[Clayart] glazing questions/
jrodgers113 at gmail.com
Sat Oct 9 15:24:59 UTC 2021
Though I do a good bit of wheel work and slab building now, I began clay
work doing slip casting, mostly with porcelain. That later expanded to
include B-MIX specifically for pottery purposes. The porcelain remained in
the realm of figurines. But with both, I made/make my own slip. Viscosity
with these is critically important. When I began making pottery I realized
having the right viscosity for a particular glaze was important. It affects
how much glaze material adheres to the bisqued pot for a specific time of
immersion. I most often dip my pots. I check the thickness of a glaze
before dipping using a viscosimeter - basically a cup with a calibrated
orifice in the bottom. When filled with glaze, the time to drain completely
through the orifice is the measure of the viscosity. This operation is
pretty much like Mel says. My operation is not near as big as his, so I
just use the small commercial viscosimeter. It's basically the
viscosimeter you can pick up at your local paint store. However, I get mine
from New Mexico Clay. I prefer this because I also use this to measure the
viscosity of my clay slip. But I think mine and Mel's technique is pretty
much the same. His tools are homemade, I bought mine ready made. But the
goal is the same. Right viscosity, flow, and time equals excellent glaze
application, and most likely an exquisitely finished pot.
On Sat, Oct 9, 2021 at 7:28 AM mel jacobson <melpots at mail.com> wrote:
> I have had several folks email me with questions about precision glazing.
> Japanese technique.
> Two basic things are- a good clock with a big second hand, and dippers for
> the glaze bucket.
> In kyoto we used a big old electric clock with the hour and minute hand
> cut off.
> you counted the seconds the glaze was in the bucket, or seconds an open
> pot was full of glaze.
> in most cases 10 seconds was max. of course we tested the water content,
> or thickness of all glazes.
> A dipper was in each bucket. about a cup of glaze. I use old broom handles
> and measuring cups from
> the dollar store. I gorilla glue them and then wrap with duct tape. The
> dipper is a perfect stirring
> tool before you use the glaze each time. for example...you fill a large
> mug with white glaze, count
> to six seconds, pour it out. every mug gets the same timing. next you stir
> again, hold the mug upside down
> and push into the colored glaze. six seconds...pull out and rotate the mug
> so the drop of glaze goes around
> the rim one time. (in japan we used about 90 percent white glaze so it was
> very easy...just stir, fill and
> pour and rotate. Timing was always the same.
> If you layer glazes, develop a timing for each dip. So, base glaze 4
> seconds, 2 second dip in glaze 2 and
> 1 second in glaze 3. As time goes on, you learn the seconds that each
> glaze is in the bucket.
> So, in my case I am much more casual as I have been glazing for 60 years.
> I can stick my finger in a
> glaze and say to self...`2 cups of water`. I know shino is in the bucket
> for 6 seconds. it is a thick glaze.
> I only use gum in one glaze. that gets 2 seconds extra, as it not the
> glaze that is thick, it is the gum.
> So, for my white glaze I use a two cup plastic measuring cup with a nice
> sharp spout. no drips.
> Between Tonka and Farm I must have about 50 dippers of various sizes. Some
> glazes are only decorative so
> I use a quarter cup measure.
> I do not use very much hot wax on my pot bottoms. Don't need it. My foot
> rings fit my fingers. my faceted
> mugs have nice angles to grab for dipping. I am conscious of glazing when
> cutting foot rings. I never make
> `pseudopod rings`...false feet. I test the grab for glazing.
> If I have dozens of one type of pot, I sit and have the buckets between my
> legs...glaze and place on boards
> on the table next to me. Standing for hours glazing is a big pain. I find
> ways to sit.
> I start each glaze sessions by cleaning up tables and floor. I use an
> electric drill motor with a good
> paint mixing tool. I keep it in the buckets for minutes to get all the
> materials mixed. Then the dipper
> can just pick up the sunken thick glaze and bring it to the top. Don't
> glaze your pots with colored water,
> the good stuff is on the bottom. A great deal of glaze drops to the bottom
> in ten minutes. The most important
> issue is the dipper always stirring the glaze before you dip. It does
> become automatic. And, the dollar store
> has all kinds of measuring cups with handles. They work well. Of course
> here we have about a thousand scrap wood
> handles in our wood shop. You can always go to the big box store and get
> dowel rod. (have you checked prices? a sheet
> of 3/4 inch plywood. $85.) But, we always save the handles on old brooms
> and such.
> So, some thoughts,
> website: www.melpots.com
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