rutile blue

[oakhillstudio]

Oakhillstudio

 

I have very mixed results with rutile glazes. Sometimes they come out spectacularly and sometimes they are a dull tan with bubbles erupting from the surface. Could anyone make a recommendation as to source and firing schedule? Also...any guidance on how to elimliminate blisters would be greatly appreciated! FYI...I have read every entry on the web that I can find.

[Mark C.]

What Temp are you firing to? What Temp are you firing to?how much are you reducing?We will need to know before answers are tuned

For now I will say mild reduction for me and I buy my rutile in 50# bags from Laguna clay and make my own glazes-of in the case of my rutile blue I have them make it for me by the ton now so I can have the time to make other glazes.

Mark

[oakhillstudio]

Thanks for the quick response. I fire to cone 10 reduction. Following John Britts firing schedule...I would say that I fire moderate to heavy reduction. I have mixed light and dark rutile as i had bags of each from long ago. I am testing that mix against light rutile that I got from Bailey.

[Mark C.]

Thanks for the quick response. I fire to cone 10 reduction. Following John Britts firing schedule...I would say that I fire moderate to heavy reduction. I have mixed light and dark rutile as i had bags of each from long ago. I am testing that mix against light rutile that I got from Bailey.

 

 

My rutile in 4 decades has always changed color at various times with little change in my final glaze results. I always buy 50 # bags. Their have been several large color swings in past few years. Let us know if you find any final color differences-I have not .

Weld Rod Titanate one of the larger companies has been bought out and the color changed when that happened (I have a bag of that now as well as another company) one is light one is dark.

Back to rutile woes -I'm not up on Johns firing schedule if you want to post it great if not I will add that more reduction early can cause pitting and well as what clay body its on. What clays are you using? stoneware is more problematic than porcelain . I used stoneware for over 15 years with very mixed results due to pitting and when I went to all porcelain it really helped. Pitting still occurs but rarely now. Clean bisque ware is key as well as glaze thickness (not to thick). I do not use cones in bisque anymore (past 15 years or more-just my digital meter and eyeball but make sure your not underfiring bisqueware.

I measure my glaze water content with a hydrometer (1520) and use an oxygen probe for reduction repeatability.My new meter reads upper 30s to low 40s

If you are firing seat of the pants reduction is the lower spy plug have flames or not?

If you are using any of these things what are the numbers??

Hope some of this helps

Mark

[oakhillstudio]

Thanks for the quick response. I fire to cone 10 reduction. Following John Britts firing schedule...I would say that I fire moderate to heavy reduction. I have mixed light and dark rutile as i had bags of each from long ago. I am testing that mix against light rutile that I got from Bailey.

 

 

My rutile in 4 decades has always changed color at various times with little change in my final glaze results. I always buy 50 # bags. Their have been several large color swings in past few years. Let us know if you find any final color differences-I have not .

Weld Rod Titanate one of the larger companies has been bought out and the color changed when that happened (I have a bag of that now as well as another company) one is light one is dark.

Back to rutile woes -I'm not up on Johns firing schedule if you want to post it great if not I will add that more reduction early can cause pitting and well as what clay body its on. What clays are you using? stoneware is more problematic than porcelain . I used stoneware for over 15 years with very mixed results due to pitting and when I went to all porcelain it really helped. Pitting still occurs but rarely now. Clean bisque ware is key as well as glaze thickness (not to thick). I do not use cones in bisque anymore (past 15 years or more-just my digital meter and eyeball but make sure your not underfiring bisqueware.

I measure my glaze water content with a hydrometer (1520) and use an oxygen probe for reduction repeatability.My new meter reads upper 30s to low 40s

If you are firing seat of the pants reduction is the lower spy plug have flames or not?

If you are using any of these things what are the numbers??

Hope some of this helps

Mark

 

[oakhillstudio]

Dear Mark,

Thanks for your help. In answer to your questions...i use white stoneware with grog from Sheffield Clay Co in MA. I fire with a strong reduction atmosphere (500-600) starting at around 1560 degrees farenheight all the way through untill my kiln reaches cone 10. I end up with a considerable soak from cone 9 to 10 as the temperature climb under reducing conditions in my kiln is very slow. This works out wonderfully for my reds...

 

I do see a nice flame jet from my bottom spy hole. It is about 6 inches long.

 

I wonder if I am just using the wrong glazes? Perhaps I should try firing my reds at a different time than my rutile and barium blues, for that matter. I use john britts rutile 11 and rays rutile taken from his book which is available free on line....I swear....that guy is a saint! Do you have any glaze recommendations? I will certainly try less reduction....

 

Be well and thanks so much for your help,

Sharon

[Mark C.]

My experience is my reds like more reduction than most other glazes and that especially true in the early stages as well. I never add barium glazes to my standard reduction loads.

To me it sounds like you really are doing a heavy long reduction-my bottom spy plug never has a flame lick to it

 

My Barium glazes are fired cooler and with a lot less reduction than say reds

My rutile glaze like reduction and long soak times near cone end points -this helps lay down the surface if its bubbling.

What is Rays name so I can view these glazes.

I'll look up Johns rutile 11 in his book and see what it looks like

Mark

[oakhillstudio]

Thanks for your rapid response. Both rutile glazes are in john britts book in his chart on rutile blue recipes. Most of them are not "blue" for me, although Rays rutile can be a gorgeous blue purple.

 

By the way...I have a Bailey Kiln...18 cubic feet..2 years old. I love it but what do I know?

 

Be well,

Sharon

 

 

 

[qute name=Mark C.' date='30 August 2012 - 05:38 PM' timestamp='1346366284' post='21555]

My experience is my reds like more reduction than most other glazes and that especially true in the early stages as well. I never add barium glazes to my standard reduction loads.

To me it sounds like you really are doing a heavy long reduction-my bottom spy plug never has a flame lick to it

 

My Barium glazes are fired cooler and with a lot less reduction than say reds

My rutile glaze like reduction and long soak times near cone end points -this helps lay down the surface if its bubbling.

What is Rays name so I can view these glazes.

I'll look up Johns rutile 11 in his book and see what it looks like

Mark

 

[Mark C.]

After reading Johns book last night about his firing schedules and looking at the rutile glazes which are similar to mine. I can see way you may be having issues.

Your white stoneware may be a factor combined with the heavy reduction you like for reds.

I would try a sample of a non stoneware body in same load and see what turns out like a porcelain body- I had tones of issues with stoneware bodys (white or brown) and rutile .

I switched to porcelain and that almost went away with rutile issues. Yes some pitting can still occur but its less.

I'd fire the Barium glazes in a separate fire with less reduction and test some rutile in this load as well on all bodies to see what turns up.

Id that schedule making any carbon coring? ( break a pot and look at inside of clay body?)

Hope this helps-I use about 1 ton of rutile blue glaze every 4 -5 years here. I have it made by the ton at one time so I can mix the other 15 glazes I use and its one less thing.

Mark

[oakhillstudio]

Thanks so much for all this help. You are a godsend. In answer to your questions...I do not get carbon coring with the firing schedule that I use as i bisque very slowly. My problem is that i only get beautiful blues on occasion with the same glaze. I will definitely try your suggestion to separate the reds from the blues and a do a lighter reduction. Maybe that is the explanation....when the reduction is heavy i just dont get blue but when the reduction happens to be light by chance of location in the kiln....the blue shines. Could i bother you to suggest a rutile recipe that is most likely to work? Which of those listed by jb do you think I should start these experiments with?

 

I will also make some porcelain test tiles to get to the bottom of all this.....

 

 

I unloaded a kiln today in which I tested light vs dark rutile + or - titanium in durhams blue rutile glaze (yellow iron oxide) . You were right. My 30 year old batch of dark rutile came out very similar to my new light rutile....kind of indistinguishable. Interestingly, the type of iron oxide made a huge difference. Red was awful muddy brown while the yellow made the rutile just glow a brilliant midnight blue.

 

I will update you as to my progress,

Again, thank you for your generosity,

Sharon

 

 

 

 

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After reading Johns book last night about his firing schedules and looking at the rutile glazes which are similar to mine. I can see way you may be having issues.

Your white stoneware may be a factor combined with the heavy reduction you like for reds.

I would try a sample of a non stoneware body in same load and see what turns out like a porcelain body- I had tones of issues with stoneware bodys (white or brown) and rutile .

I switched to porcelain and that almost went away with rutile issues. Yes some pitting can still occur but its less.

I'd fire the Barium glazes in a separate fire with less reduction and test some rutile in this load as well on all bodies to see what turns up.

Id that schedule making any carbon coring? ( break a pot and look at inside of clay body?)

Hope this helps-I use about 1 ton of rutile blue glaze every 4 -5 years here. I have it made by the ton at one time so I can mix the other 15 glazes I use and its one less thing.

Mark

[Mark C.]

Thanks so much for all this help. You are a godsend. In answer to your questions...I do not get carbon coring with the firing schedule that I use as i bisque very slowly. My problem is that i only get beautiful blues on occasion with the same glaze. I will definitely try your suggestion to separate the reds from the blues and a do a lighter reduction. Maybe that is the explanation....when the reduction is heavy i just dont get blue but when the reduction happens to be light by chance of location in the kiln....the blue shines. Could i bother you to suggest a rutile recipe that is most likely to work? Which of those listed by jb do you think I should start these experiments with?

 

I will also make some porcelain test tiles to get to the bottom of all this.....

I think JB rutile 11 or Rays is a fine start-My rutile glaze needs reduction just not as much as my reds.

I would try the clay body samples in porcelain and put them in your red fire for starter and see if this along does the trick before changing up firing schedules. All rutile glazes are problematic over time.

I accept a few pots with pitting now and again and usually just re fire them in a slightly cooler but reduced spot as re-fire's tent to run more if fired hot again with rutile on them.

Mark