Mondloch on tue 7 oct 03
Hi,
Can anyone tell me what would work better then Darvin 811 to defloc an ash
glaze?
I've got a batch of glaze mixed up that I'd like to get to work.
I had made and used up a small batch (1000gr) of a wood ash glaze- worked
fine. Now I've mixed a larger batch (10,000 gr) but can't get it right in
the bucket. It turned to very thick pudding after sitting. I added some
Darvin 811,but it didn't seem to do anything. The Darvin works good in a
high zinc glaze I have that likes to pudding. In fact I have to be very
careful not to add too much to that glaze or it settles like a rock. So I'm
thinking the chemistry is different to defloc an ash glaze??
I've already ran it back through the strainer and got it applying to the
right thickness, but it's still cracking up too much when it dries. Right
now, the volume of glaze is about double of a regular glaze for the same
weight materials. I'm applying to greenware by dipping/pouring for cone 10
single firing.
The recipe:
40 wood ash
30 custer
20 ball clay
10 flint
add: 1% cobalt
(mixed with extra water, screened 80m, extra water and coarse ash removed)
I suppose next time I could reduce the ball clay and/or replace it with
kaolin? But I'd sure like to figure out this floc/defoc thing once- always
confuses me. Maybe I don't need to understand it completely, my Hamer book
totally loses me on this one. I just want to know what to add to my bucket
of ash glaze. ;)
Thanks for any help,
Sylvia
---
Mark & Sylvia Mondloch
Silver Creek Pottery & Forge
W6725 Hwy 144
Random Lake ,Wi 53075
HotArt@silvercreekpottery.com
http://www.silvercreekpottery.com
Craig Martell on tue 7 oct 03
Sylvia asked:
>Can anyone tell me what would work better then Darvin 811 to defloc an ash
>glaze?
>I've got a batch of glaze mixed up that I'd like to get to work.
Hi Sylvia:
If this is unwashed ash, the following comments would apply.
Darvin won't do anything. If this is the reaction that I think it is,
there's really nothing you can do now to make the glaze useable. Too much
soluble alkali from the ash causes the "pudding" effect and once this takes
place, you're out of luck. Adding acids to counter the problem doesn't
work either. You have to use unwashed ash very quickly, as in, the same
day it is mixed. You can also wash the ash to remove some of the solubles
and this gets rid of the problem. This is what I do to my ash glazes.
If you add water to this glaze until it seems to be at the right
consistency, your glaze coat will be too thin after it dries. Most of what
you put on the pot will be water.
It's not the clay either. You don't need to exhange kaolin for ball
clay. The probelm is the wood ash.
regards, Craig Martell Hopewell, Oregon
iandol on wed 8 oct 03
Dear Sylvia Mondloch,
You say <<(mixed with extra water, screened 80m, extra water and coarse =
ash removed)>>
Is that Ash you are using unwashed, single washed or thoroughly washed =
before it is mixed with the other ingredients?
From memory, I recall that Potassium carbonate can have a similar =
behaviour to Sodium Carbonate in causing deflocculation and that an =
excess does something similar to reflocculating the batch. It might be =
in Hutchinson Cuff's book. If the ash was unwashed or partly washed, =
your treatment of the ten kilo batch in screening with additional water =
may have been inadequate to remove as much Potassium electrolyte as was =
taken form the one kilo batch.=20
I would test a sample with Hydrochloric acid then rewash and see how it =
settles and deflocculates.
Best regards,
Ivor Lewis. Redhill, South Australia
Lee Love on wed 8 oct 03
----- Original Message -----
From: "Craig Martell"
> work either. You have to use unwashed ash very quickly, as in, the same
> day it is mixed. You can also wash the ash to remove some of the solubles
> and this gets rid of the problem. This is what I do to my ash glazes.
Not all unwashed ash glazes behave this way. Mine haven't (yet.)
For me, the soluables are very important so I never wash them out. When I
buy ash from the co-op, it is washed, but I'd prefer it wasn't. I add soda
ash to replace the soluables when I use washed ash. But it does sound
like maybe it is a problem in Sylvia's glaze.
> If you add water to this glaze until it seems to be at the right
> consistency, your glaze coat will be too thin after it dries. Most of
what
> you put on the pot will be water.
This is why the scratch test is so important. You actually look
at the thickness of the glaze on your test piece. What you do is take a
piece of bisque or greenware, the same thickness as the work you want to
glaze is. I sponge the bisque, but just dust the greenware. Mix
glaze thoroughly, dip test piece in the glaze, hold for the same amount of
time as you would the actual work. Pull out and wait for the glaze to dry.
Scratch the surface to the bare clay and look at how thick the glaze
actually is. The thickness you want varies according to the glaze. You
have to experiement and then save a sample tile when it works to compare
against.
> It's not the clay either. You don't need to exhange kaolin for ball
> clay. The probelm is the wood ash.
Sylvia, you can still wash the glaze using the method we used at my
teacher's workshop. I don't know if it will work, but it is worth a try.
I don't know how it will effect the Darvin. We washed the ash at my
teacher's workshop twice a day for over a month, until the water was totally
clear and there was no scum on the surface. Always be careful about skin
contact when handling ash.
Put your glaze bucket where you can easily empty it. If you use
a siphon as I describe, you'll want the bottom of the settled water level in
the glaze bucket higher than where it will drain. A short length of
garden hose can be used as a siphon, I think ours was about 5' long.
Fill you container with more water. If you don't have enough room
in the container, put it in a larger container. Add lotsa water. Mix
well with a mixer. Let it set over night the first time. The next day,
you should see water looking like tea separated from the glaze. You can
ladle it out or use a siphon, holding the siphon in the top layer of water,
but not in the bottom layer of glaze. We filled the siphon at the tap and
then put a thumb over each end to hold the water in. Put one end in the
layer of water while your thumb is on the end and drop the other end on the
ground or bucket or drain, where you will drain the water to. We never
wore them, but you might wear rubber gloves if your hands are sensitive.
When the water is drained to the settled glaze level, add water and
mix. You can always top it off with water at the end of the mixing and
then manually stir. If you top it off in the beginning, the mixer will
splash it out of the bucket.
Do this several times, until you have it as clear as you want.
After the first time, you can drain again as soon as the water separates
again.
Lee In Mashiko
Chris Schafale on wed 8 oct 03
Wonder if it would work to add a LOT more water (if
she has a container that big!) and then let it settle and
remove excess. Keep doing this, and might it
eventually work like washing the ash? Having said
that, I had this problem with a glaze once and in the
end had to throw it away.
Chris
Sylvia asked:
>Can anyone tell me what would work better then
Darvin 811 to defloc an ash
>glaze?
>I've got a batch of glaze mixed up that I'd like to get to
work.
Craig wrote in part:
Too much
soluble alkali from the ash causes the "pudding" effect
and once this takes
place, you're out of luck. Light One Candle Pottery
Fuquay-Varina, North Carolina, USA
(south of Raleigh)
candle@intrex.net
http://www.lightonecandle.com
Mondloch on wed 8 oct 03
Wow, thank you to everyone who weighed in on this, both online and off.
Opinions seem to vary alot.
In retrospect, I think the reason that I am having problems with the larger
batch is in how I mixed it. I probably used less excess water-
proportionately to the amount of ash- to mix it then I did with the small
batch, so the ash did not get "washed" as much. I mix a different ash glaze
in this size batch (a scrap glaze, ash, Redart, flint mix), but use a
smaller % ash so, assuming that I use about the same amount of excess water,
the amount of "ash washing" getting done would be higher in that one I
guess.
Last night, I added more water to the batch and was able to remove about a
gallon of water off the top this morning. I glazed a few pots with it and it
worked sort of ok- a little thinner coat then I'd like (I use the scratch
test ;)) and I rubbed it down as it dried to heal the cracking. I think if I
add and remove water a couple times before my next glaze session, it should
be fine.
I also set up a little experiment this morning- set aside four 2 cup
containers of the glaze. One with some more Darvan, one with a little soda
ash, one with Epsom salts, and one plain. I'll see how they settle out and
report back.
thanks,
Sylvia
Mark & Sylvia Mondloch
Silver Creek Pottery & Forge
W6725 Hwy 144
Random Lake ,Wi 53075
HotArt@silvercreekpottery.com
http://www.silvercreekpottery.com
> Hi,
> Can anyone tell me what would work better then Darvin 811 to defloc an ash
> glaze?
> I've got a batch of glaze mixed up that I'd like to get to work.
>
> I had made and used up a small batch (1000gr) of a wood ash glaze- worked
> fine. Now I've mixed a larger batch (10,000 gr) but can't get it right in
> the bucket. It turned to very thick pudding after sitting. I added some
> Darvin 811,but it didn't seem to do anything. The Darvin works good in a
> high zinc glaze I have that likes to pudding. In fact I have to be very
> careful not to add too much to that glaze or it settles like a rock. So
I'm
> thinking the chemistry is different to defloc an ash glaze??
>
> I've already ran it back through the strainer and got it applying to the
> right thickness, but it's still cracking up too much when it dries. Right
> now, the volume of glaze is about double of a regular glaze for the same
> weight materials. I'm applying to greenware by dipping/pouring for cone 10
> single firing.
>
> The recipe:
> 40 wood ash
> 30 custer
> 20 ball clay
> 10 flint
> add: 1% cobalt
> (mixed with extra water, screened 80m, extra water and coarse ash removed)
>
> I suppose next time I could reduce the ball clay and/or replace it with
> kaolin? But I'd sure like to figure out this floc/defoc thing once- always
> confuses me. Maybe I don't need to understand it completely, my Hamer book
> totally loses me on this one. I just want to know what to add to my bucket
> of ash glaze. ;)
>
> Thanks for any help,
> Sylvia
Craig Martell on wed 8 oct 03
Lee in Mashiko commented:
> Not all unwashed ash glazes behave this way.
Hello Lee:
Quite true. I depends on the composition of the ash and the amounts and
kinds of solubles that are being released. I've heard of some ash
flocculating badly during the washing process because of an abundance of
soluble alkali. This has never happened to me.
I think the way it works is: If the majority of released soluble is
Calcium, we see extreme flocculation. But if the released soluble is
Sodium, the opposite, deflocculation occurs. I've never had an ash
deflocculate. I'm just repeating what I've read in terms of possibilities.
Although I wash my woodash, I think it's just fine to use
unwashed. Tichane says that you can remove up to 25% of the fluxing action
of an ash by washing. Tichane and Phil Rogers differ on this. Tichane
prefers unwashed ash and Phil always washes his. It's interesting to
compare fired tests of washed and unwashed ash.
Probably the best way to use woodash is in a woodkiln. Then, you don't
have to wash, sieve, collect. or do anything to the ash. You just burn the
wood for heat and let the ash fly. :^)
>Sylvia, you can still wash the glaze using the method we used at my
>teacher's workshop. I don't know if it will work, but it is worth a try.
Good advice Lee. You and Chris S. are ahead of me. I didn't think of
this, but the two of you are right on.
regards, Craig Martell Hopewell, Oregon
Craig Martell on wed 8 oct 03
Chris suggested:
>Wonder if it would work to add a LOT more water (if
>she has a container that big!) and then let it settle and
>remove excess. Keep doing this, and might it
>eventually work like washing the ash?
Hello Chris:
Good thinking! The above suggestion would sure be worth a shot.
After this is done, the glaze would have to be applied to a pot and have
the thickness checked with the glaze and pot are totally dry. That's what
I would do anyway.
regards, Craig Martell Hopewell, Oregon
Bobbruch1@AOL.COM on thu 9 oct 03
Craig Martell Although I wash my woodash, I think it's just
fine to use unwashed. Tichane says that you can remove up to 25% of the
fluxing action of an ash by washing. Tichane and Phil Rogers differ on this.
Tichane
prefers unwashed ash and Phil always washes his. It's interesting to compare
fired tests of washed and unwashed ash.
I have found that glazes using washed ash tend to be less runny, and more
matte. The mattes tend to be uneven with flecks of browns and blacks which can be
appealing on certain types of work. The color will also be abit different
from the unwashed variant. This is especially true with white ash glazes. Similar
differences seem to exist in both electric and gas kilns.
As for glazes that seem like "pudding", I guess I get that at times with
various glazes, and never thought much of it, but then I brush glazes on in
multiple coats, so it doesn't seem to present a problem. If the "pudding is too
thin, just leave the bucket uncovered for awhile so some of the water can
evaporate and you will get a consistency that can be brushed effectively.
Bob Bruch
Lee Love on thu 9 oct 03
----- Original Message -----
From:
> I have found that glazes using washed ash tend to be less runny, and more
> matte.
Hi Bob,
I think, all other things the same, what you say above is true.
But washed ash glazes can be runny too.
Here is my runny Irabo, on a Shigaraki clay mug. It is made with
washed ash, but it is runny. The amount of shine depends upon how hot it
gets and how much fly ash gets on the piece:
http://www1.ocn.ne.jp/~ikiru/oct903irabo.jpg
I want to make my nuka more matt. The matt Hamada nukas I've
handled look underfired (there was a large variation of temps in his
noborigama. I'm thinking adding alumina/kaolin makes sense.
Lee In Mashiko
Mondloch on thu 9 oct 03
>
> I also set up a little experiment this morning- set aside four 2 cup
> containers of the glaze. One with some more Darvan, one with a little soda
> ash, one with Epsom salts, and one plain. I'll see how they settle out and
> report back.
>
Hi,
I finished my little experiment this morning...
All four samples had virtually the same amount of clear water on top (the
glaze had been thinned quite abit). I removed the clear water from each,
stirred them, and dip-glazed each sample on the outside a mug (same batch
of mugs, greenware). In terms of how "thick" the glaze was- the Epsom
sample was the thickest, then the plain, then the soda ash, and the
"thinnest" was the Darvan sample. The Epsom sample cracked up the worst (to
the point of falling off) and the Darvan sample the least. I then thinned
down the Epsom and plain samples because they had laid down a thicker
coating to see if the cracking would go away. Somewhat better but I think
the Darvan sample was still the best- some cracking around the handle joint,
but usable.
I still don't understand what this means, but there it is. Darvan 7 was
mentioned as being successfully used to defloc ash glazes, but I don't have
that on hand so used the Darvan 811 that I have. Would there be a difference
in how these two react in an ash glaze?
I also glazed a mug in my other ash glaze as a control and that worked just
fine.
Sylvia
---
Mark & Sylvia Mondloch
Silver Creek Pottery & Forge
W6725 Hwy 144
Random Lake ,Wi 53075
HotArt@silvercreekpottery.com
http://www.silvercreekpottery.com
Lee Love on thu 9 oct 03
Hi Sylvia,
If it is too thin with one application, can you do a second
application?
My unwash ash glazes often look "different in the bucket." So do
my soda ash shinos.
Good Luck,
lee in Mashiko
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