Kate Johnson on wed 8 dec 04
Hi again all...the other day Paul Lewing reminded me that the traditional
honey glaze was made with lead, and so it was--as I answered, part of my
quest is to reproduce the look without the questionable ingredient, and
hoping this is possible.
I did notice as I browsed my new books that some recipes still call for lead
or lead basilicate (sp?)--someone here, can't remember who, was saying we
worry more than we need to about lead in glaze, but I do consider it a good
point to be able to tell people that my glazes are lead-free. Just not sure
I can really get from here to there without it!
(Still waiting for a new batch to go into the kiln with a stronger
concentration of red oxide, mixed to a fair-thee-well, maybe THAT will
work!)
I have noticed also that Mary Wondraush uses lead in her honey glaze to
reproduce those glorious early-style plates...but many of her things are
presentation plates, not intended to be used for food. Anyone have any
further thoughts on this?
Regards,
Kate, still determined to forge forward into the past...
Cindy on wed 8 dec 04
Hi, Kate,
I think there is a ^6 glaze in the archives that will meet your needs. It
was "honey" something. Very pretty. I don't have the recipe handy, but if
you can't find it, write me and I'll try to look it up. It was clear amber,
sometimes with little bubbles under the surface.
In my understanding, lead doesn't have a great function in mid and high fire
glazes.
If you do fire pottery with lead glazes, be aware that the lead gets into
the brick of your kiln and anything you fire afterward may have lead in it.
Merry Christmas,
Cindy in SD
Earl Brunner on wed 8 dec 04
You said they were new books. What is or are their copyright dates? There
are books out there that are only 20 or 30 years old that do not follow
current thinking on some of the safety issues. There are a large number of
people on this list. There are probably an equally large number of opinions
on different things. We need to be careful what we pick and chose to
follow. It's a safety issue AND a liability issue. MOST of the "experts"
would discourage the use of lead. Period.
Earl Brunner
Las Vegas, NV
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Kate Johnson
Sent: Wednesday, December 08, 2004 6:41 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: lead in traditional honey glaze
Hi again all...the other day Paul Lewing reminded me that the traditional
honey glaze was made with lead, and so it was--as I answered, part of my
quest is to reproduce the look without the questionable ingredient, and
hoping this is possible.
I did notice as I browsed my new books that some recipes still call for lead
or lead basilicate (sp?)--someone here, can't remember who, was saying we
worry more than we need to about lead in glaze, but I do consider it a good
point to be able to tell people that my glazes are lead-free. Just not sure
I can really get from here to there without it!
(Still waiting for a new batch to go into the kiln with a stronger
concentration of red oxide, mixed to a fair-thee-well, maybe THAT will
work!)
I have noticed also that Mary Wondraush uses lead in her honey glaze to
reproduce those glorious early-style plates...but many of her things are
presentation plates, not intended to be used for food. Anyone have any
further thoughts on this?
Regards,
Kate, still determined to forge forward into the past...
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Ivor and Olive Lewis on thu 9 dec 04
A strong yellow orange which imitates traditional Lead Iron Oxide
Honey glaze can be created at stoneware temperatures (^8) with a
transparent Soda Felspar glaze coloured with about 10% Manganese
Dioxide. Adjustments to prevent crazing on most clays can be achieved
with small additions of Petalite.
Yes! Yes! I know... the dreaded poisonous Manganese syndrome. But this
is a good substitute if you do not wish to use the Lead Bisilicate
Earthen ware route. And it really does look like real bee's honey.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Kate Johnson on thu 9 dec 04
Hi Earl, and thank you...yes, I definitely plan to avoid lead, however I may
do it. Just being frustrated by my difficulty in getting where I want to be
without it.
> You said they were new books. What is or are their copyright dates?
One is _Mary Wondraush on Slipware_, which is a revised 2001 edition of her
original 1986 book. In many places she has indeed marked revisions with an
asterisk, so you know, but the does refer to "a 'safe' fritted form of lead,
such as lead bisilicate or lead sesquisilicate." (pg. 36-37, not 35 as the
index says.) She gives a recipe for glaze with lead sesquisilicate. Are
those indeed safe?
The Tony Birk book, _The Complete Potter's Companion_ (originally 1993,
republished in 1998 and 2003) also talks about "lead 'frit,' lead which has
been combined with silica in a milted state and ground to a nontoxic
powder." (Pg. 114.) He goes on to say that even those have been banned by
most classes, and replaced sith borax or borax frits.
I know I've seen glaze recipes in some of the other books that include lead,
which is what got the wind up for me...
There
> are books out there that are only 20 or 30 years old that do not follow
> current thinking on some of the safety issues. There are a large number
> of
> people on this list. There are probably an equally large number of
> opinions
> on different things. We need to be careful what we pick and chose to
> follow. It's a safety issue AND a liability issue. MOST of the "experts"
> would discourage the use of lead. Period.
Understood. I don't plan to use it, and in fact definitely plan not to,
just curious about its inclusion in newish/revised books.
Best--
Kate
Kate Johnson on thu 9 dec 04
Hi Ivor!
>A strong yellow orange which imitates traditional Lead Iron Oxide
> Honey glaze can be created at stoneware temperatures (^8) with a
> transparent Soda Felspar glaze coloured with about 10% Manganese
> Dioxide. Adjustments to prevent crazing on most clays can be achieved
> with small additions of Petalite.
Unfortunately my particular challenge _does_ seem to involve red earthenware
clay, which is what was used by the colonial potters who inspire me. Can't
fire it that hot, am I not correct?
>
> Yes! Yes! I know... the dreaded poisonous Manganese syndrome. But this
> is a good substitute if you do not wish to use the Lead Bisilicate
> Earthen ware route. And it really does look like real bee's honey.
Drooling here...
Best--
Kate
Ron Roy on thu 9 dec 04
Anyone should think very carefully about using lead - it is controlled and
the law is specific - if it can hold liquid it has to be labeled - not for
food - impressed into the clay - even has to be a certain size up here in
Canada - unless it can pass the leach test - imagine - testing every batch
of pots to be sure the glaze does not leach lead over the limits.
Either that or a hole in every piece so it cannot hold liquids.
Lead is insidious - any potter working with lead is going to absorb some of
it - the question becomes - will it be a problem for them and when.
Anyone working lead glazes should have blood levels checked regularly.
RR
>I have noticed also that Mary Wondraush uses lead in her honey glaze to
>reproduce those glorious early-style plates...but many of her things are
>presentation plates, not intended to be used for food. Anyone have any
>further thoughts on this?
>
>Regards,
>Kate, still determined to forge forward into the past...
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Ama Menec on fri 10 dec 04
I use lead bisilicate clear glazes all the time, and they are entirely clear
and colourless. Any lead glaze recipes I've seen that are 'honey coloured'
are this colour because of the addition of either iron oxide, or red
earthenware clay, in the recipe. By the way, Mary Wondraush has been eating
off lead glazed pots and plates all her life....they are not just for
sitting on the dresser to look at; even 'tho they are lovely!
Ama Menec, Totnes, Devon, UK.
Ivor and Olive Lewis on fri 10 dec 04
Dear Kate,
True, True. Not a chance with red clay, a fact I appreciated and
acknowledged in my message.
But you might try experimenting with one of the low temperature MP
high sodium frits over a white slip on your red clay, just to find out
if things are possible.
But I do appreciate your dilemma when you are producing authentic
reproductions.
Have a good Festive season and enjoy.
Best regards
Ivor
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