Patricia S. Thompson on wed 11 nov 98
Patricia S. Thompson
Pthompson@postmark.net
When I brush a glaze on my tall vases, I have difficulty getting an
even coat of glaze. Since I make very few of these and make up small
amounts of glazes, brushing seems to be the most economic technique.
(I do not have the equipment to spray a glaze.)
Does anyone have any suggestions to make the brushing go more
smoothly and the application come out more even? Type of brush,
adding something to the glaze to help the flow,etc?
Thanks,
Pat
James Norton on thu 12 nov 98
Patricia S. Thompson wrote:
> ----------------------------Original message----------------------------
> Patricia S. Thompson
> Pthompson@postmark.net
> When I brush a glaze on my tall vases, I have difficulty getting an
> even coat of glaze. Since I make very few of these and make up small
> amounts of glazes, brushing seems to be the most economic technique.
> (I do not have the equipment to spray a glaze.)
>
> Does anyone have any suggestions to make the brushing go more
> smoothly and the application come out more even? Type of brush,
> adding something to the glaze to help the flow,etc?
>
> Thanks,
> Pat
Pat,
Be sure to add CMC gum to the glaze. Start by adding a small amount and
test for brushing on a bisque pot.
If the glaze dries too quickly so that it can't be brushed out smoothly,
keep adding CMC until it brushes easily.
Dilute your glaze with enough water so that about 3 coats of application are
needed, waiting between coats until the previous
one has dried enough to apply another without disturbing it. Be sure to
have enough opacifier in the mix, 5% tin or 10%
Zircopax. Sometimes a teaspoon of glycerin per 100 grams of glaze helps.
I make up a stock supply of CMC dissolved in water, so that I can just add a
teaspoon or so to the mix.
Jim
Geoff Walker on fri 13 nov 98
Not an expert in brushing glazes, but I know that when "writing" on pots
with oxides and a fine brush, glycerine in the mix makes it flow so much
more easily.
Hope this helps,
Geoff. (Not ducking as low this time ...)
Linda Randall on fri 13 nov 98
Can you give me some idea of proportions of glycerin to glaze, oxides,etc
Linda R.
John Hesselberth on sat 14 nov 98
Geoff Walker wrote:
>----------------------------Original message----------------------------
>Not an expert in brushing glazes, but I know that when "writing" on pots
>with oxides and a fine brush, glycerine in the mix makes it flow so much
>more easily.
>Hope this helps,
>Geoff. (Not ducking as low this time ...)
When you dip pots in glazes you want the glaze/water dispersion to go
right to the pot, absorb quickly and be dry to the touch almost as soon
as you take the pot out of the glaze. To achieve this you want the glaze
to be on the flocculated end of the scale. Hence the large number of
posts in recent months on adding epson epsom salts after first making
sure you have enough clay in your glaze recipe for there to be something
to flocculate. Other materials that can serve as flocculants are calcium
sulfate, vinegar or calcium chloride.
When you brush on glaze you want just the opposite. You want the glaze
dispersion to stay fluid enough on the surface of the pots, for at least
a few seconds, so the brush marks disappear via the glaze flowing. This
means you want to be on the deflocculated end of the scale. I would
recommend add a deflocculant in very small quantities (probably a drop at
a time if you are only working with a cup or less of glaze--you can go
too far and end up with a mess) until you see the improvement you want.
This, by the way, is exactly the same mechanism that is used to make
paints flow well without leaving brush marks.
One of the best deflocculants is sodium silicate--this is the one most
often used in slip casting where you want the clay suspension to be fluid
at very high solids levels--, but sodium carbonate, potassium carbonate
and sodium hydroxide (strong base--handle with care) can also be used.
There is a much more thorough discussion of all this in Hamer & Hamer
under both Flocculation and Deflocculation.
John Hesselberth
Frog Pond Pottery
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"The whole aim of practical politics is to keep the populace alarmed, and
hence clamorous to be led to safety, by menacing it with an endless
series of hobgoblins, all of them imaginary." H.L. Mencken, 1925
gwalker on sat 14 nov 98
Linda,
I am sorry I cannot be more accurate at this moment ... my Brother does
the glazing and writing on pots, and is away for a few more days doing a
show for me. However, I would start with about a tablespoon of glycerine
in about a pint of glaze. Add more if you are still not having luck.
Sorry to sound so vague. Give me a few days and I will be able to be
more specific.
Best of luck,
Geoff.
James Norton on sat 14 nov 98
Linda Randall wrote:
> ----------------------------Original message----------------------------
> Can you give me some idea of proportions of glycerin to glaze, oxides,etc
>
> Linda R.
Linda,
I use one teaspoon to every 100 grams of dry glaze.
Jim
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