Crystalline Glaze Firing Program

[Shelly M]

Hello all,

I'm not having great success getting crystals to form when firing. I've tried several crystalline glazes from Mayco and Coyote. I have an electric kiln and currently use a cone 6 program with 5 ramps. The top  temperature is 2175F with a 15 minute hold. Then on the way down: 500F/hour to 1900 with no hold then 150/hour to 1450F.  The kiln then cools down naturally to room temperature. Any suggestions? 

Thanks for your feedback and advice

[glazenerd]

Shelley:

I fire macro-crystalline glaze: but have no experience with commercial premix. Do you have links I can read on these products?  Will take a look and see what's applicable.

Tom

 

[Min]

@Shelly M, I could find info for the Coyote Crystalline slow cool glazes but for Mayco I could just fine their Jungle Jems and Crystalites which are not true crystalline glazes. For the Coyote ones their recommended firing schedule is a bit different than yours:

"Ramps 5
100/hr to 220
350/hr to 2000
150/hr to 2200 hold for 15 minutes
500/hr to 2150 hold for 15 minutes
125/hr to 1400

It is important to note that you will need to tweak this schedule for your own kiln and firings.  Every kiln is different, so there is no schedule that will work for every firing.
The tip of your self supporting cone 5 should be at least even with the base, and the tip of the cone 6 should not touch the shelf."

Re the Mayco ones, these are not glazes that form crystals in the same manner as the Coyote ones. Mayco uses little chips / tiny bits of another glaze that has been sintered then added to the base glaze which then melt into the base while firing. These little bits can sink in the bottle of glaze so it might just be an issue of needing more thorough mixing prior to application.

[Shelly M]

16 hours ago, Min said:

@Shelly M, I could find info for the Coyote Crystalline slow cool glazes but for Mayco I could just fine their Jungle Jems and Crystalites which are not true crystalline glazes. For the Coyote ones their recommended firing schedule is a bit different than yours:

"Ramps 5
100/hr to 220
350/hr to 2000
150/hr to 2200 hold for 15 minutes
500/hr to 2150 hold for 15 minutes
125/hr to 1400

It is important to note that you will need to tweak this schedule for your own kiln and firings.  Every kiln is different, so there is no schedule that will work for every firing.
The tip of your self supporting cone 5 should be at least even with the base, and the tip of the cone 6 should not touch the shelf."

Re the Mayco ones, these are not glazes that form crystals in the same manner as the Coyote ones. Mayco uses little chips / tiny bits of another glaze that has been sintered then added to the base glaze which then melt into the base while firing. These little bits can sink in the bottle of glaze so it might just be an issue of needing more thorough mixing prior to application.

Thank you Min! I'll look at my schedule again and give it another go. I have a glaze called "Robin's Egg" from Mayco. Not sure why they don't have info on firing this glaze. It turned our very matte and none of the crystals melted despite the fact my cone's were bent just as Coyote describes. But each company is different so I'll reach out to Mayco. Thank you for taking the time to research.