How much gold is roughly in a plated watch like this?

[Curiousrefinerg]

Hello, I’m new to gold refining and am currently trying to figure out roughly how much gold is in gold plated Items before I decide whether to refine or sell them.

I know it is a minimal amount but I’ve got stacks of these watches and would love an opinion please + any advice would be greatly appreciated!

Unfortunately I don’t have my scales with me currently but I estimate the watch to weigh about 40g minus the movement.

So far, I’ve built up about 5kg of different plated watch parts but have no idea the value.

Thanks In advance!

If this is the wrong place to post please let me know.

Kind regards,
Curious gold refiner

 

[nickvc]

In honesty unless you are dealing in very large volume and stripping just the gold it’s not really worth the effort , if you get rolled gold / gold filled that’s much better to refine .
If the watches work sell them on eBay, if you get £10 each thats much more than the gold you could recover , and use any money you receive to buy carat scrap which is much easier to refine.

 

[haveagojoe]

Almost impossible to guess as you don't know how thick the plating is or what karat.
You could make a conservative estimate: lets assume the plating thickness is 1 micron (0.001mm); since the watch is a pretty rectangular shape you could measure it and estimate the surface area, multiply by the thickness to get the volume; the density of gold is 19.32g/cm³ so you can figure out the gold weight if it were 24kt, then since there is no hallmark lets say it's only 9kt so multiply by 0.375 to get the final estimate of the weight of gold. This would be very rough but will give you a vague idea. Sadly not as much as it looks, but maybe you get lucky with thicker plating.

 

[Martijn]

My customer fishes in your island pond
These watches have crossed my path several times, but in a batch of very different types together.
If you're buying and processing, sort by type and test, that's what I did A LOT for my customer. Now he knows what to stay away from and what to look for.
This type has some good gold on them, not too thin a layer. You can expect 2 to 4 grams per kilo, that is after stripping the clocks and glass out. The base is pretty solid copper or brass and that makes the weight of the plating layer go down percentage wise.
Clean watches process a lot faster and keep the acid good for a longer time. So degrease!
The stinky human dirty grease keeps the item from making good contact in the cell and then you have small squares that are not stripped.
Heating them can burn off some grease, but can also burn it on your items, making stripping harder.
A paint stripper heat gun can melt aluminum parts, leaching gold plating to make purple alu/gold alloy. > It's a mess.
There is a lot of fake gold plated out there, so watch out. Pun intended.

 

[Martijn]

But first: Welcome! You have a lot to learn. You may receive a recommended list to read, (@Yggdrasil) but I would advise to study the sulfuric stripping cell and "Dealing with waste" first.

Don't do anything without asking and please present your plan first. We can review and correct to save you on expensive or life altering mistakes.
And have fun!

 

[haveagojoe]

The base is pretty solid copper or brass

If so, this could go in Copper Chloride leech, no? Easier and less hazardous than a cell, athough slower...

 

[Martijn]

If so, this could go in Copper Chloride leech, no? Easier and less hazardous than a cell, athough slower...

No. Foils on PCB fingers scream AP, as they have a volume ratio of about 1:1. This already takes a long time. Weight of gold foils compared to copper to dissolve ratio to will be 2:1 roughly.
A watch like this has a gold to base metal weight ratio of 1:250 at best. (4gr/kilo) Meaning it will be 250 times slower than fingers. And use 250 times more HCl.
All chances of profit gone. And a swimming pool full of chemical waste.
Imo.

 

[anarxi]

bite into pieces and pickle in dilute nitric acid.
ratio 1 to 4
body weight to acid weight.
and it needs heating...

 

[Alondro]

This sounds like a job for SUPER SULFURIC STRIPPING CELL!!

Thin plating on thick parts is just what sulfuric acid stripping is for.

Though, if the OP is brand new to chemistry... ehhhh... maybe not.

But, could electrolysis work? Scratch the surfaces a little and electrolyse in acidic copper sulfate solution? It wouldn't get ALL the base metal out before it started to break up, but it would remove a huge percentage of it, making dissolving the remainder more feasible.

 

[haveagojoe]

No. Foils on PCB fingers scream AP, as they have a volume ratio of about 1:1. This already takes a long time. Weight of gold foils compared to copper to dissolve ratio to will be 2:1 roughly.
A watch like this has a gold to base metal weight ratio of 1:250 at best. (4gr/kilo) Meaning it will be 250 times slower than fingers. And use 250 times more HCl.
All chances of profit gone. And a swimming pool full of chemical waste.
Imo.

I don't mean to dissolve the whole thing. Just to release the plating.

I use Copper Chloride for larger gold plated items such as the 90degree SMA coaxial connectors, which I believe have a brass substrate. It works well with an extra shot of peroxide which I don't usually use for fingers-type material. The plating comes of in just a day or two, in large flakes which can be easily separated from the remaining base metal carcasses using a strainer. Once the gold has been released, the carcasses often aquire a slimy grey or black layer of cemented other metals which seems to prevent the rest of the base metal from being attacked. I think in some cases brass is plated with copper first before the gold top layer which is why the gold releases easily.

This approach does tend to make a mess of the Copper Chloride solution due to the other metals in the substrate alloy, so I leach such heavier items in recycled solution which is nearing the end of it's life, and keep the fresher solution to use on cleaner materials. I haven't tried anything as large as a watch but I would surely toss this one into Copper Chloride solution and see what happens.

 

[nickvc]

If you have access to an xrf and all the items are the same try and find out what the base substrate is made of,
If it’s a copper substrate melt and construct a copper cell , if you have stainless then reverse AR will work well , if it’s a mix try and separate into substrate types and we hopefully can give further advice.

 

[Martijn]

I don't mean to dissolve the whole thing. Just to release the plating.

I use Copper Chloride for larger gold plated items such as the 90degree SMA coaxial connectors, which I believe have a brass substrate. It works well with an extra shot of peroxide which I don't usually use for fingers-type material. The plating comes of in just a day or two, in large flakes which can be easily separated from the remaining base metal carcasses using a strainer. Once the gold has been released, the carcasses often aquire a slimy grey or black layer of cemented other metals which seems to prevent the rest of the base metal from being attacked. I think in some cases brass is plated with copper first before the gold top layer which is why the gold releases easily.

This approach does tend to make a mess of the Copper Chloride solution due to the other metals in the substrate alloy, so I leach such heavier items in recycled solution which is nearing the end of it's life, and keep the fresher solution to use on cleaner materials. I haven't tried anything as large as a watch but I would surely toss this one into Copper Chloride solution and see what happens.

If that works on watches, i am not sure, but if the gold is on a layer of something else, like nickel, it might work. I've had pins and more solid pieces where the foils did not release first, and even the last bits of gold were still on copper base leftovers. It was kind of random where the copper was attacked.
You would have to test. And for 5 Kilo it may be doable.

The OP still has to decide if wants to process or sell.

 

[haveagojoe]

If that works on watches, i am not sure, but if the gold is on a layer of something else, like nickel, it might work. I've had pins and more solid pieces where the foils did not release first, and even the last bits of gold were still on copper base leftovers. It was kind of random where the copper was attacked.
You would have to test. And for 5 Kilo it may be doable.

The OP still has to decide if wants to process or sell.

Yes it doesn't always work, certainly not if the gold is plated directly onto stainless steel, as may be the case with watches. But worth experimenting I'd say, as it would be so much easier than a cell. The only issue would be that if it doesn't work, the material would need to be cleaned and dried very thoroughly -perhaps roasted to be sure- before introducing into a sulfuric cell.
If OP decides to process, maybe a very small experiment with a couple of links of the watch band would be the way to go, rather than a whole watch.

 

[Martijn]

Yes it doesn't always work, certainly not if the gold is plated directly onto stainless steel, as may be the case with watches.

Then nitric would be a good option. I toss it all in the concentrated H2SO4 stripping cell.
Some types of stainless do get eaten after a while.