Posted by John Britt

Thickened Slip, Trailing Slip, Joining Slip

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Newfoundout Potter said…
Great explanation on defloc! It just hit me that perhaps by deflocculating Mal Davis shino it might stop it from curling and cracking during firing. However I guess calcining some of the clay will work as well, but I never know what change in weight occurs after calcining - so I have to calcine out the correct amount of raw clay and then bisque it and that all takes days. Defloccing could be done right away. Would it work?
November 30, 2012 at 9:01 PM
John Britt said…
Malcolms is probably already deflocculated because of all the soda ash. The clay keeps it workable but you are right ...calcine half the clay. You can make an estimate by looking a LOI (loss on ignition) which is probably 12- 15% on kaolin. so just estimate unless you have done it once and weighted the result.

For Malcolm's I would estimate a 12% loss and then use Glomax (calcined kaolin) or use some you have already bisque fired.
November 30, 2012 at 9:19 PM
Eleanore said…
Thanks for this. What is "brushing medium" and how does it relate to this discussion?
December 1, 2012 at 1:02 PM
Eleanore said…
Thanks for this, John. What is "brushing medium" and how does it relate to this discussion?
December 1, 2012 at 1:03 PM
Liz Gowen said…
Thanks john for us right brained folks the BEST for thinkening and thinning slip. Did it last week for the first time with darvan 7. It is unbelievable....Liz Gowen
December 1, 2012 at 2:27 PM
Newfoundout Potter said…
Thanks John for the calcined kao info. Never thought about the soda ash already deflocing!
December 1, 2012 at 6:32 PM
Anonymous said…
How would darvan 7 work on a clay clogged high school studio sink??
December 12, 2012 at 9:44 AM
John Britt said…
A little late on the sink. Roto Rooter is about it. I remember one place I worked ...they had to bring in a backhoe because the drain went into a big cement junction station about 12" x 12" x 12" which had FILLED up with clay!
December 12, 2012 at 9:50 AM
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