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kennedy james

is gilding / gold leafing food safe ?

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Hi everybody!

 

I'm a newbie at ceramic, and I have a project of porcelain sake cup of which the inside would be golden.

 

but after some googling I found out that gold luster is not food safe, but I've been seeing a lot of drink and food vessels with a golden inside.

 

for instance:

 

http://www.flickr.co...shades/2679339/

http://www.nousaku.c...le1/51160-1.jpg

http://kutani.wordpr...-color-guinomi/

http://www.flickr.co...otos/1634773964

http://www.lennekewi...sssakelogoS.jpg

http://1.bp.blogspot...n_Gold_Bowl.jpg

 

so I'm starting to think that gold leafing could be food/drink safe unlike the gold luster ? is it true ? I could not find much information about it

 

but some of the pieces don't seem to be gold leafed as it look more like a glaze... I'm a bit confused about that...

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Dinah    6

I had similar questions and got involved in a bit more research than you seemed to have done. I contacted johanna.demaine.org who was extremely generous with her time and information. I just kept on researching images of potters who use gold in their work. Following from < to > a quote from Demaine's reply to me follows. <1. Rosenthal uses gold lavishly on rims of domestic glass and pots and the EEC has the most stringent guidelines for ceramics production in the world. 2. For those of us who can afford it, dentist [sic] still use gold for fillings. 3. Gold powder/flakes are sprinkled on food and eaten.>

 

Gold leaf is used on the inside lid of carved ivory (Oh. Please. Don't start an elephants/walri/unicorns are slaughtered needlessly thread, and frankly if the vast warehouses of confiscated ivory could sell it all off, illegal poaching might come to a temporary closure. Might....) tea caddies -- to muffle the tink sound of the lid, so as to not disturb the flow/moment in Tea Ceremony. Many, many potters use gold leaf on the inside of tea bowls and sake cups. Resinate gold, or platinum luster features in much of my current work. Have a look at Ueba Sasumi's work. You would do well to have a look at the various styles and shapes of both tea bowls and sake cups to see which shape seems to encourage various decorative techniques. Some outside techniques would never consider a gold interior. Talk to Johanna. Be humble. Her work is incredible. She walks the walk, and talks the talks with the gold issues.

 

Enjoy your area of exploration! Many reading this thread would adore having the time and space, inclination, talent, techniques to follow your thread towards a body of work. Please do continue to share your explorations and images of progress on this forum. Always available to help. And I know many others will chime in with their take on this topic.

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JBaymore    1,432
Gold leaf is used on the inside lid of carved ivory (Oh. Please. Don't start an elephants/walri/unicorns are slaughtered needlessly thread, and frankly if the vast warehouses of confiscated ivory could sell it all off, illegal poaching might come to a temporary closure. Might....) tea caddies -- to muffle the tink sound of the lid, so as to not disturb the flow/moment in Tea Ceremony.

 

 

The use of gold foil on the interior of the ivory chaire (tea caddy) lids actually is based in tradition coming from centuries past. It is related to detecting poison mixed into the matcha in the violent times in which much of Chanoyu (Tea Ceremony) traditions and practices were refined. The poisions typically in use in those days would cause the gold to change color.... indications that your life was in imminent danger.

 

This initially highly functional tradition has been passed down into modern Chado (Way of Tea) as a ritualistic part of the practice.

 

best,

 

...............john

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The use of gold foil on the interior of the ivory chaire (tea caddy) lids actually is based in tradition coming from centuries past. It is related to detecting poison mixed into the matcha in the violent times in which much of Chanoyu (Tea Ceremony) traditions and practices were refined. The poisions typically in use in those days would cause the gold to change color.... indications that your life was in imminent danger.

 

 

that's very interesting !

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neilestrick    1,379

Raw gold, gold leaf and gold luster are three different things. Leaf is applied with an adhesive which may have food safety issues, and luster is fired on, which may also have food safety issues. Research thoroughly.

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jo4550    11

Raw gold, gold leaf and gold luster are three different things. Leaf is applied with an adhesive which may have food safety issues, and luster is fired on, which may also have food safety issues. Research thoroughly.

 

 

Hello Neil

Genuine gold leaf can be fired onto the surface of the fired glaze. Imitation gold leaf can't. Some research will corroborate this.

 

Johanna

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JBaymore    1,432

Genuine gold leaf can be fired onto the surface of the fired glaze.

 

The Japanese frequently use this technique.

 

best,

 

...............john

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jo4550    11

name='dontstareatthesun' date='17 January 2013 - 09:53 AM' timestamp='1358380420' post='27980']

Genuine gold leaf can be fired onto the surface of the fired glaze.

The Japanese frequently use this technique.

 

 

and that would be food/drink safe ?

 

 

Hello Kennedy

 

Gold for use in ceramics comes in the following forms:

1. Powder

2. Leaf

3. Liquid as Liquid Bright Gold (different concentrations) and Burnishing Gold.

 

I have attached a PDF of the relevant section of Kenneth Shaw's "Ceramic Colors and Pottery Decoration" This will explain to you all that is known about gold and ceramics.

And yes, fired gold leaf is food safe.

 

I beg to differ with your initial statement that "but after some googling I found out that gold luster is not food safe" I would be interested in viewing your links on this. The other attached PDFs should settle your mind about the food safety of gold as well.

 

Below is an edited copy of an email reply that I sent to Dinah Snipes Steveni in July 2012 after she contacted me regarding gold and food safety.

"My first thoughts when I read this are:

 

  1. Rosenthal uses Liquid Bright Gold and Burnishing gold lavishly on rims of domestic glass and pots and the EEC has the most stringent guidelines for ceramics production in the world.
  2. For those of us who can afford it, dentist still use gold for fillings
  3. Gold powder/flakes are sprinkled on the food and eaten.

 

Gold is a pure base metal and it is used in overglaze by extracting the salt of the metal through the use of aqueous regis. For LB (Liquid Bright) and burnishing gold it is then modified by adding mediums and solvents to facilitate its application. These burn off during the firing leaving the pure gold attached to the surface of the pot around 800.C depending on the glaze type being used. Gold itself melts at approx. 1060.C and starts to vapourize. Gold is also used as a powder and paste. I have attached 4 PDFs showing the use of gold, the MSDS and CAS# readings to interpret the MSDS. I get my gold from Fay Good (http://interdec-australia.com.au) and I am pretty sure they source their gold from Heraeus in Germany.

 

You will see from the Fay Good MSDS that all components bar the gold resinate are either mediums or solvents. You can check their MSDS through CAS#. They all burn out, though I must say it is pretty toxic to breathe in the fumes during the firing. After 450.C all seems to burn out and you can breathe the air again around the kiln.

 

The hysteria that surrounds the leaching with potters is that they don't do the research to fully understand what is going on. The main culprit with leaching is that lead is used as a flux for lower temperatures. If a glaze is properly constituted and fired to its optimum temperature it will not leach but there are too many variables with individuals and companies taking short cuts so that the use of lead frits has been regulated and lead oxide has been banned in the EEC ceramics industry. However many potters don't realize that once the kiln is contaminated with lead fumes it will be contaminated for a long time.

 

I must point out here that neither gold nor lustres have any lead in their formulation.

 

With the perceived leaching problems with Overglaze colours potters don't take the trouble to find out all the facts. Overglaze colours(commonly known as China Paints) are in fact just a very low firing glaze. In the past these have been based on lead as the main flux. Because people (both potters and decorators) are notorious for picking their own firing temperature instead of the maximum recommended, the lead is not always locked in. Now regulations have been brought in by the EEC that ware cannot have more than the allowable level of lead in the decoration from where it touches food or liquid so a whole lot of research has been done to find alternatives for lead as a low firing flux. They are now using a boron based flux. I don't know whether that has happened yet in the US. However in China they are still using lead so be careful when buying any overglaze colour that you can't verify its source. If it is not in contact with food then there is no problem in the fired state. The problem lies in its powdered state. Don't smoke and take care with the dust and also food in the studio. Don't lick or chew the brush which surprisingly a good few people do.

 

Another thought that passes through my mind is that gold is really expensive and the price of the work should reflect this. Why would a potter then expect that a piece with a gold interior should be used? It is easily abraded. For me gold is used to make a statement. It is like the icing on a cake. However if you cut the cake you destroy the icing.

 

Reading back through this I sense that this sounds very much like a lecture. I can assure you that it isn't. I just get very passionate about all the misinformation that floats around today. I see this as a result of everybody wanting to be seen as an artist without having any basic training or taking the trouble to acquaint themselves with the knowledge about what they are using. Everybody is trying to reinvent the wheel for their own ends but sadly without knowledge the wheels are turning out square."

 

As I seem to have run out of upload space here is the link for the Heraeus PDF on the use of gold on dinnerware. http://heraeus-preci...china_home.aspx

 

Regards

 

Johanna

 

 

Gold.pdf

CAS 7440-57-5%20%20 GOLD.html

MSDS Liquid Bright Gold.pdf

Gold.pdf

CAS 7440-57-5%20%20 GOLD.html

MSDS Liquid Bright Gold.pdf

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JBaymore    1,432
The hysteria that surrounds the leaching with potters is that they don't do the research to fully understand what is going on.

 

BINGO!!!!!!!

 

best,

 

.............john

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JBaymore    1,432

Genuine gold leaf can be fired onto the surface of the fired glaze.

The Japanese frequently use this technique.

 

 

and that would be food/drink safe ?

 

 

As Johanna has so eloquently said...... yes. Just not very duirable in day-to-day use. The Japanese tend to treat the handling of really fine ceramics in a manner that is much diferent from whcyt most westerners do... so the durability is usually not an issue.

 

best,

 

.............john

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thanks for all the information Johanna, it is really helpful!!

 

I do not remember where on the internet I found people/articles saying that gold lustre was not food safe, but I got it confirmed by the manager at theceramicshop.com when I went pick up supply last time...

 

now what about kilns contaminated with lead fumes ? does that mean every time you'll fire a piece it will get contaminated and turn it not food safe ?

 

I do not have a kiln of my own and will surly use the ones at the Ceramic Shop, so I'm concerned about any contamination and its repercussions...

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The Japanese tend to treat the handling of really fine ceramics in a manner that is much diferent from whcyt most westerners do... so the durability is usually not an issue.

 

 

do you know how they would handle fine ceramics ? I would be interested to know...

 

I'm guessing westerners would tend to scrub anything, resulting of the gold fading ?

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JBaymore    1,432

The Japanese tend to treat the handling of really fine ceramics in a manner that is much diferent from whcyt most westerners do... so the durability is usually not an issue.

 

 

do you know how they would handle fine ceramics ? I would be interested to know...

 

I'm guessing westerners would tend to scrub anything, resulting of the gold fading ?

 

 

Good ceramic works in Japan are VERY highly respected and highly valued. Careful handling and cleaning are routine with such pieces. Certain types are routinely stored in cloth coverings and or cloth bags, and then in wooden boxes sized to fit the works.

 

Pieces that in the west might go into display cases.... are often used in Japan. May times I have eaten using things like Shimaoka Tatsuzo plates and Hamada Shoji bowls. Very old Ido chawan from Korea are used in Tea Ceremony. And so on.

 

When handling things like Chawan (teabowls) and chaire (tea caddies) and other Chadogu (tea ceremony wares) they are held close to the soft tatami mat flooring, things like rings and bracelets are taken off... and so on. XCleanuing is done very carefully with non abrasive materials. When you are handling a $1000 plate or a $7000 chawan.... you are careful.

 

best,

 

..............john

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JBaymore    1,432
now what about kilns contaminated with lead fumes ? does that mean every time you'll fire a piece it will get contaminated and turn it not food safe ?

 

Potentially yes.

 

The more lead glazes the kiln has fired, the greater the depositing of lead fumes into the refractories. Hence every time it is fired, the lead continues to fume... and deposits onm the surface of the cooling wares.

 

The only way to know is to test the refractories with a lead test kit... and then is positive ... also a representative sample of the fired wares done in that kiln.

 

best,

 

...............john

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I'ven't been able to work on my project until recently, I'm currently working on the plaster mold and I will post pictures as soon as I produce my first piece! :)

 

I've been searching online for Gold Lusters and found that Duncan was pretty much the only one available in many shops online (or at my ceramic shop).

 

as I intend to use it, I wrote to Duncan to make sure it was lead free and food safe and it is:

 

 

"Dinnerware Safety: Overglazes can be used on surfaces that come into contact with food and drink. Care must be taken to avoid hard scrubbing when washing overglazed ware, because of the possibility of scraping o the thin layer of metal or luster. Treat your overglazed pieces as you would ne china. Although overglazed ware will take repeated washings in a dishwasher, the overglaze will eventually wear away.

Note: Ware decorated with metallic overglazes should not be used in microwave ovens."

 

now, I remember that when I went to my ceramic shop and inquired about Duncan gold luster they told me it was not food safe at all and that I should use the Palladium Potter's Choice glaze instead because this was food safe. I liked this glazed very much and I was planning and trying it too but then I checked on Amaco website and Palladium is the only glaze from the PC collection that is not food safe !!! haha this is quite comical that the ceramic shop manager recommended me to use something actually not food safe because she is convinced that Duncan Luster is not food safe.

 

I guess it's a good thing that I am such a data/info freak wink.gif

 

that said, is there some other brand other than Duncan that you would recommend and that I could find online ?

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jo4550    11

http://chinapaintingtoday.com/store Look under Precious metals. I can recommend the Fay Good 12% liquid bright gold. It is a German product. It is the one I use. Another link to gold is

http://www.thegoodstuff.com/ghlb1.html. This is also a German product. Germany has a history of producing the best gold.

 

Golds and lustres are best bought from China/Porcelain painting suppliers. I don't know of too many painters who use Duncan products. They are aimed more at the hobby market.

 

Regards

Johanna

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thanks for the link Johanna! smile.gif

 

also, would you recommend a respirator ? I searched for paint respirator on the 3M website ( http://bit.ly/10yLzPU ) but I'm not sure which one to go with...

 

EDIT: I think I will go for the 3M 6100 half piece mask with the P100 Particulate filter when handling plaster and 6001 Organic Vapor filter when working with luster/china paint

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jo4550    11

thanks for the link Johanna! smile.gif

 

also, would you recommend a respirator ? I searched for paint respirator on the 3M website ( http://bit.ly/10yLzPU ) but I'm not sure which one to go with...

 

EDIT: I think I will go for the 3M 6100 half piece mask with the P100 Particulate filter when handling plaster and 6001 Organic Vapor filter when working with luster/china paint

 

Hi Kennedy

You seem to be on the right track with your choice. Here is an extract from an article I wrote called "Health and Safety and Overglaze (in paticular lustres)" which is reprinted here on my website http://overglaze.dem...rg/?page_id=460

 

 

"My method of protection from fumes is as follows. I use a fume booth constructed by my husband together with a respirator while I have developed a method of working that limits my exposure to the hazards involved. I use a resist method whereby I estimate that 90% of my time is spent using lustre resist which is quite inert. The other 10% is the actual application of the lustre, as all the fine lines apart from some gold pen work is achieved by resist. I am confident that I am limiting my exposure to lustre.

As well as this I wear a respirator. It is a Norton brand 7700 series silicone half face mask model with 2 N7500-1 organic vapour cartridges. It is extremely comfortable to wear despite the fact that I wear glasses. These cartridges are not suitable for clay dust etc. For that you need a particulate filter. However it is not enough to just wear the respirator. It must be maintained. When you have finished using it the inside must be wiped and then the whole lot stored in a sealed (clip lock) bag). This extends the life of the cartridges and keeps dust out. The cartridges need to be replaced when fumes can be smelled through the respirator. Norton has recently been taken over by North Safety Products. A web link to view is http://www.westernsafety.com/newnorthrespirators/newnorth1.html"

 

Regards

Johanna

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Debra    0

Hello!  I've read through this page with interest.  My question is very specific...  I have an old china tea set whose pot has some worn gilding.  I thought that the gilding was put on after the firing, but it sounds like it was fired on, and therefore it would be unwise to attempt any sort of repair.  Is this correct?  Thanks for any advice...

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I did my first luster tests a few days ago. I actually fired them twice to retouch them a little... I might fire again because the silver one is not fully covered at the bottom.. or I'll just try to make new tests and learn how to handle lusters more.

 

the gold is a bit cloudy at the bottom... 

 

13890819032_27547b02b8_c.jpg

 

I messed one of my test cups and got luster on the top, I was sure I cleaned everything though, but I guess doing luster on black glaze makes it harder to clean up...

 

I'm using Duncan lusters and they say to fire at cone 06 to get the luster off, but that didn't work for me, the gold luster only partly disappeared and the black glaze turned bubbly and cloudy :(

 

13913993603_cbeb49919c.jpg13913934615_5fb3095cb3.jpg

 

any tip on firing off luster without messing the glaze ??

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