Longtin, Jeff on thu 30 may 02
Dave,
Years ago I learned that barium is added to terra cotta slip cast bodies to
aid in deflocculation. One problem that can be encountered though is that
the soluble salts in the barium can come to the clay surface as the pot is
drying and cause a certain amount of scumming.
The white fuzz on your plaster slabs could be the result of barium in your
clay body?
Probably unlikely but then again...
Take Care
Jeff Longtin
Marni Turkel on fri 31 may 02
Jeff,
You mentioned soluble salts in barium coming "to the clay surface as
the pot is drying and cause a certain amount of scumming". My
understanding of adding barium to slip clay is different. I do notice
an effect as a deflocculant, but the reason I add it to my slip clay
is to counteract soluble salts. If I notice the greenware pieces and
the molds are getting discolored (I assume from migrating salts) and
the seams and cut edges of the ware become harder to clean, I adjust
the barium up until the problem stops. I don't know if it is from
seasonal changes in the well water or batches of dirty clay.
Marni
--
Marni Turkel
Stony Point Ceramic Design
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone: 707-579-5567
Fax: 707-579-1116
http://www.marniturkel.com
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