Technical Update


I had a customer ask me about some small spots that she had noticed in her clay.

I investigated the problem to see what was going on. What I found is that this is a problem with our raw materials supply. The proof of this is in the two photos above. The top photo is our High Temperature Porcelain for the People Throwing Body and the bottom picture is our Mid Temperature Coup Casting Slip. Unfortunately, there are a few little Red Iron Oxide spots in the bodies. The reason that we know that the problem is in the raw material supply and not our process is because the Clay and the Casting Slip are processed in completely different production lines. They are never touched by the same equipment.

Part of making a clay that is so great to work with is we have to diversify our materials. Most porcelains are made with one clay source. The predominate clay used is very white but not particularly workable. To make our clay workable, we blend that clay with some American Kaolins that help the workability. The problem with American Kaolins is that they are contaminated with Iron Oxide and Titanium, which can cause spotting and tinting of the clay. Sadly there is nothing we can do to fix the problem, as we are at the whim of the quality of our materials.

We have always said that our Porcelains for the People line of clays  are the most worakble, but not the whitest porcelains out there. Unfortunately this is one of those situations. We hope you understand, we want to do the best we can for our customers, but sometimes there are things that are beyond our control.


On another technical note, We have had a few customers ask about having some of their old glazes craze on our bodies.  We understand that this can be a big frustration for those experiencing crazing. Part of making a body that is so rugged in the firing is that the body is not designed like other clays that you may have used. Unfortunately as there are tens of thousands of glazes out there and every glaze fits every clay differently.
To help everyone out, we are working on some glazes that are designed to fit our bodies perfectly.

As you can seen in the picture. this is the clear gloss on Porcelain for the People. This glaze is not just craze free, but it has been put in an autoclave that creates 150psi in a steam atmosphere. If it won't craze under those conditions it won't craze at all.

We just have a little more tweaking to get the glaze as  glossy as possible and check it's qualities on our upcoming Snow White and Stonedware bodies,  and then we will give you the formula. You read that right. We are going to give you the formula. All yours, Mix it, match it, trade it with your friends.  So keep your eyes peeled right here on the blog the formula will be coming at you really soon.

After that, we are also going to give you a Matte Glaze and then onto a Mid Temperature to match The Coup.

So, thanks for all your support, and know that we are doing our best to give you the best ceramic experience out there.



Steve said...

Hi from the UK.
Have you tried running your contaminated porcelain materials in liquid form over a strong magnetic source?
Over here Valentines, our leading Porcelain makers do that to ensure purity.

Ben said...

That will work on the magnetic forms of iron. Some of the oxides are non magnetic and it all depends on what form the iron contaminant is in.

Matthew Katz said...

Ben beat me to the response.
We have tried magnetic filtration and the source is non magnetic. Most of the things that contaminate clay materials are in oxide forms that are non-magnetic (RIO, Mica, etc.)We are currently analyzing our materials and have found some leads.

Jack said...

"Have you tried running your contaminated porcelain materials in liquid form over a strong magnetic source?"

I should hope they do this all the time!

Magnetic treatment is standard practice in the production of whiteware slip, porcelain or otherwise: not to do is very, very flawed practice.