Using Silver (Ag) as a colorant in a Ceramic Glaze.

admin | Glaze Research | Sunday, May 25th, 2008

In terms of the silver bearing glaze recipe I listed in Clay Times, I do not use Silver Nitrate (AgNO3) any longer. The results were great, but the process involved with using it was ridiculous.

The biggest issue is that it stains and reacts somewhat corrosively with just about everything.
Case in point- don’t use a metal banding wheel (until you’re really ready to get a new metal banding wheel), and if you spray the glaze, wash the gun parts thoroughly.
AgNO3 also alters the pH, thereby severely flocculating the glaze base you’re adding it to.
If you like glazing with “thick pudding”, or having to thin it with so much water that it cracks and peels like desert mud upon drying, then you’ll love silver nitrate!
A parallel problem is that it it doesn’t play well with CMC. AgNO3 knocks the CMC out of solution… and into these neat little gobs of “putty”. Imagine trying to add bits of chewed gum to a glaze and mixing. –It’s as wonderful as it sounds, really.

In terms of Silver Carbonate, Oxide, Chloride, Nitrate, etc –all of it breaks down to that white horse eventually.
At around 400°F, Silver Carbonate (Ag2CO3) turns to Silver Oxide (Ag2O)… then about 125°F later, to Silver powder. During all of this, it releases CO2 and O2 –which is why (little trivia for ya) they use it in space and underwater to “clean/scrub” the air of the carbon dioxide that all the ____nauts and submariners are expelling.

Bill Campbell used straight “Silver Powder” when he played with it… I believe Fara Shimbo used it as well (along with additions of “PMC Clay”, if memory serves).
My concern is how it reacted with the glaze in terms of mixing, application, drying, firing, etc, so I switched away from the nitrate form.
I am currently using Silver Chloride. There may be better, or simply “other” options, but you’ll have to do the math find the equivalent amount to add.
I get my silver from Salt Lake Metals (ask for Rocky if you have technical ?’s).

More than likely you will see very little difference of adding silver to a glaze fired in oxidation, although I have seen crystals grow differently when Ag is added at 4% or higher.  You’ll have to perform a reduction firing to get it to reveal it’s hidden beauty.

Crystalline Glaze Test

Hi-yo, Silver!

2 Comments »

  1. I purchased a small bottle of silver nitrate at the NECCA show from US Pigment…they said to spray it on a raku piece to form silver lust. Not much info.
    I will like to experiment but don’t know how to use it.
    I assume I disolve in water, from another web site, I saw it was 1 gram Silver Nitrate in 50 grams Distilled Water makes a ‘Silver Wash’ for pottery.
    Do I wash the pot before I place in Raku kiln …
    Do I spray pot right after it come out of kiln but before it goes in for reduction
    Or do I spay or wash the pot and then put is back into the raku kiln..andy help would be appreciated…or am I walking on the dark side.
    Kathy Daley

    I currently stay away from Silver Nitrate… see my post on “Using Silver (Ag) as a colorant in a Ceramic Glaze
    ~jesse.

    Comment by Kathy Daley — April 22, 2009 @ 6:39 am

  2. Hi Jesse,

    I love your luster crystals they are so beautiful. Recently I purchased silver oxide to test in crystalline glaze. I usually get good crystals, but the silver creates a yellow glass pool ate the bottom of the piece. It isn’t unattractive but I was expecting different results. If you have any tips or ideas for testing the silver oxide I would really appreciate it.
    Thank you,
    Amy Bryan

    Amy, the only way I’ve used Silver Oxide is by sprinkling some onto the glazed pot before firing. See my post on Silver here: http://jessehull.com/2008/05/25/using-silver-ag-as-a-colorant-in-a-ceramic-glaze/

    Comment by Amy Bryan — March 24, 2012 @ 12:20 pm

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