[Clayart] the natural progression

ronroy at ca.inter.net ronroy at ca.inter.net
Tue Nov 8 10:19:37 EST 2016

It's easy to find out if clay is vitrified enough to hold water. Make  
a cylinder about 4 inches high and 3 inches wide - fire to glaze  
firing temperature but don't glaze it. Fill with water and leave on  
paper for 24 hours. If the paper is wet or wrinkled then it's leaking  
and not vitrified.

Fired clay that has absorbed water will heat up in a microwave oven -  
because microwaves heat water! Some ware will get so hot it will burn  
the user. If your clay is not properly vitrified mark it NOT MICROWAVE  

Glazes craze because they contract more on cooling than the clay -  
sometimes it take a while - maybe even weeks - but the cause is the  
difference in contraction during cooling. Freezing continues the  
cooling and therefore the difference in contraction so that should  
show up crazing that is going to happen.

Any ware that is going to be used in the kitchen should be able to  
pass the freezing test and have hot water poured in to it while still  

Better for everyone if we do it right!

Many glazes can be adjusted so they don't craze and the other extreem  
when they break pots. I can do that.


Quoting mel jacobson <melpots2 at visi.com>:

> and, others please join in on the philosophical discussion.
> if you are going to start a pottery, studio, space...it just seems  
> to me that one should start the process with a fine clay body that  
> fits your work.  it is the standard for making your work.  the bones  
> and guts.
> if you are buying ready made, make sure you know the parameters of  
> the body.  what does it do?  crack, warp, or is it perfect for your  
> work.???? that is the first quest.'
> what is the color fired?  when that happens, and you have discovered  
> perfection., you start full production.  and that production will  
> match your kiln and its parameters.
> if that final tally is cone 3, then so be it. if it is cone 7, so be  
> it.  you know you have perfect melted clay.
> the last thing that happens is the finding and matching a glaze that  
> will vitrify and complete the work.  if that is cone 8, who cares,  
> the glaze can be made to match.
> you don't care if it is not cone 6 on the nuts.  it is in a range.    
> you tweak to perfection.
> color, texture all will come with time.  but, you should have  a  
> base glaze that works all the time.  one base that you trust and can  
> pretty much color at will.
> then, i would send all that research to ron roy and say.
> `is this going to work for my entire life?`  pay him to do this.  it  
> is not charity.  it is an investment in your life ,  perhaps the  
> most important step in the process.
> i did not have a hooozah moment one day and say...i fire to cone 11.  
>  just opposite, i did not like cone 9.  it was weak.
> i found the sweet spot for my pots and what i do..it was cone 11.   
> that is what made my work sing. it was thousands of pots to get to  
> that point.
> there is not nobility in firing to cone 11-12.  it just happen to  
> work for me. i love melted clay and glaze. it is my aesthetic.
> period.  each finds their own way.
> but it takes knowledge of materials, a great deal of testing and  
> that includes the final product.
> mel

Ron Roy
ronroy at ca.inter.net
Web page ronroy.net

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