want to etch and refine on my own at least for this time.
I have great faith with you my newly found family here I will reach my goal.
Together we will make the world a better place
I thank you


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## Shark (Nov 27, 2020)

OBMAD said:


> Hence I would go on to ask that how many cellphone boards can I start with again next time to fully accomplish something.



How many cell phones to show a decent result?

I have no idea as I usually ran them with other boards. I get more cell phones now than I did a few years ago, and I just save them up. One day I will sell them as trying to process them now takes to much space and time that I use to run more profitable materials. I surprised myself in thinking about how long it has been since I processed any boards, it has been over two years!


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## OBMAD (Nov 29, 2020)

Wise words


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## rickbb (Nov 30, 2020)

Cell phone boards should be processed like any other gold plated board. The easiest and lowest cost method I've used is the so called AP process. Use the search feature to find it, discussed quite a lot here.

How many cell board to get a "decent" result, lots and lots and lots. It also depends on how much plating there is, old boards have more plating, new phones very little. 

The plating looks nice but is thin, microscopically thin. So thin it's almost not measurable outside a well equipped laboratory.


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