Why Whiting Works

[Pamela Theis]

I asked Richard Burkett to explain to me a technical explanation for why/how
whiting functions when added to the salt/soda mixture. This was his response:

Whiting when heated high enough (I can get the exact temp) turns into
calcium oxide (losing CO2) which is really quite refractory (again I
can get the melting point later) IF there's no handy silica or other
material around with which it will form a eutectic. Sodium doesn't do
it, so the sodium (soda ash, soda bicarb) evaporates forming the glaze
while the calcium oxide just sits there waiting to be swept out of the
kiln later. Calcium oxide is not that stable around moisture, so it
will gradually absorb water from the air.

I found this interesting and thought I would share it with everyone.
Pamela

[Keith Phillips]

They work good, although last time I dissolved the soda in hot water and then mixed with whiting, and the burrittos "set". It still worked great but they seemed to take longer to dissapate. I'll go back to cold water next time. Thanks for sharing your recipe!

[Michael Kline]

One thought is that alumina is really expensive. But I don't have any comparison in price to whiting. I'll have to check the catalogs...

[bryce brisco]

here at southern pottery alumina hydrate (at the pound rate) goes for $ 2.15, while cal carb goes for $1.00...

[June Perry - Shambhala Pottery]

Gail Nichols who got her PHD based on her soda work and her discovery of the whiting/soda/water mixture technique, says that the whiting once mixed with the soda and water creates chemically combined water which is released as fumes. The whiting also protects the kiln floor.
The process is a way to get the needed moisture along with the soda to get it to migrate through the kiln without resorting to spraying.
Before my last firing I couldn't do my normal spraying. My hip was totally gone (I've since had a full hip replacement and am at the end of my recovery period), and I couldn't walk around the kiln spraying as I would usually do, so I just made a paste of soda and water and a bit of salt (about 3lbs soda ash, 1lb salt), which I spread on scrap piece of wood and just threw those into the kiln. My kiln has a special firebox for that purpose.
The one pound of salt definitely helped but the volatility of the burning wood and moisture in it as well as the moisture in the paste helped carry the the soda through the kiln. Next firing I'll make the paste again but this time I'll omit the salt and use her whiting/soda/water mixture and spread it on the wood.

[Emily Murphy]

The ease of using a dry (as opposed to spray) mixture is one of the main reasons why I switched from spraying. It's much easier to do solo (and safer). I also have students adding the soda to the kiln on a weekly basis- most of whom have no previous kiln experience. It's much more comfortable for them.
Using a piece of wood to add it is an interesting idea. It would resolve the issue of the soda mixture sticking to the angle iron if you're not fast enough. I'll have to give that a try!

[June Perry - Shambhala Pottery]

I didn't use any whiting - just mixed up the soda with water to a pretty wet paste consistency, spread it thickly on the wood pieces. The wood also has some water in it which I think probably helps as well in migrating the soda through the kiln.
Without the whiting in it, it may still deposit the soda on the kiln floor, but my high alumina kiln wash might help. If not, I can add the whiting.
My first attempt at making the Nichols mixture is that it didn't harden, so there went that experiment. A few days later it was like a rock, so I guess I could break it up and use it now.
I know the whiting/soda mix doesn't harden with all soda ash. Since then I've gotten a bag of the recommended one.
The wood serves other purposes for me - one of which is bringing up the temperature in bottom of my kiln. It also give me good reduction for my celadon and shino liners.

Regards,
June

[Emily Murphy]

A note about soda ash:
I took a workshop with Gail Nichols several years ago. She explained that when she was home in Australia, her whiting, soda ash & soda bicarb mix would solidify into nice chunks with water. But when she traveled to the US for workshops, her mix wouldn't harden. It turns out that the soda ash is different here. To get the equivalency of Australian soda ash in the US there are 2 options. 1). Buy soda ash that is referred to as "light soda ash." or 2). Calcine regular soda ash. I have calcined the soda ash before (just by putting some in a bisqued bowl in a bisque firing) and use it and that does the trick. But at the time I was firing too regularly (1 - 2 time / wk.) between firing student's work and my own. It was too difficult to keep up with having enough calcined soda ash on hand. That's when I started playing with alternative methods and ended up mixing the same basic mix with wood chips and scooping it onto an angle iron.

[June Perry - Shambhala Pottery]

The last bag of soda ash I bought at Highwater says "Light soda ash", so it would probably work with her method.
I'm assuming that the whiting soda ash you're currently using isn't hardening like the light soda ash, which is what happened to me.
Do you find that the whiting, even though it's not hardening with regular soda ash is still protecting the floor of the kiln used with the wood chips?

June

[Emily Murphy]

It's totally protecting in the same way. At the end of the firing, the chunky mix that's left in the fire box will break down in a couple of days. Or if I want to speed up the process, I "sprinkle" water over it and it will be broken down in a couple of hours. I usually clean out the box really well, but you could do a half-hearted job and leave some of the remaining powdered whiting in the box to help protect the firing box for the next firing. Or what I do is to clean it out really well, and then dust the floor of the fire box with new whiting.

[June Perry - Shambhala Pottery]

That's a good tip on sprinkling the water to accelerate the break down of the whiting, particularly if you have a fast turn around firing.
Do you have a copy of Gail's new book? It's a wonderful source of soda firing information - a real treasure.

[Emily Murphy]

I do have her book and love it!