What Do You Do If Commercial Glaze Runs Excessively?
Posted 04 October 2010 - 02:45 PM
Posted 05 October 2010 - 10:14 PM
You could do some test tiles or test cups and glaze them at varying points/thicknesses and try to measure how far the glaze runs and then take that into consideration when using the glaze. You could also try a thinner glaze application on the lower 1/3 of the item and see if that affects the running. But if its a runner, I tend to avoid it -- I have better things to do than scrape kiln shelves. With commercial glazes, its almost always a case of trial and error.
Posted 06 October 2010 - 08:30 AM
Posted 06 October 2010 - 02:38 PM
Yes, of course they are and I understand the obvious... fire to a lower cone. However, for me that isn't viable since most of my firings are made up of pieces decorated with a variety of glazes that fire as desired at cone 5. Certainly, many glazes need to run a little to properly break and develop their characteristic look... I'm not talking about those... I'm referring to the ones that drip onto the kiln shelf (even when thinly applied) if they're within an inch of the bottom of the pot.
Running glazes are always a result of over-firing.
My specific question was if/how others may have successfully adjusted the chemistry of a runny commercial glazes to raise its melting point slightly w/o significantly affecting the glaze. I would think adding a little silica would raise the melt point, for example.
Posted 07 October 2010 - 10:35 AM
So, use com glazes untill you can find or create a glaze that will replace it.
Posted 11 December 2010 - 05:26 AM
... or do you adjust them slightly to raise/lower their melting point slightly? What approach have you found works best?
I was faced with a vast quantity of running glaze when I did a locum at an art centre where the users didn't know they had to stir all the way to the bottom of the bucket. I stirred what was left properly, measured out half a litre of slop, sieved 5g of flint and 5g of china clay into it. (This was a stab at getting somewhere close to 5% of dry ingredients). Was ready to try 20g per litre if necessary but the first stab at it worked a treat.
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