Properties of Clay - Physical characteristics: Video #27 of the Free online glaze course

This is a 30 minute video about the physical properties of clay. This is a prelude to building your own clay body or finding clay in the environment (a.k.a. Wild Clay) and knowing what to do with it.

[@kathwheeling]

Heard you mention "Clay" Sunday. ordered it while still in class. Came today. Diving in!!

[@johnbrittpottery]

Great book

[@thatoldbiddy2]

Thanks for another great video John! This was very interesting. I know I'll end up watching this a few times! thanks again.

[@xboxbreadbox8404]

love clay. big clay fan

[@kevinh5024]

These videos you make area awesome. Thanks for posting.

[@potteryincentralwa8449]

I just got your book on cone ten glaze -- good stuff

[@hartgas10]

hi john, thanks for your fantastic video's and making the chemistry accesible. i have a question for you. at my studio in the netherlands we use a lot of different cmmercial european clays....whites. greys. reds and porcelain... individually they all are fired to cone 7 and work just fine, we collected all the trimmings from these works and regenerated the clay...although it felt bit short it was pleasant to work with. now when we fired these works we had a horrible meltdown ..could this be some kind of eutectic unhappy accident and mismatch.... can you shed some light here...greetings from europe

[@johnbrittpottery]

Could be, but usually it is some low fire that got mixed in? Could that have happened?

[@JessicaStLouis-qh6pp]

Hi John, thanks for all the information! I really appreciate it. I'm hoping you can help me out on verification a bit more. I've heard no clay, regardless of body, is really vitrified unless it's got an absorption under 1%, maybe under 0.5%. Apparently this is how verification is defined in the atsm manual. I believe the concern is related to food or dinnerware safety. Have you found any evidence to support or refute this extreme level of vitrification? Thanks!!

[@johnbrittpottery]

Probably "technically" true but stoneware are effectively vitrified at 1-2 %. They are millions of them in use at that level and they are safe to use. If that were true the only clat you could use for dinnerware would be porcelain...just not true.

[@JessicaStLouis-qh6pp]

@@johnbrittpottery thank you!!

[@crunchybeen4263]

Is there a link for this information?

[@johnbrittpottery]

No, that is the video.