Annabelle on sat 5 may 01
My supplier sent me clay that has bentonite in it, claybody is the same =3D
as I've used for years, just with the addition of the bentonite. They =3D
would like for me to keep it as the cost of returning it is more than =3D
the clay. I can make it work for low shallow forms, but am having =3D
trouble with anything over 15 inches high. It just seems to collapse =3D
when I collar or try to shape it. It's also so sticky, seems like I'm =3D
spending alot of time just trying to get the goop off my hands to =3D
continue throwing. Is there anything to put in my throwing water that=3D=
20
will make this more workable for me? Also on tall forms, the surface on =
=3D
the top of the pot dries before I finish pulling up the wall. Any hope =3D
for this clay, used 300lbs and 700 to go,
I'm real tempted to return it but want to make sure I try everything =3D
before that. =3D20
Thanks, Annabelle in Naples Fl
Cindy Strnad on sat 5 may 01
Hello, Annabelle.
You'll get more knowledgeable advice than mine, but I'll take a stab at y=
our
problem anyway. It's my guess that not only will you have trouble throwin=
g
and forming this clay, but you will also find it cracks easily during
drying.
Bentonite has extremely fine particle size. If I were stuck with this cla=
y,
I'd first try mixing in both fire clay and grog, because I have a
pugger/mixer. However, if I didn't have one, I think I'd go with just the
grog at first. Maybe a cup full or so for a 25 lb block. Keep in mind I'm=
a
dump cook (except for glazes and wines), so my usual method of adding gro=
g
is just to dump some in. If you're the exacting type, you'll probably wan=
t
to do better than this. But try it--try adding some grog, and see if it
helps.
If you don't have any grog, don't want to wait for delivery, and don't mi=
nd
taking a chance, just go out to the beach (or your garden spot) and get
yourself a bucket of sand (the slightly coarse stuff, not the really powd=
ery
stuff) and try a bit of that. The salt in the beach sand might even do
interesting things. Better try just a little bit at a time.
Look at it as a fun experiment and just see what you can find out. Almost
makes me wish I were back in FL. So many cool things to play around with.
But we have cool stuff here, too.
Best of luck,
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
iandol on sun 6 may 01
Dear Annabelle,
Aaprt from de-watering, throwing dry or with slip, I offer the following =
as a long shot.
Try mixing some Aluminium Hydrate powder into a small batch, just a =
small sprinkle, or some Aluminium Sulphate, then wedge and knead well. =
The idea is to increase the concentration of high charge cations in the =
water, which should assist flock formation without negating the benefits =
of the Bentonite. Think in terms of about one gram per kilo or less.
Best regards,
Ivor Lewis. Redhill, South Australia.
Craig Martell on mon 7 may 01
Karen G sez:
>Mixing in dry macaloid (and probably also bentonite)
>results in a micro-bubble porous consistency of the
>clay which no amount of re-de-airing pugging or
>wedging can get out. It's like trying to wedge a
>marshmallow.
Hello Karen:
I would agree that blunging stuff like bentonite, macaloid, or vee gum t,
is very beneficial when these minerals are added to claybodies. I've
noticed that porcelain bodies with any type of montmorillonite plasticize=
r
will contain micro air pockets that can be a real pain.
In the past, I've dough mixed porcelains in my mixer and just added the v=
ee
gum t to the dry and batched for about 15 minutes before adding water and
finishing the mix. With this method, I do get some micro bubble problems
and deairing doesn't get rid of all that stuff. But, I've never had the
porcelain wedge like a marshmallow. When I do blunge the vee gum t prior
to adding to the mix I get less of the small air bubbles but there's not =
a
marked difference in the consistency of the clay. It's better, but not
that big of a deal. I think it would be really impractical to have to
blunge plasticizers and let them sit overnight before mixing. When I mix
clay, I like to do somewhere around a ton a day and I don't think I could
handle blunging enough stuff in advance.
regards, Craig Martell in Oregon
Alisa og Claus Clausen on mon 7 may 01
Dear Annabelle,
I have tried various clays from various suppliers befored I settled on =
two I use regularly. Two of the clays were bentonite white clays. =
Identical except one had no grogg and other had 20% 0,5mm grogg.
The no grogg was a pasty, slap clay I could not work very much. It was =
sticky and very relaxed about getting any height. The big sister with =
grogg was easier to get height, but very slap when it came to forming. =
It did not hold a distinct form well, always sort of buldging where I =
wanted a curve. I ended up using it for slip with colorants and I also =
just colored it with oxides to throw as rims on my other clays.
Wish this was more positive.
I had only about 40 kilo so it was not troublesome to use it up.=20
Best regards,
Alisa in Denmark
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