Carty Ellis on mon 6 mar 06
I've looked at the messages on clayart and I don't see an 'exact' answer
to this question. I did see where some folks add veegum (didn't mention
veegumCER) to the dry glaze mix. So here is my situation.
I've been mixing majoilca bases (Ostermann and Arbuckle) and have had
terrible time geting the base glaze to have hard surface. Tried laundry
stach to no great effect. Finally bought a pound of veegumCER and brushes
beautifully and has nice hard surface to decorate. Been using OM4 or
Tennessee #5 ball clays.
Using the veengumCER is my question. My formulas for the majolica bases
have been 100 gm dry mix 100 ml water and I usually add a smidge
(scientific term) more water. For the veegumCER I replaced the bentonite
component with equal amount of veegumCER and disolved it in the water
first. Then added the dry glaze to this mucous-like solution. Really
difficult to mix in the dry glaze, and always add at least another 10 to
20 ml of water. Then I tried to seive - took FOREVER to get through 80
mesh sieve.
Two questions, - no three - 1. Is it really this difficult or have I
gotten creative? 2. Is the 1 for 1 bentonite to veegumCER correct? and 3.
do I have to predissolve or just add the dry veegumCER to the dry glaze
mix and be sure to let the glaze rest for a day before I use it?
I will admit - this is really great brushability for the glaze base. And
very hard surface. I like what it does - would like it to be simpler.
Craig Martell on mon 6 mar 06
Hello Carty:
This is all pretty simple once you have things figured out.
The general rule of thumb is to use one half the amount of vee gum for a
bentonite substitution. This will depend on the clay content of the glaze
so you can start there and add more if you need to. I try and use as
little as possible because of the expense and too much of any fine grained
plasticizer/suspender will slow the drying time of the glaze.
As far as mixing goes, add the vee gum to the total water volume of the
glaze. If you are mixing a 500 gram batch add the vee gum to 500 ml of
water and blunge it very well. I blunge in the vee gum first and then the
clay before adding the rest of the dry ingredients and doing the final
mixing. It should screen much better then and you'll have a nice
homogenous mix. You can add more water if you need it before or after
screening.
regards, Craig Martell Hopewell, Oregon
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