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Bob Coyle

Member Since 06 Jun 2013
Offline Last Active Jul 06 2015 10:33 AM

Posts I've Made

In Topic: Cornish Stone Substitution

27 June 2015 - 08:29 PM


Glaze materials really are cheap no matter what they cost if you think about it.Especially feldspars.
At least that what I have found.

Mark is correct. Just remember that any feldspar you use as a glaze component is a complex mix that might work as well or better with a combination of other (cheaper) materials of approx the same chemical composition.  the ONLY way you can find out is by testing and tweaking. Cornish stone does not have any wonderful, inherent properties that would be impossible to get otherwise.  Software calculations MAY get you closer, but you probably will have to fine tune to get just the results you want. This means understanding how to move the gaze in the direction you want by manipulating the components. There is plenty of info out there and as a newbie it is greatly to your advantage to learn at lest the basics of glaze formulation.


Start out with Min's formulation from Digifire and go for it.

In Topic: Clay Storage Environment

26 June 2015 - 11:51 AM

I have had good luck with storing my clay in closed 20 gal plastic bins. I put a open container of water on the bottom and it keeps the clay from drying out through the plastic.

In Topic: Oxides Affecting Satin Finish?

06 May 2015 - 01:52 PM

I have a nice semi matte (satin) base glaze I use with 0.5 % cobalt carb. When I tried it with  3% copper carb it goes more matte. with 3% RIO it becomes shiny. RIO can be a flux at cone 6 temperatures. Probably the semi matte glazes I formulate are right on the edge anyway. It's a lot harder to get a stable satin than a shiny glaze. If you are on the edge then any additive will probably change the surface texture.

In Topic: Attaching Porcelain To Plexiglass (Adhesive)

22 April 2015 - 08:04 PM

Try roughing up the plexi where it won't show behind the piece. You might even try drilling a few shallow holes at a slight angle.  this will give the epoxy something to bond to.Rough up the back side of the  porcelain also. Epoxy will bond if it has a rough enough substrate. A glass artist here in Santa Fe used 5 min epoxy to  bonds 2" blocks of plexi to ten pound glass pieces and hangs them on the wall. I have done the same with ceramic sculptures.  I leave the area I am gong to bond unglazed, and it works fine.

In Topic: Just Bought My First Kiln... Now What?

22 April 2015 - 07:53 PM

First off... assuming your kiln is electric... was it set up correctly to the power... are you sure? If not, then get an electrician involved.


Start out simple.  All you need is some clay and maybe a rolling pin. Search the internet for ideas. There are a million of them out there. Probably start out with "hand building". this is where to start (unless you got a wheel, which is a whole different set of problems) to see if this is really for you... it might not be.


If I were you I would start out with some low fire white clay. just ask for low fire white. cone 05 or 04. buy two or three pre-made glazes for this temperature. The people at the glaze store will help you. Don't buy too much. no more than a gallon or less. You are going to start by brushing this on, so ask then for the right kind of brush to do this. Ask for a glaze that matures at cone 05 to 04.


If your kiln has a digital controller... you are in luck, you have more control over your firing.. If not, well you need to learn what cones are used for, and what a "kiln sitter" is.

Roll out a slab and make a box or two. Make a pinch pot or two. Get a cookie cutter and cut ceramic cookies out of the clay you role out with your kitchen rolling pin.

Best thing of all... TAKE A BEGINNING CLASS AT YOUR LOCAL J.C. OR CLAY STORE!!! Nothing beats having a teacher. Otherwise you may feel lost.

Start out slow, and don't get discouraged... ceramics has a steeper learning curve than painting or drawing. You are already familiar with art... think 3D! and just have fun.


At this stage Google will be your best friend. The people in this forum love to help. The more specific the question you have, the better the answer will be. Keep us informed how you are doing.