Jump to content
mrcasey

What is the purpose of overglaze?

Recommended Posts

I recently found an old abandoned box of standard overglazes in our studio closet.  We only fire to cone 05 and 6 electric.   My understanding is that these overglazes are applied

after the glaze firing and then fired to a very low temperature.  The info on the containers is kind of vague about cone temperature and application.  The digital fire pages says that

some overglazes or onglazes are fluxed with bismuth and will melt at around 1300F!  Maybe I could use them in pit firing?  Can anybody tell me a little more about these "overglazes"

and how/why someone might want to use them.                       

Share this post


Link to post
Share on other sites

I use on glaze.... Majolica glaze plus onglaze dec. I decorate on unfired glaze surface to cone 5/6.

Low firing ...raku as pit firing unless in a saggar will be a mess imo

Share this post


Link to post
Share on other sites

On glaze, or in glaze is the process of using underglazes or over glazes on an in-fired glazed surface. All so often, the quality of the in-glaze decoration is dependent on the base glaze which is usually white. If the base glaze has zinc as an opacifier, it will have a tendency to dull some of the colors over top like copper greens and some cobalt blues.  Another problem could be tin used as an opacifier where chromium and tin will together can cause flashing of a red/pink color on other parts of the pot or even other pots in the kiln. That is one of the reason many of us have resorted to using titanium, zircopax  or superpax  or even a combination of zircopax and tin or some other opacifier for the white base. I personally have found that zircopax for me is not a nice white without some softening. 

Over the years, I have found my most exciting attempts at surface have come from a combination of dipping, spraying and brushing. Usually in that order. I also have found that these techniques allow me to create texture and pattern whether spraying through stencils, or spraying from different angles over the stamped or engraved clay surface.

 

best,

Pres

Share this post


Link to post
Share on other sites

mrcasey,  have you seen the painted plates and other dinnerware that was done about 1900 by "ladies"?    the beautiful full blown, pastel roses that look like a watercolor painting are the ones that come to mind.   they were done with overglaze.    if you look at amazon books for China painting, you can see some really good info, there is a prediction that it is coming back into fashion.

not being a real "lady" that is all i know.   

Edited by oldlady
add

Share this post


Link to post
Share on other sites

By overglazes are you referring to little bottles of powders or liquids? Overglazes or china paints can come as a dry powder or already mixed up with a brushing medium. The dry sort need to be mixed with either an oil  or water based brushing medium or just plain water, personal preference. Everything, including the pre glaze fired pots has to be scrupulously clean, wipe down the pot with rubbing alcohol, wear gloves so you don’t leave fingerprints. If you are using metallic overglazes wear a P100 respirator, work in a well ventilated area, outside if you can, and when you are finished lauder your clothes and take a shower. China paints / overglazes fired in the 020 - 018 range, well vented kiln for the metallics especially.

Could you post a picture of what you have and someone might be able to give more detailed help. 

Edited by Min
clarity

Share this post


Link to post
Share on other sites

coincidences happen!   a friend gave me some old magazines and i looked at one this morning.  it was "Clay Times" from sept/oct  2002 and the cover photo was a white porcelain bottle by Sam Scott showing his overglaze technique.  

he is working differently now but if you google his name followed by pottery, some of the older work comes up.  his recipe for the colors he uses are for oxides, not whatever you have found. 

overglaze can be much more than i originally thought.

Edited by oldlady

Share this post


Link to post
Share on other sites

I was thinking that on glaze and overglaze as synonymous.

Then enamels , lacquer china painting as a third firing process at a much lower teml.

As mim says. More details on product or run a few test tiles may give you an insight into how you can use them or not..

Share this post


Link to post
Share on other sites

1lb is an awful lot if infactt t is an enamel or china paint.

I think you have a colourant to be used on unfired glaze or bisqued unglaze imo but testing would get results.

Bismuth, bit toxic...

Share this post


Link to post
Share on other sites

I suspect that this stuff was never actually used in our studio.  I further suspect that it was taken from a local community college's larders when their

ceramic art program was shut down.            

Share this post


Link to post
Share on other sites

I remember the packaging, this was probably 15 years ago or more. They did make an overglaze material, and it was fired to a lower temp over a pre-fired glazed piece. SC has gotten out of most of these glaze products preferring to use 3 rd party manufacturers it seems.

 

My humble opinion,

best,

Pres

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.