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Bob Coyle

Member Since 06 Jun 2013
Offline Last Active Yesterday, 06:35 PM

#56176 More Clay, Wood And Metal Sculptures

Posted by Bob Coyle on 06 April 2014 - 07:57 PM

Yeah Tyler


Wire brushed it and then "tempered" :) the metal pieces  with a propane torch. The metal is attached to the wood behind with a 1/4" elbow and "floats" about a 1/4" in front of the clay piece... Looks a lot more 3D than the picture.

#56160 More Clay, Wood And Metal Sculptures

Posted by Bob Coyle on 06 April 2014 - 03:19 PM

Fired up the old forge and beat and hammered some bar stock into a curve. Attached it so it floats in front of a faux pit fired  micacious clay and wood.



Attached Thumbnails

  • metal1small.jpg

#56159 Hand-Built Baking Pans?

Posted by Bob Coyle on 06 April 2014 - 03:10 PM

I would get a chunk of 2" x 12" from a lumber yard (sometimes they have trim ends that they are throwing away. Cut it 9" x 13" and cut a bevel on all sides. /___\   This forms an inside mold that works great. I use them for my senior center beginning clay class. They release almost as well as plaster if you dust them with corn starch.

#55908 Mystery Chemicals

Posted by Bob Coyle on 01 April 2014 - 06:53 PM

Color might help. If they are white or grey they could be feldspar, frits, or clay. If they are colored they might be pigments.  Try a dropping a little into a few ounces of vinegar on each one. If it fizzes a lot and completely  goes into solution, then it is probably a carbonate of some sort. If not, it could be a frit or a feldspar.


get a piece of of nichrome ( old kiln element wire) or iron wire and dip it in the vinegar solution of the unknown.. put it in the flame of a propane torch. If it burns red you may have lithium or strontium.  If it burns green, you have copper or barium.  Most frits and feldspar's will show a yellow sodium color. potassium feldspar might show violet tones but might be obscured by the much stronger yellow sodium color.


Then follow Neils advice.


Also hope like hell that you don't use these unknowns and come up with a glaze that is a total knockout... you may not ever be able to reproduce it after you run out of whatever you used to make it.

#54899 Foil Saggar Results

Posted by Bob Coyle on 17 March 2014 - 05:32 PM

Wow Marcia! I'm impressed. That's a lot of torch firing. Maybe you need to graduate to a weed burner. :)

#54577 Vintage Materials

Posted by Bob Coyle on 13 March 2014 - 01:52 PM

Ruth... Those materials are pretty old...you better check the expiration date on the packages... they may not be good anymore :rolleyes:

#54494 Glaze Test Ga28-A Green Breaking Blue

Posted by Bob Coyle on 12 March 2014 - 10:38 AM



Interesting adjustment you made there by substituting additional Gerstley for the spodumene. You effectively changed out the lithium flux (from the spod) for twice the boron (from the additional Gerstley).

That is correct Dick. I didn't have any spod at the time and tried an adjustment with Li Carb and upping the ball clay. I had a ton of G borate so I tried that as a flux  instead and it worked out OK. I added extra TiO2 to opaque it more.


I am trying for a more antique look and the roughness is fine. Firing at cone 6 will smooth out the bumps but produces more gloss with some loss of the green break. The green break also depends on the clay body. Works on darker stoneware bodies.

#53471 Paint Brushes

Posted by Bob Coyle on 26 February 2014 - 11:09 AM

I have made my own brushes from squirrel tail. No I did not kill the poor things but I did fish a couple of dead squirrels out of my rain barrel and cut off their tails. The long, absorbent, fibers from the end of the tail make a great brush for striping and trailing.


I gave the rest of the tail to a friend who ties fly's.

#52890 Test Of Turquoise Matte Glaze

Posted by Bob Coyle on 19 February 2014 - 01:29 PM

The tree was incised in the leather hard pot then it was bisqued. I masked the tree and glazed and fired the pot. Then I electroformed copper into the incised tree and patinated it.

#52844 Test Tiles - How Creative Do You Get?

Posted by Bob Coyle on 18 February 2014 - 08:02 PM

I always paint a horizontal line with black slit on the test tile before I glaze it and then paint another line at a 30 degree angle on the top after I glaze it. This allows me to see how transparent the glaze  is and also to see how much it sags when fired.

Attached Thumbnails

  • test1.jpg

#52817 Test Of Turquoise Matte Glaze

Posted by Bob Coyle on 18 February 2014 - 12:35 PM

Here are some photos of test tiles I made using a recipe taken from the October issue of Ceramics monthly. It makes a pretty nice waxy magnesium matte. It is stable between cone 5 and cone 6 and holds well without sagging with good leveling on the pot. This is important to me because I brush on all my glazes.


This was a straight up run with a shutoff at cone 5 with a kiln setter. the last part of the ramp up to shutoff was 125 F/hr from about 1700F.


The glaze was used on the tree pot which is speckled buff.


Glaze Composition
Ingredient Parts
Frit 3134                       23.40
Flint                              19.80
EPK                             19.10
Custer feldspar (K2O)   14.90
Talc                              11.70
Whiting                         11.10


Cobalt carbonate            0.50
Chrome oxide                0.50
Taken from CM Oct 2000

Attached Thumbnails

  • test1c.jpg
  • treepot.jpg

#51660 Suspenders/binders In Speedball Glazes?

Posted by Bob Coyle on 03 February 2014 - 03:18 PM


To make your own glazes brush well, first add 2% Vee-Gum T to the mix. You need to blunge this well with water before adding it.

One trick I have learned that helps get gums into suspension is to add alcohol at about three times the weight of the gum and let it sit a minute, then add water and stir. The alcohol helps the gum solublize much more quickly and without the clumping you usually get. It also might hold down the bacterial growtrh a little.

#51658 Re Firing Bisc

Posted by Bob Coyle on 03 February 2014 - 03:06 PM

Take a pot out and tap the rim with your finger nail. if it rings, it is bisqued enough to glaze.

#50924 Photography Isn't Just Pressing A Button

Posted by Bob Coyle on 24 January 2014 - 07:50 PM

I'm not sure you can get "professional" like photos without maybe spending a little money on setup and a little time and experimentation how to use it.

#50154 Cristobalite, Please Teach Me

Posted by Bob Coyle on 13 January 2014 - 09:15 PM


Norm, I kind of inherited the bag from my grandfather the rockhounder who got it from a mine in Lompoc, CA.

Are you sure it is not Diatomaceous earth? That is what Lompoc is known for.