John Post on fri 12 may 00
>I guess I just don't know how to look it up in Hammer but I'm wondering
>what's best to add to a glaze to harden the surface so it doesn't dust
>off while handling. My local ceramic supplier lists CMC, v-gum and
>macaloid as additives to help with hardness but I'm not sure which is the
>best. It also says that they aid in suspension of the glaze. Does that
>eliminate the need for the bentonite that I add to some glazes?
>Cheryl Litman ---------- Somerset, NJ --------- email:
>cheryllitman@juno.com
Hi Cheryl,
One of the most useful ways that I have found to keep a glaze from being
too powdery is to reformulate it to have more clay in it. You didn't post
the recipes so I'm not sure how much clay is in your glazes. I find that
glazes that have less than 10% clay in them are most likely to be
candidates for being powdery.
I have had some successes replacing the feldspars and gerstley borate in
glazes with frits. By using frits I am able to get more raw clay into the
glaze and thus make a better handling slurry that sticks to the pot better.
It requires some testing on your part, but I would be willing to
reformulate the glaze for you if you want me to. You can post it to the
list or directly to me if you like. And like Ron Roy, I can keep your
recipes confidential if you need me too.
John Post
Sterling Heights, Michigan USA
e-mail waverock@c3net.net
Website http://www.c3net.net/waverock
WHC228@AOL.COM on wed 24 may 00
Cheryl
If you just need to keep the glaze from dusting off the pot while you are
handling it try liquid starch. It is cheap and available at any grocery store.
Bill
friedlover on wed 24 may 00
Good questions, I'm also interested in replies.
I do know that the CMC is very useful for brushability and suspension, and
doesn't seem to affect any other qualities of the glaze, from what I've seen
so far. Rhonda
----- Original Message -----
From: Cheryl L Litman
To:
Sent: Wednesday, May 24, 2000 5:44 AM
Subject: ?best surface hardener for glaze
> I guess I just don't know how to look it up in Hammer but I'm wondering
> what's best to add to a glaze to harden the surface so it doesn't dust
> off while handling. My local ceramic supplier lists CMC, v-gum and
> macaloid as additives to help with hardness but I'm not sure which is the
> best. It also says that they aid in suspension of the glaze. Does that
> eliminate the need for the bentonite that I add to some glazes? If it's
> a suspension aid is it deflocculating the glaze? When would you add
> something like Darvan to a glaze? Is there a good reference out there
> for understanding glaze additives and when you'd need them? Also what
> would you add to make a glaze more brushable?
>
> Cheryl Litman ---------- Somerset, NJ --------- email:
> cheryllitman@juno.com
>
> ***Experience is what allows you to recognize a mistake......when you
> make it again.***
>
>
____________________________________________________________________________
__
> 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.
Ron Roy on sun 4 jun 00
Hi Cheryl,
I usually start by subbing ball clay for kaolin - some or all depending on
the amount of kaolin. If it needs more hardening I then put in some
bentonite.
The soluble salts will do the job as will the binders but I only would use
them as a last resort.
Use a calculation program to keep the Al2O3 the same - you will have to use
more ball clay to get the same amount - and then lower the silica to get
the ratio back to the original.
RR
>I guess I just don't know how to look it up in Hammer but I'm wondering
>what's best to add to a glaze to harden the surface so it doesn't dust
>off while handling. My local ceramic supplier lists CMC, v-gum and
>macaloid as additives to help with hardness but I'm not sure which is the
>best. It also says that they aid in suspension of the glaze. Does that
>eliminate the need for the bentonite that I add to some glazes? If it's
>a suspension aid is it deflocculating the glaze? When would you add
>something like Darvan to a glaze? Is there a good reference out there
>for understanding glaze additives and when you'd need them? Also what
>would you add to make a glaze more brushable?
>
>Cheryl Litman ---------- Somerset, NJ --------- email:
>cheryllitman@juno.com
>
>***Experience is what allows you to recognize a mistake......when you
>make it again.***
>
>______________________________________________________________________________
>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.
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
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