Gold and silver testing acid

[Yef]

Dear Sir,
Can someone help me for exact formula to make testing acid for gold 18k and 14k.
I tried many times using commercial HNO3 and HCl acids. But in vain.

Thanks in advance.
Yef

 

[nickvc]

I’m fairly sure if you have known pieces you can create your own , I’m fairly certain it’s different strength aqua regia , the lower the oxidizer , nitric , level the more resistance high carat pieces will have, you could even try diluting a standard AR solution to see if that works.

 

[adam mizer]

I had problems figuring out what you guys meant. The formulas are in fluid ounces, not weight ounces. There are 29.6 mL in a fluid ounce. I just copied it off the instructions. Please not that I have never mixed these up. I always used the various pre-mixed solutions that I bought from companies that sell jeweler's supplies. I also see them on eBay. They also have 22KT. They're cheap.

If you can measure mL, milliliters, that would be the easiest. Here are the exact numbers. You can probably round them off. Just measure them as accurately as you can. Fluid ozs. don't convert to mL that evenly.

10KT - 22.2 mL nitric - 7.4 mL distilled water
14KT - 23.7 mL nitric - 5.9 mL distilled water - 10 drops hydrochloric
18KT - 5.9 mL nitric - 5.9mL distilled water - 17.8 mL hydrochloric
Silver - 20 grams potassium dichromate - 22.2 mL nitric - 7.4 ml distilled water

I found this old post from goldsilverpro.

EDIT: should have inserted the link, the 14kt is questionable and was answered as 5ml.
https://goldrefiningforum.com/threads/making-gold-testing-solution.311/#:~:text=When you apply the acid to the streaks

I believe based on Technical or Reagent grade Nitric.

 

[Yef]

I found this old post from goldsilverpro.

EDIT: should have inserted the link, the 14kt is questionable and was answered as 5ml.
https://goldrefiningforum.com/threads/making-gold-testing-solution.311/#:~:text=When you apply the acid to the streaks

I believe based on Technical or Reagent grade Nitric.

Many thanks Adam.

 

[adam mizer]

Your welcome.
Oh.... the basic HCL used here in the USA is 31.45%