Once Fire Glaze For Glazing Greenware - From The Uk?

[jamie shaw]

Hi All,

Does anyone know of a supplier in the UK who stocks a glaze for once firing i.e. it can be applied to dried greenware?

 

I'm planning on adding some stain to earthenware, slipcast a piece, let if dry but not bisque, glaze the greenware and then fire it. I may fire a second time for decal decoration.

 

Any help would be much appreciated.

 

Jamie

 

[ayjay]

If you already have a glaze that works for you and would be right for this project in all other aspects - the simple thing to do is to turn it into a brush-on glaze with the addition of CMC.

[Chilly]

Never seen glazes specifically for once-firing.  I know people who just used the available glaze.

 

Whatever you use, remember the glazing mantra:  Test, Test and Test again.

[ayjay]

Never seen glazes specifically for once-firing. 

 

There are some (recipes). For leather-hard clay you need a high clay content in the glaze to counter the shrinkage of the pot being glazed - without it the glaze is likely to fall off as the pot dries. 

 

For dry clay you need to reduce the water content of the glaze - this is where CMC will help, it doesn't reduce the water so much as prevents it from reaching the pot.

 

If you just dip an unbisqued pot in ordinary glaze it's likely to create cracks at any joins/seams, or possibly just fall apart.

[Marcia Selsor]

you can add 5%bentonite to your glaze to make them work for once fired.

Marcia

[Joe_L]

I've been single firing reasonably successfully using commercial brush-on glazes. I haven't found any explicitly formulated for single firing but generally many seem to do ok. You could always call the manufacturers and ask which of their ranges they would recommend. I'm doing stoneware at cone 9 so can't really suggest a working combination for your situation.

 

In the end you are going to have to run a comprehensive series of tests and work out the right glaze to go with your body/slip AND the right timing and method of application.  I am mostly brushing on dry greenware though I started at leather hard. Experience is beginning to tell me which glazes need watering down slightly or other adjustments, and how many coats etc, but I'm only just beginning to get a glimpse of the picture.

 

Only by doing test tiles and test cylinders (which have curved exterior & interior surface that test tiles don't have) will you discover if the "fit" is right - does the glaze peel or blister as it finished drying, and which glazes pinhole and need and adjustment to firing schedules or timing of application etc. It takes a while but treat it as a fun learning curve.

 

Joe

[Joe_L]

I've been single firing reasonably successfully using commercial brush-on glazes. I haven't found any explicitly formulated for single firing but generally many seem to do ok. You could always call the manufacturers and ask which of their ranges they would recommend. I'm doing stoneware at cone 9 so can't really suggest a working combination for your situation.

 

In the end you are going to have to run a comprehensive series of tests and work out the right glaze to go with your body/slip AND the right timing and method of application.  I am mostly brushing on dry greenware though I started at leather hard. Experience is beginning to tell me which glazes need watering down slightly or other adjustments, and how many coats etc, but I'm only just beginning to get a glimpse of the picture.

 

Only by doing test tiles and test cylinders (which have curved exterior & interior surface that test tiles don't have) will you discover if the "fit" is right - does the glaze peel or blister as it finished drying, and which glazes pinhole and need and adjustment to firing schedules or timing of application etc. It takes a while but treat it as a fun learning curve.

 

Joe

P.S. I do find the colour & texture rendition of glazes changes slightly in single fire compared to bisque. Some glaze/clay combinations exhibit this more than others. I haven't yet worked out whether this is due to thickness (due to how thirsty the body at application time) or interaction with the clay - I suspect both. I would guess that bisqued clay is going to be less reactive.  Another reason for testing!

[rakukuku]

About a million years ago I experimented with once fire glazes on stoneware fired to cone 9. My instructor told me to look for glazes with a high clay content. I think i probably sprayed them on since we didn't have big enough batches to even try to dip would probably wouldn't have worked. Anyway, I got some good results but no clue what the glazes were. But we mixed our own. Since the glaze was applied to a leather hard piece, you could almost tell whether it would work before firing because if the glaze didn't flake off during drying, it usually stuck and worked during firing.

 

Once in awhile I do some tiny things once fired but our kiln tech is reluctant even though it works fine.    gl.  rakuku

[oldlady]

many of you know that i single fire.  my education has been learning on my own.  i use recipes that have been published and given freely by other people and i have absolutely no interest in developing a glaze of "my own".  so i single fire, roll my flat pieces thinner than "normal", throw thin and dry and spray any glaze i have with no regard for the amount of anything in the recipe.  nearly everything works fine.

 

i have very few failures and most are due to something changing or a stupid thing i chose to do.  lots of "what if" questions have been answered that way.  not saying i have any answers but i do think most things are not such enormously frightening events that will bring the end of the world.