Glazing Raw Ware

[Birdland]

Hi everyone.  Can I glaze raw ware and then fire it to stoneware temp once it's bone dry?  I'm using stoneware and glazing raw work then firing once up to 1300 celcius and have found the ware shrinks less and it speeds the  up whole process.  Haven't had anything fail (as yet) and am wondering when the disaster I'm expecting is likely to occur.

[Benzine]

It does indeed save time, but you just have to be very cautious, towards the beginning of the firing, because you don't want pieces of exploded glazeware sticking to everything.

 

Beyond that, there are some glazes, that don't turn out well being single fired.

 

There is also the issue of greenware being harder to glaze, becausemof its delicate nature.

 

Do the pros outweigh the cons? That's up to you to decide.

[Mark C.]

(I am wondering when the disaster I'm expecting is likely to occur)

That will be when you got up to fast in the early stages and blow up one pot -it will put small pieces everywhere and ruin lots of work.

Its usually not if but when.

Only you can decied weather its worth it.

Mark

[TJR]

I used to raw glaze all the time. Porcelain is difficult as handles crack off.

I have used both methods;

1.Bone dry

2.Leather hard.

I prefer leathe rhard because there is less shock of expansion and contraction with the work, but you have to adjust your glazes to be more plastic.

Yes, there will be losses and disasters.

TJR.

[perkolator]

as long as you are aware of what you're doing and take the necessary steps to keep the work safe, there is no problem.  not everything will be successful, certain glazes or glaze/clay combo's will not work this way.  this is how we do 90% of the work that gets fired in our sculpture studio, otherwise we'd never get anything accomplished in a 10wk quarter system.  you think some indigenous tribe is would have traditionally fired their ceramics twice, when finding enough fuel to fire once is hard enough to spare?

[oldlady]

been doing this for years.  it is easier to apply the glaze with a sprayer and compressor. do not waste time with small compressors because you will blow them up if you work them too much.

 

 the inexpensive kind, $30 EZ sprayer is easy to clean and if you use many colors you can get bottles pretty cheaply.  just be sure that the bottles are correctly made.  I have some that have almost oval top sections and of course they leak badly.  can't seem to remember to return those da#% things.

[oldlady]

it just occurred to me that I did not mention the most important reason spraying greenware works for single firing.  the glaze is dry to the touch almost immediately.  the pot is never wet like it could be if it is dipped or poured.

 

some folks think that glazes need to be thinned to be sprayed.  not necessarily, all of my glazes are sieved through a 60 mesh sieve.  I know that many think an 80 mesh is needed.  not with the EZ-sprayer.  it is just like the kind with two tubes that you can blow with your own breath except it is powered by an air compressor.   cleaning is simple, I keep a bucket of water nearby and just unscrew the old bottle, dip the end of the tube into water, spray the old color out of the metal parts  and screw a new color bottle on.

 

I had one of those very complicated 56 pieces that had to be washed carefully sprayers.  it is in a pile of other junk in the garage.