Mayco raku glazes in electric kiln?

[semidoomed]

Hi everyone,

A student of mine bought a couple of Mayco raku glazes and wanted to see if she could use them in our studio. We use cone 6 clay (BMIX) here but bisque fire it to 04. I was reading the instructions on the raku glazes and it says that it can be fired to around 04 followed by the raku process. My question is: can we safely fire the raku glazes onto our clay and only fire it to 04 without having to follow through with the rest of the raku firing process since my studio doesn't do raku firings? She is only making sculptural work so I'm not worried about firing the clay fully to cone 6. 

Thanks in advance! 

[Kelly in AK]

Do some test tiles and put them on a cookie. A tile (or sacrificial piece) with a large vertical surface will help you interpret how the glaze runs. The only problems I foresee are a runny glaze that goes all over the shelves and an uninteresting result. A lot of raku glazes are specifically designed to become interesting on being thrown into a trash can full of straw, red hot.

“Around cone 04” sounds a little vague. I would trust what the label says, no more, no less. Mayco is not exactly a fly by night operation. It does seem like they say cone 06 is the target for these glazes. Prepare for runs at 04. 

[semidoomed]

16 hours ago, Kelly in AK said:

Do some test tiles and put them on a cookie. A tile (or sacrificial piece) with a large vertical surface will help you interpret how the glaze runs. The only problems I foresee are a runny glaze that goes all over the shelves and an uninteresting result. A lot of raku glazes are specifically designed to become interesting on being thrown into a trash can full of straw, red hot.

“Around cone 04” sounds a little vague. I would trust what the label says, no more, no less. Mayco is not exactly a fly by night operation. It does seem like they say cone 06 is the target for these glazes. Prepare for runs at 04. 

Thank you for the advice! I think my biggest concern was more so regarding any fumes that could result from the firing since our kiln is inside our studio and we often have it running while there's students working in here. 

[neilestrick]

4 hours ago, semidoomed said:

I think my biggest concern was more so regarding any fumes that could result from the firing

Raku glazes are often high in metals, but that doesn't necessarily mean they'll fume any worse than a regular glaze. I assume the kiln is vented?

[Rockhopper]

23 hours ago, Kelly in AK said:

Do some test tiles and put them on a cookie.   . . . A lot of raku glazes are specifically designed to become interesting on being thrown into a trash can full of straw, red hot.

In addition to finding out if, or how much, the glaze will run,  the test tiles will let you see what the glazes look like without the reduction that takes place in raku process..  There's a good chance that without that step, they're going to look a lot different than expected - and your student may decide they don't like the results well enough to use it on the pieces they originally planned.

[semidoomed]

On 2/10/2024 at 6:27 PM, neilestrick said:

Raku glazes are often high in metals, but that doesn't necessarily mean they'll fume any worse than a regular glaze. I assume the kiln is vented?

Yes, our kiln is vented. I've personally have never done raku firing or used raku glazes.

[semidoomed]

On 2/10/2024 at 8:36 PM, Rockhopper said:

In addition to finding out if, or how much, the glaze will run,  the test tiles will let you see what the glazes look like without the reduction that takes place in raku process..  There's a good chance that without that step, they're going to look a lot different than expected - and your student may decide they don't like the results well enough to use it on the pieces they originally planned.

Thank you! I'm hoping our clay tests does fine with the glazes, since the clay is not specifically for raku. 

[Callie Beller Diesel]

@semidoomed if the glazes are only being fired to cone 04 and cooled in a normal firing, the clay body won’t matter a great deal. If they do want to pull the pieces out of the kiln while hot, it’s a good idea to wedge in a bunch of grog if there isn’t any already to help ease some of the thermal shock. 

[Pres]

I have done electric raku with an old Amaco electric kiln. We had a center courtyard in the HS that was all open. I ran an extension cord out for the kiln, and fired out side. We had the 20 gal metal trash can with wood shavings and sawdust from the wood shop. The pots were made with our regular clay. . .at that time a white earthenware that we wedged a bunch of grog into as Callie says. Firing started first thing in the morning, and at cone 04-06, unload and reduction in the trash cans occurred in the last period of the day when I had class. The pieces turned out well with great wax resist areas and crackled decoration with some metallic tones from the raku glazes that were more metallic. The blacks were really nice in contrast to the White raku glaze that crackled a lot. Kids loved as did a lot of the students that would watch from the courtyard windows on the 2nd 3rd and 4th floors. They usually closed their windows when we were unloading. Administration must not have like it because two years later they made a major renovation closing the area in for District wide Supply depot/warehouse! Make certain to unplug the kiln before opening as hot air is a conductor of electricity.  A major warning in the research I had done back then in some old books on firing and raku.

 

best,

Pres