# Gold plated brass worth it or not



## Peg leg (Nov 24, 2010)

I have a few pounds of gold plated brass ferrules and I have a couple of questions. Which method would you recommend to recover it and is it even worth it.


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## Peg leg (Nov 24, 2010)

I checked out the specs on the ferrules. The plating is listed as 10-25 micro inches thick and the ferrules are about a inch long and .125 inches in diameter. I was thinking of machining off the playing and catching the chips and then putting them in nitric to dissolve the brass.


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## goldsilverpro (Nov 24, 2010)

Use this formula to calculate the value per square inch of plated area. 10 to 25 micro inches would be .000010" to .000025" in the formula. This figures from $0.14 to $0.35 per square inch. Do the surface area calculations. From this, you should be able to make your own decision. I'm also giving a formula for silver.

For Gold: (plating thickness in inches) x 10.18 x spot price = $ value/square inch
For silver: (plating thickness in inches) x 5.53 x spot price = $ value/square inch


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## metatp (Nov 24, 2010)

goldsilverpro said:


> Use this formula to calculate the value per square inch of plated area. 10 to 25 micro inches would be .000010" to .000025" in the formula. This figures from $0.14 to $0.35 per square inch. Do the surface area calculations. From this, you should be able to make your own decision. I'm also giving a formula for silver.
> 
> For Gold: (plating thickness in inches) x 10.18 x spot price = $ value/square inch
> For silver: (plating thickness in inches) x 5.53 x spot price = $ value/square inch


GSP,
Where does the 10.18 and 5.53 come from?

Thanks,
Tom


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## goldsilverpro (Nov 24, 2010)

10.18 is the number of tr.oz. of pure gold in a cubic in. For silver it is 5.53 tr.oz./cu.in.
.


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## metatp (Nov 24, 2010)

goldsilverpro said:


> 10.18 is the number of tr.oz. of pure gold in a cubic in. For silver it is 5.53 tr.oz./cu.in.
> .


Thanks.


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## butcher (Nov 25, 2010)

speaking of number's, was reading this morning and something dawned on me.
I alway's thought the mole in chemistry was so small, seemed so small to me.
when I used the mole to calculate the amount of a chemical we need in the formula.
but then when you think that:
1 gram of gold = 0.005077 mole
or that:
1 mole of gold = 196.96654 grams :!: :!: 
that little mole does not seem so small.


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## EDI Refining (Nov 25, 2010)

goldsilverpro said:


> Use this formula to calculate the value per square inch of plated area. 10 to 25 micro inches would be .000010" to .000025" in the formula. This figures from $0.14 to $0.35 per square inch. Do the surface area calculations. From this, you should be able to make your own decision. I'm also giving a formula for silver.
> 
> For Gold: (plating thickness in inches) x 10.18 x spot price = $ value/square inch
> For silver: (plating thickness in inches) x 5.53 x spot price = $ value/square inch



Hey Chris

Hope all is well, 2 things

Do you have any equipment for refining / assay available for sale? Not looking for anything specific, just looking for possible deal.

2nd thing: Do you have a rough average yeild on costume gold jewellery ? ppm or g/t type analysis numbers ?


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## lazersteve (Nov 26, 2010)

butcher said:


> speaking of number's, was reading this morning and something dawned on me.
> I always thought the mole in chemistry was so small, seemed so small to me.
> when I used the mole to calculate the amount of a chemical we need in the formula.
> but then when you think that:
> ...



A mole represents a definite number of atoms of an element or compound. It comes from Avogadro's number 6.022 x 10E23. So there are 6.022 x 10E23 atoms of gold in 196.96654 grams of gold. With this many atoms present it is easy to see why there is no such thing as truly 100% pure gold encountered in refining and hence the 9's scales usage. Even with pristeen reaction conditions it's nearly impossible to prevent 1 atom of *any form* of contamination in 602,200,000,000,000,000,000,000 atoms from being present in a 197 g sample of refined gold.

Steve


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## goldsilverpro (Nov 26, 2010)

P3M said:


> Hey Chris
> 
> Hope all is well, 2 things
> 
> ...



I have no refining equipment and, at the present time, my assay equipment has been promised to someone else. If that falls through, I'll let you know.

I haven't really run much costume jewelry. Most of what I worked with was electronics and most was manufacturing scrap. I do remember cyanide stripping 2, 30 gallon drums of gold plated cheap Swank men's jewelry from a manufacturing facility, but it's been too long to remember the numbers. I do have a good grasp of the typical plating thicknesses used for various applications, however, since I once worked for a major plating solution vendor and was very involved with what the users of these solutions were doing.

Although they are only estimates which can sometimes produce errors, I relied on 2 field tests in lieu of a proper assay. First is the number of strokes it takes to penetrate through the gold plating, using a pencil eraser. I realize that there are many variables involved with this, such as pressure, eraser type, and whether the gold is soft or hard. At one time, I did quite a study of this and collected eraser stroke data (which is long gone) based on such things as recovery figures and known gold thicknesses and I actually got pretty good at it, believe it or not. The second way is to weigh some material, measure (I prefer calipers) and calculate the plated surface area, estimate the typical gold thickness on that particular type of material, and, from all this, estimate the value per pound. And, since I was usually on the buying end, I kept my estimates on the low end on the scale.

Costume jewelry is quite often plated with what are called "color gold" solutions. Most of the small bottles of solutions used by jewelers and the brush plating solutions used to plate automobile ornaments fall into this category. These are typically solutions with low gold content (about 0.1 tr.oz./gallon - 0.82 g/l) and the parts are only plated for about 45 seconds, or less, at about 6 volts. With these, the plater is only interested in plating long enough to achieve the proper "color", rather than a particular thickness. As a result, the gold thickness is usually not less than 4 millionths of an inch nor more than 8 or 10 millionths. If the plater tries to plate thicker, the plating appearance will deteriorate. Therefore, the thickness is limited with these solutions. It is possible to plate 45 seconds, pull the part out, put it back in for another 45 seconds, but this is rarely done. There are quality pieces that are 100 millionths thick, but these are rare and are most always stamped with markings such as HGE (heavy gold electroplate - usually with a karat marking also) or Karatclad. Also, most vermeil (gold plated sterling silver) is plated with 100 to 120 millionths of an inch of gold, of at least 10K purity. These thicker gold layers are plated with solutions of much higher gold content - usually 1.0 tr.oz./gallon.

For all you readers, just remember - there are exceptions to EVERYTHING in this business! I learned this the hard way and have had many surprises, both pleasant and unpleasant. Please note that I rarely use absolute terms in my writings. I most always use such words as: often, usually, about, typically, normally, estimate, etc. I use the same sort of thinking when I evaluate material. Think low as a buyer and think high as a seller. Thinking in absolute values will tend to bite you on the butt.


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## EDI Refining (Nov 26, 2010)

Chris - 

I had meant to PM you with those questions. 
Regardless thanks for the reply, happy all the forum readers got a share the information

thank you


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## 10wt_Percent (Dec 12, 2014)

if you have a quantity of identical (identically-plated) parts one could consider weighing a sample of say ten such items and then stripping the plating (off) and re-weighing the stripped (and dried) sample-set. The difference in weight -- divided by the sample size i.e. "normalizing" the data -- will give you (will yield) the weight (of plating) per unit article. 

Sounds about right?


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## blk03001 (Dec 12, 2014)

10wt_Percent said:


> if you have a quantity of identical (identically-plated) parts one could consider weighing a sample of say ten such items and then stripping the plating (off) and re-weighing the stripped (and dried) sample-set. The difference in weight -- divided by the sample size i.e. "normalizing" the data -- will give you (will yield) the weight (of plating) per unit article.
> 
> Sounds about right?



My first thought is that when dealing with plated materials you are dealing with very small layers of precious metals. With gold being so soft, it can often times be "rubbed off." This would lead to variations in thickness even on similar items due to different wear.

Just my thoughts though.


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## necromancer (Dec 12, 2014)

don't use nitric on brass. makes for a messy mess :!:


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## goldsilverpro (Dec 12, 2014)

10wt_Percent said:


> if you have a quantity of identical (identically-plated) parts one could consider weighing a sample of say ten such items and then stripping the plating (off) and re-weighing the stripped (and dried) sample-set. The difference in weight -- divided by the sample size i.e. "normalizing" the data -- will give you (will yield) the weight (of plating) per unit article.
> 
> Sounds about right?


In theory, it is right. Practically, though, it would be quite difficult to get accuracy.

(1) Gold is not easy to strip. With most all methods, some of the base metals will dissolve along with the gold. If you do dissolve even a small amount of base metals your gold answer will be too high and that would be very undesirable. The only exception I can think of is a commercial cyanide gold stripper that includes other proprietary chemicals to prevent attack on copper and other base metals. An example is Technistrip Au, made by Technic. 
(2) A square inch (quite a bit) of 30 micro" gold (fairly heavy gold) only weighs about .0094g.


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## kurtak (Dec 13, 2014)

necromancer said:


> don't use nitric on brass. makes for a messy mess :!:



necromancer

If you are talking about stannic tin (the white tin paste we all hate) then this should not be much of a problem at all with brass as brass is primarily a copper zinc alloy (with only traces of tin) both of which dissolve in nitric 

Bronze on the other hand is an alloy that is primarily made up of copper & tin - in which case yes then you get "a lot" of stannic tin which yes can be messy

However you can deal with getting rid of the stannic tin by incinerating the foils to turn the stannic tin to tin oxide & then rid the tin oxide with hot HCl washes

Kurt

Edit to say; - I have done many, many pounds of brass pins with nitric (I get my nitric really cheap) with out any real issue (mess) bronze are the problem ones so always test a couple grams of any particular type pin with nitric first to determine if they are brass or bronze if you intend to use nitric --- if you get "a lot" of stannic tin they are bronze & you then may want to consider another method (AP or stripping cell etc.)


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