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Bob Coyle

Member Since 06 Jun 2013
Offline Last Active Today, 06:46 PM

Posts I've Made

In Topic: How Much Do You Stay Within Glaze Limits?

Today, 06:46 PM

I have pretty much given up on trying to use limits. For one thing, they are all over the map, depending on whose limit formula you use. In the second place, my experience has been that the real ingredients you use to conform to a limit, cause wide variations in glaze fit and texture.. even though they are almost identical as far as oxide composition is concerned. as John says, The only real way to get what you are looking for is to know a little glaze chemistry and  keep experimenting till you zero in on these characteristics.

In Topic: Input On These Cups/handles

19 November 2014 - 02:30 PM

The first one gets my vote, but I agree with Bezine... the handle could be a little less heavy.

In Topic: Input Would Be Great!

17 November 2014 - 08:38 PM



I also like the look of Rebekah's forms. To me, this is how a beer stein/mug should look. I threw several similar forms for the prototypes I put out. Some people liked these (the more classic look) and some like the obvious " hand built" look which kind of surprised me. So I will do both for the up coming beer fest.


The manganese glaze/slip on the handle is one I poster here a while ago. I got a lot of comments that said it was not "food safe". which may be true, but I usually don't make stuff people eat  or drink from. I think it is fine for a handle though. I fire to cone 5-6 and I have made sculptures with this stuff that were copper plated for four days in a copper sulfate /sulfuric acid solution and the glaze  didn't look like it was effected so it won't come off in the dish washer.

below is the formula is you want to try it.


Ingredient                  Parts
Rutile                       27.00
Red iron oxide          26.00
Manganese dioxide   20.00
Ball clay                   10.00
Flint                           8.00
Frit 3134                    6.00
Copper carbonate       4.00

In Topic: Input Would Be Great!

17 November 2014 - 04:39 PM

Nice classic looking beer mugs. I am making some mugs for a local brew fest we are having here in Santa Fe. I tried cobalt blue on  one of the mugs but is just didn't look quite "beery" enough. I am doing the rest in a kind of matte green and the prototypes look more in keeping with the occasion.  I put it on and partially wiped it to give it a sort of antique look.


I also tried a "twist handle" on one of the prototypes and will probably go with this for the production. I used a matte manganese glaze on the handle that gave it the look of black iron. I will  go with this also since the people I showed it to really liked the effect.


I have attached a photo of the prototype. It is just a hand built "quickie". I was going  to throw the rest of the mugs, but the people I showed it to liked the obvious "home made" look and so I will do some of each. I also stamped  text into the sides of some of them which got a laugh. 


Anyway, the handle got the biggest raves because it looked like a forged metal handle.



In Topic: V Gum Cer In Clay Body

06 November 2014 - 03:03 PM

CMC is fine in glazes but not whole clay bodies. It is expensive and will burn out at low temperature forming CO2... not a good thing to be gassing out of a clay body. If you want to modify the rheology of the clay, stick with the inorganic additives.