SILVER NITRATE

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This is a glorious glaze which needs patience and practice. With age it gets a lavender  luminescence.

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The crows were waxed on to the bisque before glazing. The smoke articulates the shapes.

This is an example of Silver Nitrate over White Crackle. The interior is a commercial glaze by Mayco. Design info below.

SILVER NITRATE  is the most challenging glaze posted yet. To achieve a gold luminescent glaze is completely worth it. There are things you need to know in advance.
Silver Nitrate can be purchased in crystal form at a pharmacy or chemical company. When dissolved in distilled water (yup, not tap water) it can stain your hands, clothes, tools,surfaces...everything a deep liver coloured purple. 
Historically is was used medicinally, in photography and mirror making. 
Weigh, mix and add to the glaze base outside. Store the extra liquid solution in a brown bottle. Wear clothes that are already stained, wear rubber gloves, and mix with tools that will be purple afterwards. Designate brushes only for this solution.
It doesn't get better....
The nitrate in a glaze solution fires to a very, very soft surface finish. The atoms in the molecular structure are unstable like a Mickey Mouse head that one ear can fall off. But not always. Still with me???
I prepared the post firing buckets like this every time for silver nitrate glaze:
make a substantial cushion of crumpled paper in the bottom of the bucket; place a piece of clean cardboard over it as a stable platform; line the bucket with paper , covering the metal but not falling on to the cardboard. If pieces are small 2 can go into one bucket but they cannot touch or fall against each other. Why? Because the glaze is viscous and the pieces will stick together. As it is,the base of your piece may have the cardboard impression.
Because the atoms are unstable the piece cannot be washed afterwards. When completely cool, gently brush off the ash and hope the glaze stays put. It becomes more stable over time.
Needless to say the pieces cannot be used for anything except contemplation.
2 glaze formulas follow:

SILVER NITRATE GLAZE 1,My favourite. (see top picture)

Gerstley Borate 75
Neph Sye.   20
EPK    5

silver nitrate weighed ,,,,,10 mls. 
dissolve in distilled water. if you mix more than you need store in a brown bottle.

Mix the glaze first, sieve twice then add the dissolved nitrate. It will curdle the glaze so just keep mixing until it smooths out. If you're using wood it will turn purple forever.
Apply 3 coats with a large hake brush that will only be used for this purpose. Dry completely and fire to 1800F. Let cool completely in the bucket then gently brush off the ash. If you wash it the glaze may wipe off,

GLAZE #2
Frit 3110  50
Gerstley Borate   20
EPK      8
Neph. Sye.   22
Tin oxide   2
Rutile    2
Yellow ochre  2
Silver Nitrate   7mls 

Mix and apply as above.

Design technique on the third picture.
1. draw and wax out a design on the exterior of your bisque
2. apply 3 coats of white crackle over the exterior of the bowl. If it sticks to the design, clean off with a small damp sponge. Fire to 1750F and let cool in kiln (not raku-ing yet).
3. With a wide brush apply 3 coats of Silver nitrate over the outside of the bowl.
4. Apply 3 coats of a commercial glaze on the inside. I used a Mayco blue.
Fire to 1800F.
The design will be in a pure nitrate  and the white crackle will have a soft gold sheen.
Brush off the ash.
Some have added 1% BISMUTH subnitrate FOR A LAVENDER EFFECT. But honestly it's not worth it as the silver nitrate becomes more 'lavender' over time.

I'm sure you know this but only display raku out of direct sunlight or spot lights. Clean with a soft cloth sprayed with Pledge. These glazes are not food-safe, and bowls don't like gases given off by fruit! 
 


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