my pseudo-mosaic...some newbie questions

[sugarbeth]

Hello clay people! Thought I'd give this message board a try, as the clayart forum's technology is frustratingly old-fashioned for me.

I'm making a pseudo-mosaic for my master bathroom mirror. You can see it in my blog here:

I'd like to fire to the upper temp of the clay to make the tiles as vitreous as they'll go, but underglazes are typically fired to 06.

What do people usually do? Bisque at 04 then glaze at 1? Or bisque high and then do the glaze firing at 06? Does it even work that way?

I'm doing lots of test tiles beforehand, but I thought I'd get some input. Thanks!

Beth

[imported_aclift]

Hi there,
Thanks for joiinng the group! So far its pretty much just me answering questions. :? I created this group mainly because of the reason you joined. And also to focus strictly on technical topics. This group is in its infancy but it is starting to grow much more rapidly lately, so it should work out just fine.

Anyway lets get to your question. I am using commercial underglazes these days quite a bit. I use Vevelt underglazes by AMOCO. I fire to cone six even though they tell you to fire them to 06 on the directions. So they most certainly should be fine at cone 1.

Many underglazes by other manfuactures should also fire to at least cone 1 as well. Although you may find that 1 or 2 colors burn out so you really have to test the underglazes first to see if they do all right at cone 1.

You could try firing either of the two ways you mention. But generally potters or ceramic artists bisque fire to 06 or 04 and then do their glaze firing to the glaze maturing temp. Mainly because it will be much easier to apply the glaze or underglaze to a porous surface.

In more of a commercial/production situation they would fire first to vetrify the clay and then do a glaze firing at a lower temp. Many of them heat and spray glazes on so they can get a glaze thickness that will be safe and durable enough.

Good luck! I'd be happy to help with any follow up questions.
Andy

[sugarbeth]

Thanks, Andy! That really helps.

I'll be figuring out my color palette and running my tests this week.

[sugarbeth]

I've been running lots of tests lately!

Looks like all my colors are fine to cone 1. I'm using Mayco's stroke'n'coats. Some colors seem more translucent, and some more opaque. Not sure yet whether it's a temperature thing, or an underglaze thing...I just went up to the high temp from the beginning. Or maybe the translucent ones needed a bit more mixing or something (the bottle is so full, I'm sure they're not getting mixed all the way).

My new issue is that my clay, which is labeled 06-1, is still really porous at cone 1. I just fired some more tests taking it all the way to 3, and the tiles are finally looking more vitreous now.

Is this typical of how clay is labeled? I was assuming it would be vitreous at cone 1, since that is the high end that it's labeled at, but maybe not?

I think the colors will be okay at 3, but I'm starting to wonder if I should take the path where I vitrify the clay first. ???? Thanks in advance!