Ama Menec on wed 16 jun 04
Due to having Anglacised many American 06 glaze recipies, I am finding I am
using Soda Ash for the first time, and sometimes quite a lot of it. I've
noticed that some of the glaze slops are developing crystals like small
pieces of flat glass in them, but not always the ones with the most Soda
Ash. I'm assuming this is a Ph difference between the slops or some
interaction between materials, but have no idea how to prevent it. Any
suggestions from potters who use Soda Ash regularly? Thanks,
Ama Menec, Devon, UK.
Ivor and Olive Lewis on thu 17 jun 04
Dear Ama Menec,
I think you may have been experiencing some rather warm weather
recently. If your glaze buckets were not sealed then evaporation is
taking water from your slop, concentrating it to an extent that there
is insufficient water to keep the soluble soda in solution. Added to
that, the crystals sound like Sodium Decahydrate, a substance that is
composed of a large quantity of "Water of Crystallisation" as well as
your original anhydrous sodium carbonate.
Take some of the crystals and set them aside so that they dry. Watch
to see if they develop a white coating. If they do, get back to me.
Best regards,
Ivor Lewis. ( Who once worked in Devon and knew Laurie George, a
Painter of much renown of Paignton)
Redhill,
S. Australia.
----- Original Message -----
From: "Ama Menec"
To:
Sent: Wednesday, 16 June 2004 6:15
Subject: Soda Crystals in the Glaze Slop.
> Due to having Anglacised many American 06 glaze recipies, I am
finding I am
> using Soda Ash for the first time, and sometimes quite a lot of it.
I've
> noticed that some of the glaze slops are developing crystals like
small
> pieces of flat glass in them, but not always the ones with the most
Soda
> Ash. I'm assuming this is a Ph difference between the slops or some
> interaction between materials, but have no idea how to prevent it.
Any
> suggestions from potters who use Soda Ash regularly? Thanks,
>
> Ama Menec, Devon, UK.
>
>
______________________________________________________________________
________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your
subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Steve Mills on thu 17 jun 04
Hi Ama,
Are you in a hard water area? I am here in Bath (a bit north of you!)
and it has on occasion produced some interesting problems not dissimilar
to yours. I now use rainwater exclusively in my workshop; problems gone!
Steve
Bath
UK
In message , Ama Menec writes
>Due to having Anglacised many American 06 glaze recipies, I am finding I =
>am
>using Soda Ash for the first time, and sometimes quite a lot of it. I've
>noticed that some of the glaze slops are developing crystals like small
>pieces of flat glass in them, but not always the ones with the most Soda
>Ash. I'm assuming this is a Ph difference between the slops or some
>interaction between materials, but have no idea how to prevent it. Any
>suggestions from potters who use Soda Ash regularly? Thanks,
>
>Ama Menec, Devon, UK.
--
Steve Mills
Bath
UK
Ama Menec on fri 18 jun 04
Dear Steve, Ron and Ivor,
Thanks for your thoughts so far, most interesting. No, I'm not in a hard
water area here, we're on good Devonian Sandstone and rich red clay, with a
bit of Dartmoor granite for good measure. And it's only some of the glazes
this is happening to, and not necessarily in the strongest Soda solutions
either.
What I have also noticed is that some of the Soda Ash containing glazes are
producing a bloom as they dry; much as you would get on Egyptian paste, and
this bloom remains after firing. As I am firing mostly non-functional
sculptures, this is an added bonus, giving more depth and texture, and I'm
delighted!
Ron, you're right, we have had some uncharacteristically hot weather here in
Devon, UK, (hotter than Greece some days!!), but I'm finding the thicker
slops don't have this problem. In all I've made about 50 tests lately, about
half must have soda ash in them, but only a handful have crystals forming,
which is why I wondered if it may be a Ph issue? I shall try out your
suggestion of seeing if the drying crystals produce a white coating Ivor and
let you know. Ron, I'll let you know some of the recipes it's happening to
and some that it's not happening to....May take a few days as my computer is
not in the same place as my studio. Thanks for your thoughts on this,
Ama, Devon, UK.
| |
|
