Jump to content
Sign in to follow this  
docweathers

MFA Thesis on cone 6, Oil Spot glazes

Recommended Posts

Wow, pretty well written.. Love oil spots ... but results are picky at best ... I usually just cheat when I make them by using a granular iron oxide (magnatite I believe if I remembor correctly.) ... in an iron glaze it will easily achieve the oil spots even if reduction is not ideal or you are using a clay body that does not have decent iron in the ball clay to start with. Had a buddy In college that would also cheat with oil spots by giving his thrown pieces a dusting of granular iron oxide while it was still on the wheel so it had thicker and thinner particle effects much the same way as a flame would caress a piece in the kiln.

Share this post


Link to post
Share on other sites

Doc,

 

After reading through the thesis ... he explains how others fire oil spots at cone 10 ... but not how HE fires at cone 6 ... if you are having mixed results ... how do you fire, is it computer controlled or kiln sitter controlled? do you do an end soak? slow cool down? do you fast fire? slow fire? what is the average temp increase per hour from cone 3-6?

 

This will be the key to trying to figure out how he got his oil spots to appear.

 

Most likely he slow ramps the kiln at the end so the glaze has time to release the gas and heal over when the glaze is in the liquid state ... if kiln sitter controlled, that might be trying to find a way to fire slower (get it near temp with elements on high, then move all but the very bottom switch or two to medium so it is forcing the kiln to heat slower. ) or if you have a computer controlled kiln, letting it soak at the end for about an hour or so.

 

generally an oil spot is a liquid high iron glaze with a glaze that moves less on top, which is why he went with a more stable white glaze he could add colorants to. The idea is to get the top glaze to pop and seperate without healing ... and sometimes that requires long soak times for the bottom glaze to go crazy.

Share this post


Link to post
Share on other sites

I am firing manually with a gas kiln. I have been climbing at about 400° per hour.

 

I have been corresponding with Vickory. He as been very helpful. This is the firing schedule that he recommends

 

500 degrees an hour to 2100then 100 an hour to 2232, 30 minute hold,500 degrees an hour to 2000, 10 minute hold 500 degrees an hour to 1900, 10 minute hold 500 degrees an hour to 1800, 10 minute hold.

 

I like your cheating idea with granular iron oxide. I will definitely experiment with this.

 

Part of my mixed results is been do to the extreme particularly on vertical surfaces. I'm getting ready to run some line blend tests, as victory does in his thesis, on increasing the dolomite to make it more suitable for vertical surfaces.

 

thanks for the suggestions Larry

Share this post


Link to post
Share on other sites

I just found this very nice MFA thesis on Cone six oil spot glazes. I thought others might find it useful. It is attached.

 

 

Thanks for sharing! It is a well written MFA Thesis. I have had little luck with cone 6 oil spots, after reading this I'm inspired to try again.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×