pin holes in only 1 of the 3 clay bodies in kiln?

[clay lover]

Just unloaded a kiln ^6. Every piece with a certain clay, that I use regularly, had tiny pin holes! No matter which of several glazes, or where they were in the kiln. All witness cones correct, all other clays with the same selection of familiar glazes were fine. All pieces were bisqued in the same kiln to the usual temp, 1920*

 

The pin holes pieces were all thrown the same day from the same box of clay.

Any ideas what gives? I haven't a clue what to change.

Of course, I've got a show coming up and glaze firing every day.

[ratdog]

What was ur prep from bisc to glaze.

Dust? Wash? Sand?

[clay lover]

There was no particular prep after the bisque, since I usually unload a bisque , wax and immediately glaze and fire the same day if possible, so things don't sit between bisque and glaze.

This time, however, the dark clay pieces were all boxed between firings as bisque to save shelf space and the flat bowls that pin holed were on a shelf for a week. Could that explain having pinholes on the undersides of the flat bowl rims as well as the upper sides?

Thanks for the thought, I would not have gone there on my own.

[ratdog]

There was no particular prep after the bisque, since I usually unload a bisque , wax and immediately glaze and fire the same day if possible, so things don't sit between bisque and glaze.

This time, however, the dark clay pieces were all boxed between firings as bisque to save shelf space and the flat bowls that pin holed were on a shelf for a week. Could that explain having pinholes on the undersides of the flat bowl rims as well as the upper sides?

Thanks for the thought, I would not have gone there on my own.

Wel when u use dust as an underglaze it can happen

 

I have an old dishwasher waiting for instillation my plan is to wash them on auto with no soap. After which I will place them in a dust free cabinet with very good ventilation and heat lamp.

Once dry then wax an glaze.

 

I have the stuff ready to go but have a problem.

 

It seems the art seen here has turned into money grubbing placenta smearing show boats.

I can contribute a full studio of equipment to a studio with room but they all want top dollar for a 1 foot by one foot space. Lol I could fill that in five min.

 

A shame really but I guess they gata eat to.

 

Any who at the least dust with a compressor blow them puppy's off well .

 

Good luck an I hope it helps.

[neilestrick]

Every clay body is unique, and some will cause things to happen with glazes that others won't. Since it only happened on that one body, I don't think dust or application or anything specific that you did is the problem. It's just a clay-glaze interface issue. You could try a 5 to 10 minute hold at the end of the firing to try and smooth it out.

[ratdog]

Every clay body is unique, and some will cause things to happen with glazes that others won't. Since it only happened on that one body, I don't think dust or application or anything specific that you did is the problem. It's just a clay-glaze interface issue. You could try a 5 to 10 minute hold at the end of the firing to try and smooth it out.

 

Sorry I had assumed u had used it befor with no problems

If u had then something was done different

If nt sorry. Im self thought and learned well from my mistakes.

 

Lol hard road I'm on but bumps are fun.....bouncy bouncy bouncy

 

Lol

[clay lover]

Neil, I have used that clay and with those glazes many times over several years with no problem. I have a 20 minute hold at top temp, then a drop of 500* per hour to 19oo*.

 

The pinholes are also on the undersides of these flat rimmed plates, so I'm puzzled as to how it could be dust.

Will unload another kiln today with that clay, was very careful about dust, so will see what s what this firing. Let you know later today. similar

[neilestrick]

Neil, I have used that clay and with those glazes many times over several years with no problem. I have a 20 minute hold at top temp, then a drop of 500* per hour to 19oo*.

 

The pinholes are also on the undersides of these flat rimmed plates, so I'm puzzled as to how it could be dust.

Will unload another kiln today with that clay, was very careful about dust, so will see what s what this firing. Let you know later today. similar

 

 

My bad. Didn't see that you had used it before. Still say it's not dust. It could have something to do with the fact that the glaze flows (or doesn't flow) differently on that particular surface. If you glazes can handle it, try holding a bit longer. Also make sure that area of the pot is nice and smooth.

[clay lover]

Neil, I have used that clay and with those glazes many times over several years with no problem. I have a 20 minute hold at top temp, then a drop of 500* per hour to 19oo*.

 

The pinholes are also on the undersides of these flat rimmed plates, so I'm puzzled as to how it could be dust.

Will unload another kiln today with that clay, was very careful about dust, so will see what s what this firing. Let you know later today. similar

 

 

My bad. Didn't see that you had used it before. Still say it's not dust. It could have something to do with the fact that the glaze flows (or doesn't flow) differently on that particular surface. If you glazes can handle it, try holding a bit longer. Also make sure that area of the pot is nice and smooth.

 

 

 

Kiln I just unloaded with same clay and glazes looks some better, I increased the peak temp from 2195 to 2200 for ^6, kept the same 20 min hold. Will continue experimenting, the clay is already bisqued, might as well.