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Panamax

Member Since 17 Apr 2010
Offline Last Active Jul 25 2011 12:36 PM
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Posts I've Made

In Topic: Underglaze And Clear Glaze Chipped Off! Low Fire

04 May 2011 - 01:12 PM


I made a plaster mold of a piece and cast it in a low fire white pouring slip. The pieces were handpainted using Amaco Velvets in the greenware stage. Fired to cone 05, applied a clear glaze and fired to cone 05 for the glaze firing. I made four pieces. Three turned out without any issues. The one had some parts of the paint flake off when I picked it up. I have never had this happened to me and have worked with molds and casting. Any suggestions as to what happened and why only the one had some areas that flaked off? Thanks in advance for any advise![attachment=187:101.JPG]




I don’t recall this ever happening to my ware in 36 years of potting until I had to have some ware ‘emergency’ fired for a show. It never occurred to me that the potters in that studio would pick up ware with oily hands. I always assume that studio rules prevail. The ‘Do Not touch other people’s work’ is always the first on any studio rules list. On the day that I came to pick up my ware I saw that people were allowed to eat in the studio! On the clay forming tables! Near the wheels and near the glazing areas Yikes!! It is so very easy to transmit oils by eating in the studio.

I am sure it was neither the underglazes nor glaze that I used that caused this problem. Only one piece out of 38 had this flaking and on a rim.
Trying to figure out what happened poses a lot of questions. You can use these questions as a diagnostic.

-Was the piece handled by anyone who could have placed natural body oils from their hands or even sweat from their face on the piece? Oils create a resist and affect glaze adherence.
-Did anyone possibly splatter some food, oil or oily liquid or wax on the piece?

Some of the areas on your image looked as if drops had been falling down at an angle.

-Was the piece bisque fired and rinsed prior to glazing with unclean hands?

-Was it possible that some critter walked or flew by and 'stopped' on the piece?
They have oils also.
There are a lot of variables but all we can really do is try to limit contact to our ware and be as clean as we can. Tell family and friends to be extra careful and Do Not touch the ware before it is glaze fired. Keep your ware covered in plastic until ready to be glazed and/or fired.


Thank you! This is possibly what happened. I will be extra careful next time. As with everything, complacency got me.

In Topic: Underglaze And Clear Glaze Chipped Off! Low Fire

28 April 2011 - 09:42 PM

It could be one of the first ones, now that you mention it. But what does the plaster do to the casting slip? Create some kind of barrier to prevent the underglaze from adhering? Interesting.

In Topic: Underglaze And Clear Glaze Chipped Off! Low Fire

28 April 2011 - 09:38 PM

Is it possible it was the first piece you cast and the surface picked up some ? off the mold?


In Topic: Dead Field Mice In My Slip...

05 March 2011 - 12:26 PM

I really don't like mice in the studio nor in the house. I would agree with the long description on hanta virus. It was prevalent in Montana. The advise there was to spray diluted bleach on dusty areas with mouse turds and proceed to clean out the debris. In a slip, I have added diluted bleach to rid paper slip and porcelain slip of stinky black slip.
It works and hasn't caused any problems. I have been using my scrap for slip and experimenting with transfer images by pouring the slip on top of the image created on a plaster bat. No problem from the bleach.

Marcia



How about for a smelly glaze? I have a glaze that has bone ash in it and it stinks..the kids and other students take a smell of that and are disgusted..If I pour diluted bleach, like for the paper slip, will it affect the glaze?

In Topic: Need Help Firing A Manual Kiln

05 March 2011 - 11:58 AM

will you be bisque firing first to 04 or 06, then glaze firing to cone 6?



I will do a single firing to cone 6. I'm leaving the clay body in its natural state.