9kt 40um gold filled?

[sirmaladon]

I have been given some 9kt gold filled chains. each chain is 34 grams, I asked where they got them and i asked the manufacture what the gold filled ratio was, either 1/20 or 1/40. they came back and said the gold filled was 40um thick. each one has 5.5 square inches of surface area, its a rectangular chain. i have been trying to figure the amount of gold in each chain to see if they are worth refining. I tried using the Gold-N-Scrap calculators but i'm unsure if the ratio is 1/50 for gold filled as an option on the website or figure it using the gold plate calculator? Any help would be great, thanks for your time

 

[samuel-a]

sirmaladon

The fact that they gave you the thickness of the gold leaf does not let you know the wight ratio between the gold alloy to base metals, which is the missing variable here.

Using the gold plating calculator is for when 24K gold (or very close to it) is being plated. It will not return true resultes if you input figures which relates to 9K alloy.

 

[goldsilverpro]

I have been given some 9kt gold filled chains. each chain is 34 grams, I asked where they got them and i asked the manufacture what the gold filled ratio was, either 1/20 or 1/40. they came back and said the gold filled was 40um thick. each one has 5.5 square inches of surface area, its a rectangular chain. i have been trying to figure the amount of gold in each chain to see if they are worth refining. I tried using the Gold-N-Scrap calculators but i'm unsure if the ratio is 1/50 for gold filled as an option on the website or figure it using the gold plate calculator? Any help would be great, thanks for your time

I would guess the 9K has a density of about 10.5 g/cc. One micron = .000040". A square inch, 40 micron thick = (.000040)(40) x 1 x 1 = .0016 cubic inches = .0016 x 16.4 = .026 cc. .026cc weighs .026 x 10.5 = .276 grams. It is 9K so the total gold per square inch = 9/24 x .276 = .1 grams.

On 5.5 sq.in., there would be 5.5 x .1 = .55 grams, if my math and your info is right. That's 1.62%. That's about 1/22. The density might be as high as 11.0. That would bring it up to about 1/20

 

[Oz]

Gee GSP, all that math and not even a thank you.

 

[Harold_V]

Gee GSP, all that math and not even a thank you.

Entitlement?

Harold

 

[nickvc]

Personally I would just have processed one, it's not exactly rocket science....
Even a nitric treatment would have provided a good guide as to the gold content but not as quickly as GSPs maths 8)