[Ginny C]

Electric kiln, wheel thrown AND hand-built from slabs, slightly arthritic hands....I have loved the feel and ease of Laguna B-mix cone 5 clay, but I HATE the fact that my vases leak just enough to leave terrible marks on wood tables! I know I need a lower absorption rate clay.

I'm not stuck on using a white clay—would actually prefer something that looks more like a reduction fired body. And I like the look BUT I don't like the feel of a rough grog, which hurts the sides of my hands when I'm struggling to center!

Given all those parameters, what clay would you people suggest I order now??
Ginny C.

[justanassembler]

Ginny C, on 01 February 2013 - 12:13 PM, said:

Electric kiln, wheel thrown AND hand-built from slabs, slightly arthritic hands....I have loved the feel and ease of Laguna B-mix cone 5 clay, but I HATE the fact that my vases leak just enough to leave terrible marks on wood tables! I know I need a lower absorption rate clay.

I'm not stuck on using a white clay—would actually prefer something that looks more like a reduction fired body. And I like the look BUT I don't like the feel of a rough grog, which hurts the sides of my hands when I'm struggling to center!

Given all those parameters, what clay would you people suggest I order now??
Ginny C.

I think laguna lists b-mix ^5 as having ~2.3% absorption @ ^5... Are you sure you're firing it hot enough? Have you done any absorption testing on the clay in your firings to see what you're getting? Below is the process I use to test absorption:
Make 6 bars, same size, do not score or indent them, leave them plain on all sides.

Fire to maturity

Take dry weights

Boil bars for 5 hours

Leave to cool in water for 24 Hours

Wipe surface dry

Weigh bars

Saturated weight-dry weight/Dry weight x 100 =absorption percentage
shoot for 1.5-1.8% for cone 6 stoneware

if absorption is acceptable, and crazing still occurs, then start feeding in silica

Move your tests in 5-10 part increments, anything smaller may not show enough difference to make determinations


do some tests that way and see what you're coming up with. If the absorption is @2.3% it seems odd that you'd be having porosity problems like you are.

[weeble]

Laguna makes TWO VERSIONS of B-mix, one matures at cone 5, one at cone 10. Are you sure you've got the correct B-mix for cone 5? I've been using the cone 5 B-mix with grog for years with no seeping problems, but I am VERY careful to get the cone 5 (I often have students make the run to the clay place because its 2 hours away and they're going anyway)

[OffCenter]

Ginny C, on 01 February 2013 - 01:13 PM, said:

Electric kiln, wheel thrown AND hand-built from slabs, slightly arthritic hands....I have loved the feel and ease of Laguna B-mix cone 5 clay, but I HATE the fact that my vases leak just enough to leave terrible marks on wood tables! I know I need a lower absorption rate clay.

I'm not stuck on using a white clay—would actually prefer something that looks more like a reduction fired body. And I like the look BUT I don't like the feel of a rough grog, which hurts the sides of my hands when I'm struggling to center!

Given all those parameters, what clay would you people suggest I order now??
Ginny C.

First of all, I hope you aren't selling those leaking vases. Cone 5 B-mix doesn't leak when fired to cone 5-6. Are you sure you're firing to maturity (cone 6)? Are you sure there is no structural reason for the leaking?

Jim

[Iforgot]

I have never had that problem with b-mix. are you sure it's the clay and not the glaze?

[JBaymore]

Iforgot, on 02 February 2013 - 12:01 PM, said:

I have never had that problem with b-mix. are you sure it's the clay and not the glaze?

If a clay body is actualy approaching full vitrification (0% absorbtion/porosity)...... the glaze being pitted, crazed, crawled or not even there will make no difference in the "weeeping" of the piece. The clay body itself will not "leak".

best,

......................john

[OffCenter]

JBaymore, on 02 February 2013 - 12:33 PM, said:

Iforgot, on 02 February 2013 - 12:01 PM, said:

I have never had that problem with b-mix. are you sure it's the clay and not the glaze?

If a clay body is actualy approaching full vitrification (0% absorbtion/porosity)...... the glaze being pitted, crazed, crawled or not even there will make no difference in the "weeeping" of the piece. The clay body itself will not "leak".

best,

......................john

Plus, all too often people think they can fix a leaking clay with a glaze. Not a good idea since almost every time that will not work.

Jim