Enamels and Nitric

In making plique a jour jewels, I prefer 18k gold as my choice of metal. But as you have seen other karats of gold can be use as well as, copper, sterling silver and fine silver. All of which except the pure metals, oxide when firing the enamels in place.

To deal with the oxidation you can deplete sterling silver by using sulfuric acid and nitric acid for gold. I use nitric acid to deplete the 18k gold in most cases before enameling. But once in a while it is necessary to do so after enameling in the technique of plique a jour. I have started a list of the enamels that are not affected by the acid. By the way if there is a B in front of the number it is Bovano.

If you are using enamels that do not take well with acids, deplete the gold first in nitric. I heat the nitric in a beaker just to a slight steam, and dip the heated jewel into it and the oxides dissolve quickly. I usually repeat this until the jewel can be heated in the kiln and produce no oxides.

It very very important to wear protection!! Nitric is dangerous. I work outside and wear acid gloves and goggles and a respirator. Also on the table is a fan blowing the fumes away from myself and the studio.

Colors in Nitric 


A105B         When dipped in nitric acid in a quick bath after enameling it dulls the shine and pits the surface.   When fired the dullness get worse.


B 518  This enamel was deteriorating, so I put a few drops of nitric acid in the 518, rinsed well and tested the firing of, with no effects except it harden the enamel.Which makes it a longer fire.


Ninomiya #N3,  does not work well when washed with Nirtic before enameling.

B 610             Great

N G 338       Great

NG 302       Great

B 209          Great

L 69

H 24

LT 74

LT 71

LT 70

H 55

N 73

N 72

N 71

One thing I figured out this week when using colors that are affected by the acid is to add a layer of Bovano’s # 3 over the color and all is fine.


6 thoughts on “Enamels and Nitric

    1. Patsy Croft Post author

      Nina, this just came through. Sorry to take long to help. I use it straight from the bottle. Wear all proper protection gear!

  1. Giacomo

    Nitric acid is very poissonous , corrosive and hard to obtain, so I am using a weak solution ( 15% ) of Clorhidric acid with water . Works excellent with any yellow gold , especially with 18k , leaving a beautiful mate yellow lemon colour and most of all , not damaging the enamel . And not needing warming , the depletion is fast at room temperature , almost 2-3 minutes , maximum .
    Of course , not good for silver or copper , but the best for yellow gold .

    1. Patsy Croft Post author

      Thank you for the post. I have not explored Clorhidric Acid, but I will. Like you said nitric is dangerous and takes a lot of precaution.


    2. Patsy Croft Post author


      I can not find that here in the US. Is it possible it could be under a different name?



Leave a Reply

Your email address will not be published. Required fields are marked *