Jump to content


Photo

is gilding / gold leafing food safe ?


  • Please log in to reply
32 replies to this topic

#21 jo4550

jo4550

    Advanced Member

  • Members
  • PipPipPip
  • 70 posts
  • LocationAustralia

Posted 04 May 2013 - 09:57 PM

thanks for the link Johanna! Posted Image

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.westernsa...newnorth1.html"



Regards
Johanna

#22 kennedy james

kennedy james

    Advanced Member

  • Members
  • PipPipPip
  • 39 posts

Posted 07 May 2013 - 07:22 PM

thanks for the link! tons of useful info in there :)

#23 Debra

Debra

    Newbie

  • Members
  • Pip
  • 3 posts

Posted 08 September 2013 - 09:04 PM

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...



#24 kennedy james

kennedy james

    Advanced Member

  • Members
  • PipPipPip
  • 39 posts

Posted 17 April 2014 - 01:51 PM

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 ??



#25 kennedy james

kennedy james

    Advanced Member

  • Members
  • PipPipPip
  • 39 posts

Posted 19 April 2014 - 10:49 AM

anyone ??



#26 Tyler Miller

Tyler Miller

    Advanced Member

  • Members
  • PipPipPip
  • 270 posts
  • LocationOntario, Canada

Posted 19 April 2014 - 11:01 AM

I think you might have sailed into some unexplored territory. I have a lustre kicking around, but I've never used it.  Beyond contacting the lustre manufacturer and the glaze manufacturer about what to do, I think experimentation or research might be in order--to me, the best and worst parts of the ceramics game. :)



#27 kennedy james

kennedy james

    Advanced Member

  • Members
  • PipPipPip
  • 39 posts

Posted 19 April 2014 - 11:03 AM

is it normal for a high fire glaze to change so much at 06 ? I fired it a cone 6 

 

I'm really surprised it had so much effect on it...



#28 Denice

Denice

    Advanced Member

  • Members
  • PipPipPip
  • 646 posts
  • LocationWichita, Kansas

Posted 19 April 2014 - 11:22 AM

Yes it is normal glazes to change when refired to a lower cone, I tested a bunch of formula's from Ceramics Monthly that were meant to be refired.  They were quite ugly at C6 and were beautiful when refired at C04.    Denice



#29 kennedy james

kennedy james

    Advanced Member

  • Members
  • PipPipPip
  • 39 posts

Posted 19 April 2014 - 11:23 AM

interesting! thanks for the reply



#30 JBaymore

JBaymore

    Moderator

  • Moderators
  • 2,808 posts
  • LocationWilton, NH USA

Posted 19 April 2014 - 11:28 AM

I do a lot of china paint and luster work on my woodfired pieces. Yes, they can change ...sometimes a lot (but they all don't).  One of my shinos gets dramatically better.

 

I never try to "burn out" screwed up gold luster. Try to get it 100% before it gets to the kiln. Fix it (if needed) before it is fired. Including total removal (expensive). If it is not something that can be helped by adding a bit more (like a skip) on a refire, I usually just trash the unsucessful piece. Usually... such mistakes repairs show when you try to repair them...... thereby affecting quality.

 

best,

 

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


John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#31 jo4550

jo4550

    Advanced Member

  • Members
  • PipPipPip
  • 70 posts
  • LocationAustralia

Posted 19 April 2014 - 06:56 PM

Hello Kennedy

It is normal for some glazes to change on a refire especially when you are approaching the softening point (I do not mean melting point) of the glaze.  This is the point where the fluxes start to be active.   This has become very obvious when running the laser decal classes and searching for the softening point for the decal to adhere.   There is a fine line where the glaze doesn't react and this is at the lower end of the temp scale.   I would hazard a guess that your glaze has a flux that has a very wide firing range and it is perhaps Gerstly Borate.  You seem to have reached a point at cone 06 in your glaze where the glaze is already outgassing and the cooling at 06 halts the process and and traps the gases changing both the colour and the integrity of the glaze.   

 

To resurrect this glaze AND burn off the lustre find a cool spot in your glaze firing and take back up to top temp.   This should restore the glaze.  I say cool spot as refiring is almost like going a cone higher than the original firing.

 

I would have attempted to save the gold and platinum surfaces by adding a couple more layers (with firings in between) and firing to your gold firing temperature before I took the drastic step of burning the lustre off.  To remove small areas of lustre it is common to use a gold eraser but it has to be used carefully as you can "matte" the surface of the glaze that you are rubbing.  Lustre can also be removed by using hydrofluoric acid but I personally wouldn't go down that path for H&S reasons.  It also mattes the surface of the glaze where the lustre has been removed.

 

Cheers

Johanna



#32 JBaymore

JBaymore

    Moderator

  • Moderators
  • 2,808 posts
  • LocationWilton, NH USA

Posted 19 April 2014 - 07:24 PM

Kennedy, you just heard from THE person to listen to here when it comes to lusters and overglazes! Check out her work.

 

Johanna...... thanks for sharing your expertise here on the CAD forums.

 

best,

 

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


John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#33 kennedy james

kennedy james

    Advanced Member

  • Members
  • PipPipPip
  • 39 posts

Posted 20 April 2014 - 11:40 AM

 

I would have attempted to save the gold and platinum surfaces by adding a couple more layers (with firings in between) and firing to your gold firing temperature before I took the drastic step of burning the lustre off.  To remove small areas of lustre it is common to use a gold eraser but it has to be used carefully as you can "matte" the surface of the glaze that you are rubbing.  Lustre can also be removed by using hydrofluoric acid but I personally wouldn't go down that path for H&S reasons.  It also mattes the surface of the glaze where the lustre has been removed.

 

Cheers

Johanna

 

I did add a layer to the silver cup. the cup I try to burn off the luster from was another test, I only wanted to burn it off because some of the luster went on the top where I dont want any... I thought I cleaned everything but the glaze being black it's very hard to see if there is any luster where I don't want it. 

next time I will use a luster eraser if I can find one at my ceramic shop. 

 

thanks for your answers Johanna !






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users