Craig Martell on sun 27 jun 99
>----------------------------Original message----------------------------
>What exactly is Vee Gum T?? and how is it and the other gum
>materials used?
Hi:
Vee Gum T is produced by R T Vanderbuilt. Offices in Norwalk, Conn. and
Buena Park, Ca. They call it "smectite", which is similar to hectorite
which is also called macaloid,and bentonite. Vee gum and hectorite fire
much whiter than bentonite. They are all forms of montmorillonite which is
a very fine particle size clay with a different lattice structure than
kaolins. Montmorillonites are very plastic gel-like clays that swell a lot
when hydrated and are used as suspenders in glazes and plasticizers in clay
bodies.
I use vee gum t to plasticize the porcelain body that I make thrown ware
from. The guys that mix my body for me put too much vee gum in the last
batch and it really causes some annoying problems. The ware dries more
unevenly due to lack of capillary action, as in water not being passed
freely from drier to damper areas of the pot. I'm getting more shrinkage
from plastic to bone dry. The clay is sticky and it's also much harder to
de-air. They run the clay through an industrial pug which would normally do
a fine job. Before I use the clay I run it through my 4" Venco twice. I
have a high capacity vaccum pump that runs at 95 Kpa, which is 95% of a
perfect vaccum. I still have many small air pockets in the clay even after
kneading well. What's my point? A bit of this stuff is great, but too much
is a royal pain in the butt. AND, any clay supplier is only as good as the
crew they have mixing the clay when it comes to custom mixes, or any other
for that matter. I may have to go back to mixing the body myself. If I
screw it up, fine! I don't wan't to be ticked off at someone else's lack of
attention. I might also add that the normal percentage ofvee gum t that I
use in the clay is 1.5%.
time for some camomile, Craig Martell in Oregon
Craig Martell on sun 27 jun 99
>----------------------------Original message----------------------------
>What exactly is Vee Gum T?? and how is it and the other gum
>materials used?
Hi:
Vee Gum T is produced by R T Vanderbuilt. Offices in Norwalk, Conn. and
Buena Park, Ca. They call it "smectite", which is similar to hectorite
which is also called macaloid,and bentonite. Vee gum and hectorite fire
much whiter than bentonite. They are all forms of montmorillonite which is
a very fine particle size clay with a different lattice structure than
kaolins. Montmorillonites are very plastic gel-like clays that swell a lot
when hydrated and are used as suspenders in glazes and plasticizers in clay
bodies.
I use vee gum t to plasticize the porcelain body that I make thrown ware
from. The guys that mix my body for me put too much vee gum in the last
batch and it really causes some annoying problems. The ware dries more
unevenly due to lack of capillary action, as in water not being passed
freely from drier to damper areas of the pot. I'm getting more shrinkage
from plastic to bone dry. The clay is sticky and it's also much harder to
de-air. They run the clay through an industrial pug which would normally do
a fine job. Before I use the clay I run it through my 4" Venco twice. I
have a high capacity vaccum pump that runs at 95 Kpa, which is 95% of a
perfect vaccum. I still have many small air pockets in the clay even after
kneading well. What's my point? A bit of this stuff is great, but too much
is a royal pain in the butt. AND, any clay supplier is only as good as the
crew they have mixing the clay when it comes to custom mixes, or any other
for that matter. I may have to go back to mixing the body myself. If I
screw it up, fine! I don't wan't to be ticked off at someone else's lack of
attention. I might also add that the normal percentage ofvee gum t that I
use in the clay is 1.5%.
time for some camomile, Craig Martell in Oregon
Robin MacGrogan on mon 28 jun 99
I use VGT to harden my glaze surface before decorating. I tried it in the
glaze batch but didn't care for it. What I now do is put the VGT (mixed
with water) in a spray gun and spray my pots after the glaze has dried. I
let them dry again before doing onglaze work and further over glazing. I've
done this for more than a decade with good results. The glaze surface acts
more like paper than cornstarch. :-) In all these years, I wasn't quite
sure what the stuff is. Thanks to Craig, I now do.
Robin
| |
|
