Expert: Ti Phillips - 10/12/2009

Question
My mum and I run a paint your own pottery business. Recently, some of the items we have fired have come out with a milky look to the clear dipping glaze. We watered it down a bit as we were half way down a 5 gallon tub. Some items have come out with no problems yet others still have a milky appearance. It is also not milky all over but just on certain areas. Refiring doesn't seem to help either. We are completely confused as to why this is happening. Please help.

Answer
Dear Ms Kidd,

    Thank you for your recent question. Clear glaze that turns milky is cause from either applying the glaze too thickly or not firing hot enough. The first thing I would check is the glaze itself. Since you watered down the glaze some, it may be that the glaze is not mixed adequately. If the glaze particles are not suspended in the water, then what you will be applying to the pottery is water, with a bit of glaze particles in it. Because you are using a 5 gallon bucket, use a jiffy mixer on a drill to adequately mix the glaze prior to applying.

    If this doesn't work, the next step is to check the application method. Made sure the glaze is being applied evenly when dipped. Allow the glaze to flow off the pot after holding for the count of 3. Once the glaze has stopped dripping, then you can set the pot on it's bottom to dry.

    Finally, if the problem isn't resolved, check your kiln. It may not be firing hot enough. This will cause a glaze to milk. If you wish to save the pieces that came out with the milky look, refire to one cone hotter, but only if the kiln is having problems reaching the proper cone maturing temperature.

    I hope this helps you. If you have further questions, please let me know. Let me know the outcome of the solutions I gave you. Good luck!

Sincerely,
Ti Phillips
Earth Stoke 'N Fire Pottery Studio and Artist Retreat
www.earthstokenfire.com