Dennis Mummert on wed 31 jan 01
Lesley;
Dishwasher dulling is almost a fact of life. Why the inside and not the
outside is a puzzle, but I will hazard a guess. I have noticed in some of
my glaze tests that the inside of a piece glazes differently than the
outside. Most heat transfer in a kiln is from radiation more than anything
else, and I suppose the insides are shadowed somewhat.
Dishwasher detergent is mainly sodium carbonate with a little surfacant and
coloring. It even etches certain types of glass used in tumblers, and
almost all of my coffe mugs that go thru the dishwasher have the bottoms
dulled due to having detergent water stand in them.
Another factor would be in how your glazes are applied. If you fill the
ware with glaze and paint another surface, the thickness will vary.
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Blue Rooster Pottery
Sent: Wednesday, January 31, 2001 7:53 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Maiolica Dinnerware
Hello:
I have had a query from a customer who is using our maiolica dinnerware on a
daily basis. She is concerned that her 4 year old maiolica mugs and pasta
bowls are DULLING on the interior where they come into contact with
food/beverages. She washes them in the dishwasher with no heat dry, doesn't
use any abrasives like SOS on surface.
The exterior and rims of the pieces are still as glossy as the day she
purchased them. Could the dullness be the acidity in the food reacting with
the dishwasher detergent and causing wear?
My base glaze is mostly frit 3124 with kaolin and a small amount of flint
fired to c/04. Look forward to some theories.
Thank you - Lesley, puzzling in the Great White North
____________________________________________________________________________
__
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
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Ceramic Design Group on wed 31 jan 01
o
>
> The exterior and rims of the pieces are still as glossy as the day she =
> purchased them. Could the dullness be the acidity in the food reacting =
> with the dishwasher detergent and causing wear?
> My base glaze is mostly frit 3124 with kaolin and a small amount of =
> flint fired to c/04. Look forward to some theories.
Any zircopax in this glaze for white/opacity? What clay body are you using?
Could be the detergent, which contains some alkali materials that are
reacting with the glaze. Your majolica base glaze sounds fairly standard,
most of them at that temperature are 3124, some EPK, maybe some flint to
help avoid crazing. Another theory is that if indeed you ware is dry footed,
even at cone 04 the clay is not vitrified. Water can be entering through the
unglazed foot and causing a reaction between the interior clay surface and
the glaze.
I would consider having your glaze tested for leaching, but I seriously
doubt that they will find anything. The frit is a pretty good glass, and if
you are not getting any crazing, then you have a pretty close coefficient of
expansion in the glaze and the clay.
Sounds to me more of a detergent issue, but to quote a colleague more
learned than I..
" You don't have to look for problems in ceramics...they will usually find
you!"
Hope that helps. Call me to discuss if you need to.
Best
Jonathan
Jonathan Kaplan, president
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
voice and fax 970 879-9139
jdkaplan@cmn.net
info@ceramicdesigngroup.net
Plant Location:
1280 13th Street Unit 13
Steamboat Springs CO 80487
(please use this address for all deliveries via UPS, comman carrier, FEd Ex,
etc.)
"Custom design and manufacturing for the ceramic arts, giftware and pottery
industries. Molds, models, and tooling for slip casting, jiggering and
hydraulic pressing. Consultation on technical issues such as clay bodies
glazes, and kilns."
Marianne Lombardo on wed 31 jan 01
I purchased a set of new dishes about 4 years ago, and have noticed that the
colours are very faded, and some colours have actually changed. When
comparing the bowls and plates used daily to some teacups that have never
been used (we like coffee mugs), the difference is astounding. All of our
glasses are etched and look awful too. Dishwashers are hell on dishes. The
appliance repairman once told me that the powered detergents were abrasive.
However, we've been using liquid detergents, so I don't think that's the
cause.
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
----- Original Message -----
From: "Blue Rooster Pottery"
To:
Sent: Wednesday, January 31, 2001 7:53 PM
Subject: Re: Maiolica Dinnerware
Hello:
I have had a query from a customer who is using our maiolica dinnerware on a
daily basis. She is concerned that her 4 year old maiolica mugs and pasta
bowls are DULLING on the interior where they come into contact with
food/beverages. She washes them in the dishwasher with no heat dry, doesn't
use any abrasives like SOS on surface.
The exterior and rims of the pieces are still as glossy as the day she
purchased them. Could the dullness be the acidity in the food reacting with
the dishwasher detergent and causing wear?
My base glaze is mostly frit 3124 with kaolin and a small amount of flint
fired to c/04. Look forward to some theories.
Thank you - Lesley, puzzling in the Great White North
____________________________________________________________________________
__
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.
Blue Rooster Pottery on wed 31 jan 01
Hello:
I have had a query from a customer who is using our maiolica dinnerware =
on a daily basis. She is concerned that her 4 year old maiolica mugs =
and pasta bowls are DULLING on the interior where they come into contact =
with food/beverages. She washes them in the dishwasher with no heat =
dry, doesn't use any abrasives like SOS on surface.
The exterior and rims of the pieces are still as glossy as the day she =
purchased them. Could the dullness be the acidity in the food reacting =
with the dishwasher detergent and causing wear?
My base glaze is mostly frit 3124 with kaolin and a small amount of =
flint fired to c/04. Look forward to some theories.
Thank you - Lesley, puzzling in the Great White North
Rod, Marian, and Holly Morris on thu 1 feb 01
Quite a while back, I read in my dishwasher manual that if you are
experiencing etching, you need to use less deterg. Since I read this, I have
cut way back on the deterg and I have no more etching. Also, the crud on the
outside bottoms of cups can usually be removed periodically with a quick
wipe of toilet bowl cleaner or lime cleaner. It can be mineral build-up
Given these facts, since the plates are already faded, you might try a wipe
with the de-limer to see if that is the issue. Don't let the stuff sit on
the dishes for any length of time, though. It WILL eat through the glaze.
Marian in Snowy Michigan
----- Original Message -----
From: "Dennis Mummert"
To:
Sent: Wednesday, January 31, 2001 9:04 PM
Subject: Re: Maiolica Dinnerware
> Lesley;
>
> Dishwasher dulling is almost a fact of life. Why the inside and not the
> outside is a puzzle, but I will hazard a guess. I have noticed in some of
> my glaze tests that the inside of a piece glazes differently than the
> outside. Most heat transfer in a kiln is from radiation more than
anything
> else, and I suppose the insides are shadowed somewhat.
>
> Dishwasher detergent is mainly sodium carbonate with a little surfacant
and
> coloring. It even etches certain types of glass used in tumblers, and
> almost all of my coffe mugs that go thru the dishwasher have the bottoms
> dulled due to having detergent water stand in them.
>
> Another factor would be in how your glazes are applied. If you fill the
> ware with glaze and paint another surface, the thickness will vary.
>
> -----Original Message-----
> From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
> Behalf Of Blue Rooster Pottery
> Sent: Wednesday, January 31, 2001 7:53 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: Maiolica Dinnerware
>
>
> Hello:
>
> I have had a query from a customer who is using our maiolica dinnerware on
a
> daily basis. She is concerned that her 4 year old maiolica mugs and pasta
> bowls are DULLING on the interior where they come into contact with
> food/beverages. She washes them in the dishwasher with no heat dry,
doesn't
> use any abrasives like SOS on surface.
>
> The exterior and rims of the pieces are still as glossy as the day she
> purchased them. Could the dullness be the acidity in the food reacting
with
> the dishwasher detergent and causing wear?
> My base glaze is mostly frit 3124 with kaolin and a small amount of flint
> fired to c/04. Look forward to some theories.
>
> Thank you - Lesley, puzzling in the Great White North
>
>
____________________________________________________________________________
> __
> 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.
>
>
____________________________________________________________________________
__
> 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.
>
Alice Chittenden on thu 1 feb 01
Marianne wrote "However, we've been using liquid detergents, so I
don't think that's the cause."
Marianne - think again. God knows how, but a couple of years ago one of
my kids got dishwasher liquid on the kitchen window over the sink. And
since the guilty party didn't bother to wash it off I now have
permanently etched spots on the glass. Although I haven't had any
problems with pottery, dishwashing has certainly taken a toll on my
glassware.
Alice
ferenc jakab on fri 2 feb 01
It seems to me that the inside is losing its lustre quicker because when you
stack a dish you stack it concave down precisely because you want the
greater surface contact from the sprayers. I.E. the inside of the bowl is
getting more contact with the chemical and greater mechanical application.
The outside is taking longer because the same part of the outside is not
always in contact with the spray. (clumsy sentence, but I hope you all
understand what I mean).
Feri
Ron Roy on sun 4 feb 01
There is no doubt, the glaze is being undone by acidic foods - that is why
it is happening on the inside only. The glaze is short of silica. It is
difficult to make stable glazes in the lowfire range.
Better to do your "maiolica" at cone 6 - that way you can vitrify the body
and better solve the functional aspects of your work.
A few of us did a group project a few years ago and I can supply some very
good looking "maiolica" glazes for cone 6. They are not tested for
durability yet - it would be a good project for someone.
Special care must be taken about where the decoration goes and how durable
it is - remember - the decoration on "maiolica" goes on top of the glaze -
makes it more difficult to make those parts durable.
RR
>I purchased a set of new dishes about 4 years ago, and have noticed that the
>colours are very faded, and some colours have actually changed. When
>comparing the bowls and plates used daily to some teacups that have never
>been used (we like coffee mugs), the difference is astounding. All of our
>glasses are etched and look awful too. Dishwashers are hell on dishes. The
>appliance repairman once told me that the powered detergents were abrasive.
>However, we've been using liquid detergents, so I don't think that's the
>cause.
>Hello:
>I have had a query from a customer who is using our maiolica dinnerware on a
>daily basis. She is concerned that her 4 year old maiolica mugs and pasta
>bowls are DULLING on the interior where they come into contact with
>food/beverages. She washes them in the dishwasher with no heat dry, doesn't
>use any abrasives like SOS on surface.
>
>The exterior and rims of the pieces are still as glossy as the day she
>purchased them. Could the dullness be the acidity in the food reacting with
>the dishwasher detergent and causing wear?
>My base glaze is mostly frit 3124 with kaolin and a small amount of flint
>fired to c/04. Look forward to some theories.
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
Cindy Strnad on sun 4 feb 01
Hello, Ron.
I'd be interested in those ^6 Majolica glazes. In addition, if anyone has
such an animal, I'd love some ^3 Majolica glazes. I have a friend who works
in my studio sometimes, and I've laid in quite a store of low-fire clay for
her as she's interested in Majolica and lots of bright colors.
This clay will go to ^3 without bloating, so that's what I'd like to fire it
to. I've been experimenting, but haven't been as successful as I'd hoped in
finding a good Majolica glaze for ^3. Any suggestions?
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Suzanne Jebaily on sun 4 feb 01
I would love to have some of those COne 6 'majolica' recipes you referred to
in a previous post. How can they be obtained?
Suzanne Jebaily
Florence, SC
dayton j grant on mon 5 feb 01
ron roy my name is dayton grant and i would like to know about maijolica
eventually i am overwhelmed right now but that is one of the areas that
interests me as i like to throw earthenware and would like to know how to
properly decorate it
________________________________________________________________
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Ron Roy on tue 6 feb 01
Best three Majolica glazes from a ClayArt project.
All three are opacified with zirconium silicate - some used Zircopax and
some used
Superpax - any zirconium silicate will do although amounts may need to be
adjusted to increase or decrease whiteness and opacity. Tin oxide may also
be used but the amount should be about 1/2 that of the zirconium silicate
to get the same effect. If there is any chrome in any of the colours in the
kiln you can expect pink flashing with Tin.
Stains should be mixed with a glaze - I recommend 1 part stain with three
parts glaze. If the result is too strong then increase the glaze - if too
weak increase the stain, Start with 1 spoon of stain and 3 of glaze . Use
the #4 (Linda's) version #3 without the zirconium silicate (pax.)
Fire all 3 glazes to cone 6 half way down.
I recommend sieving all glazes twice through 80M - taking care to make sure
all material goes through at least once.
****************************************************************************
**********
#4 (Linda Blossom's revision #3 by RR.) Hi CaO - has lowest expansion
(414.51) of all three and will be best on cone 6 porcelains for a good fit.
EPK - 17.0
Silica - 23.0
Neph Sy - 23.0
Frit 3124 - 23.0
Whiting - 14.0
Zircopax - 16.0
Total - 116.0
****************************************************************************
**********
#5 - (Ann Chambers revision #3 by RR) Highest expansion (462.18) of the 3 -
It would be a good idea to try all three on the clays you are going to use
- and decide which glaze to use after testing for fit by freezing and
dipping in boiling water - while still frozen.
Neph Sy - 24.0
Strontium Carb. - 12.0
Silica - 28.0
Whiting - 6.0
Frit 3134 - 15.0
Ball clay - 5.0 (Old mine 4 will work as well as most ball clays.)
EPK - 10.0
Bentonite - 1.0
Pax - 10.0
Total 111.0
Don't shy away from glazes with lots of ingredients - they will be the most
reliable over time.
****************************************************************************
**********
#3 (Ed Brownlee's super white revision #3 by RR) - expansion (461.593) - on
higher side but not as high as #5.
F4 Spar - 54.0
Frit 3134 -15.0
Whiting - 4.0
Talc - 7.0
Ball Clay 20.0 - Most ball clays will work . See below for the same glaze
with EPK
Pax - 16.0
Total - 116
Same glaze but with EPK instead of Ball Clay - (expansion is 450.52).
F4 Spar - 54.0
Frit 3134 -15.0
Whiting - 4.0
Talc - 7.0
EPK - 15.0
Silica - 5.0
Pax - 16.0
Total - 116
It is always wise to test glazes on your own clays in your own kilns before
committing large amounts of time, effort and materials. This type of glaze
has to work in a special way and needs special attention to work well.
Majolica glazes are "stiff' - they must not move when melted because the
colours will not stay where you put them. Stiff glazes can be a problem
because they are so stiff. Pin holes can be a problem. Uneven applications
will not smooth out as in most glazes. Careful firing is required and, in
some cases, these glazes will need some adjustments.
It is important with some types of clays to make sure the bisque firing is
slow enough to remove all carbon and sulphur. I recommend no faster than
100C (200F) per hour and fired to cone 04 in a strictly oxidizing
atmosphere. Slower bisque and glaze firings cure many faults - fast firings
cause many faults.
It is best to let your glazes dry before applying colours. If the surface
is too powdery I recommend adding 1% Bentonite to create a tough surface.
Be aware that some stains and oxides are toxic - it would be best to
minimize the application of colour on surfaces that may come in contact
with food. Remember - the colour in Majolica is applied on top of the glaze
and is therefore much more likely to be affected - especially by acid of
any kind. If you want to use the food bearing surfaces for decoration the
best course of action would be to permanently mark the ware with a warning.
"Not food safe" or "Use only for dry food" or " Colours may be affected by
acids in food." The glazes themselves are good, hard and durable.
You may not give these glazes away without the accompanying instructions
and warnings.
Ron Roy - RR#4, 15084 Little lake Rd. Brighton, Ontario, Canada. K0K 1H0
Fax: 613-475-3513. Home: 475-9544. Email: ronroy@total.net
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
Ron Roy on tue 6 feb 01
Best three Majolica glazes from a ClayArt project.
All three are opacified with zirconium silicate - some used Zircopax and
some used
Superpax - any zirconium silicate will do although amounts may need to be
adjusted to increase or decrease whiteness and opacity. Tin oxide may also
be used but the amount should be about 1/2 that of the zirconium silicate
to get the same effect. If there is any chrome in any of the colours in the
kiln you can expect pink flashing with Tin.
Stains should be mixed with a glaze - I recommend 1 part stain with three
parts glaze. If the result is too strong then increase the glaze - if too
weak increase the stain, Start with 1 spoon of stain and 3 of glaze . Use
the #4 (Linda's) version #3 without the zirconium silicate (pax.)
Fire all 3 glazes to cone 6 half way down.
I recommend sieving all glazes twice through 80M - taking care to make sure
all material goes through at least once.
**************************************************************************
#4 (Linda Blossom's revision #3 by RR.) Hi CaO - has lowest expansion
(414.51) of all three and will be best on cone 6 porcelains for a good fit.
EPK - 17.0
Silica - 23.0
Neph Sy - 23.0
Frit 3124 - 23.0
Whiting - 14.0
Zircopax - 16.0
Total - 116.0
**************************************************************************
#5 - (Ann Chambers revision #3 by RR) Highest expansion (462.18) of the 3 -
It would be a good idea to try all three on the clays you are going to use
- and decide which glaze to use after testing for fit by freezing and
dipping in boiling water - while still frozen.
Neph Sy - 24.0
Strontium Carb. - 12.0
Silica - 28.0
Whiting - 6.0
Frit 3134 - 15.0
Ball clay - 5.0 (Old mine 4 will work as well as most ball clays.)
EPK - 10.0
Bentonite - 1.0
Pax - 10.0
Total 111.0
Don't shy away from glazes with lots of ingredients - they will be the most
reliable over time.
**************************************************************************
#3 (Ed Brownlee's super white revision #3 by RR) - expansion (461.593) - on
higher side but not as high as #5.
F4 Spar - 54.0
Frit 3134 -15.0
Whiting - 4.0
Talc - 7.0
Ball Clay 20.0 - Most ball clays will work . See below for the same glaze
with EPK
Pax - 16.0
Total - 116
Same glaze but with EPK instead of Ball Clay - (expansion is 450.52).
F4 Spar - 54.0
Frit 3134 -15.0
Whiting - 4.0
Talc - 7.0
EPK - 15.0
Silica - 5.0
Pax - 16.0
Total - 116
It is always wise to test glazes on your own clays in your own kilns before
committing large amounts of time, effort and materials. This type of glaze
has to work in a special way and needs special attention to work well.
Majolica glazes are "stiff' - they must not move when melted because the
colours will not stay where you put them. Stiff glazes can be a problem
because they are so stiff. Pin holes can be a problem. Uneven applications
will not smooth out as in most glazes. Careful firing is required and, in
some cases, these glazes will need some adjustments.
It is important with some types of clays to make sure the bisque firing is
slow enough to remove all carbon and sulphur. I recommend no faster than
100C (200F) per hour and fired to cone 04 in a strictly oxidizing
atmosphere. Slower bisque and glaze firings cure many faults - fast firings
cause many faults.
It is best to let your glazes dry before applying colours. If the surface
is too powdery I recommend adding 1% Bentonite to create a tough surface.
Be aware that some stains and oxides are toxic - it would be best to
minimize the application of colour on surfaces that may come in contact
with food. Remember - the colour in Majolica is applied on top of the glaze
and is therefore much more likely to be affected - especially by acid of
any kind. If you want to use the food bearing surfaces for decoration the
best course of action would be to permanently mark the ware with a warning.
"Not food safe" or "Use only for dry food" or " Colours may be affected by
acids in food." The glazes themselves are good, hard and durable.
You may not give these glazes away without the accompanying instructions
and warnings.
Ron Roy - RR#4, 15084 Little lake Rd. Brighton, Ontario, Canada. K0K 1H0
Fax: 613-475-3513. Home: 475-9544. Email: ronroy@total.net
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
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