[Clayart] Cracks and slow seepage- porcelain

ronroy at ca.inter.net ronroy at ca.inter.net
Sun Jul 11 18:00:38 UTC 2021

Hi Madeleine,

The clay is not vitrified enough and water etc. is getting in the clay  
over time. Does the description from Laguna say it's a cone 6 clay or  
does it say it is good over a range of temperatures?

It's not uncommon for clay companies to sell clay that does not  
vitrify enough at the temperatures they specify. That means whats in  
the dish water and food also gets in.

If you microwave one of the suspected pots and it gets hot it means  
there is water in it. Just microwave the empty pot 10 seconds at a  
time for 2 minutes.

I can send instructions on how to actually test the clay to see the  
percent of absorption.

I hope you fire with cones - that is the only way you know you are  
getting to the temperature you want.

Perhaps a call to Laguna would help. I would like to hear their  
explanation for one.


Quoting Madeleine Hall-Arber <arber at mit.edu>:

> For years, I have thrown pots out of Miller/Laguna #16 clay fired to  
> Cone 6 with slow cool, primarily using recipes from Mastering Cone 6  
> Glazes, though occasionally experimenting with other glazes?some  
> from Britt?s compendium.  My daughter uses a variety of my small  
> cups and bowls to prepare her meals in the microwave.  She never  
> puts them in the dishwasher and handles them carefully.  We?ve  
> noticed that several have developed long cracks that we can see  
> (presumably from food stains).  In several cases, the foot of the  
> pot has yellowed.  I?ve also noticed that our soap dispenser  
> accumulates a scummy surface at the foot.  Any ideas?   I tell  
> customers that my work can be used in the microwave (and  
> dishwasher), should I not?
> Thanks for your help and knowledge!
> Madeleine
> Madeleine Hall-Arber
> Madeleine?s Mud Pie Studio
> (617) 510-5955
> Etsy: madmud.etsy.com
> Instagram: madeleinehallarber
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL:  
> <https://lists.clayartworld.com/pipermail/clayart/attachments/20210711/9a81fc30/attachment.htm>

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

More information about the Clayart mailing list