Jump to content
Sign in to follow this  
docweathers

^5 Crystalline Glazes

Recommended Posts

    I just found what looks to be a very nice ^5 crystalline glaze recipe,  with some variations.  I know it's generally considered very difficult to get crystals under about  ^8, but apparently this lady has worked it out. Does anyone see any problem with it you see any problems with it?

http://glazestuff.wordpress.com/judi-buchanans-osl3-crystalline-glaze-5/

 

The writing on her  test tiles is very difficult to read. So I fiddled with the picture to make it quite a bit more readable.  It is attached. I think the MN means manganese but it could also mean magnesium.  Which makes most sense with the appearance of the test tile?

 

Also do you think the Cu  is copper carbonate or copper oxide?

 

 I've done a search for  Judi Buchanan and can't  find anything that fits.  Does anyone know her or how to contact her?

post-6406-0-31717300-1391552141_thumb.jpg

post-6406-0-31717300-1391552141_thumb.jpg

Share this post


Link to post
Share on other sites

We have two people at our studio who do macro-crystalline glazes below Cone 6 at home. Each type of macro-crystal type will form most actively at one specific temperature. They often cycle the temperature up and down to get exactly the zinc-silicate crystals they're looking for. 

 

All ^6 macro-crystalline glazes I've seen are silica with flux and virtually no alumina.  Judy's Silica to Alumina ratio is 16.75, while the ratio is 38.9 for the Frit 3110 recipe below - and an amazing 106.6 for the Frit 3134 under-glaze recipe!  Glass with very little structure allows the glass to de-vitrify and form these crystals.

 

Her information is pretty specific.

 

32.3%  Silica
27.9%  Custer Feldspar
18.9%  Zinc Oxide
  8.7%  Lithium Carbonate
  5.0%  Strontium Carbonate
  3.6%  Dolomite
  2.7%  Bentonite
  0.9%  Rutile

 

#1  Drop temp to1850F hold from 1 to 4 hrs.

#2  Drop temp to 1650F hold 10 min, Raise to 1900F hold 3 hrs, Drop to 1650F hold 10 min, Raise to 1900F let cool. - creates large center ring with border.

Schedules are continually being changed and  reversing the hold positions on #2 creates a crystal with a small center ring inside a wide one.

 

I think I'll try Judi Buchman's macro-crystalline glaze this weekend, using our regular slow-cool to see what I get.  I notice she doesn't prefer the elemental symbol Sn for Tin - Stannum never became a familiar to me.

 

The macro-crystalline people at our studio use frits, very similar to a Teal Blue breaking Honey Bab's has been trying to get more blue coverage on.  The person using this makes this glaze twice, once with 3134 and the other with 3110.  He applies the 3134 first, then applies the layer with 3110.

 

103.0%  Macro Crystalline Base -- Cone 6

  52.0%  Ferro Frit - 3110   or   3134   50%

  24.0%  Zinc Oxide                             20%

  24.0%  Silica 325 Mesh                     30%

  2.0%    Lithium Carbonate                   0%

  1.0%    Titanium Dioxide                      1%   Red Iron Oxide - Maybe these are a nucleation agents or it night be unnecessary.

0.5% to  4.0%   Coloring Oxide,  Cobalt, Copper, Nickel.

 

Just compare how close this recipe is to Bab's Teal Blue breaking Honey - except they use 24% Zinc Oxide instead of 20%.

http://community.ceramicartsdaily.org/topic/5581-nickel-still-in-the-dark/

 

With our six hour slow-cool between 1800F and 1500F these are the small crystals I got last weekend with Bab's Blue Teal breaking Honey nickel.

med_gallery_18533_643_927823.jpg

 

    I just found what looks to be a very nice ^5 crystalline glaze recipe,  with some variations.  I know it's generally considered very difficult to get crystals under about  ^8, but apparently this lady has worked it out. Does anyone see any problem with it you see any problems with it?

http://glazestuff.wordpress.com/judi-buchanans-osl3-crystalline-glaze-5/

 

The writing on her  test tiles is very difficult to read. So I fiddled with the picture to make it quite a bit more readable.  It is attached. I think the MN means manganese but it could also mean magnesium.  Which makes most sense with the appearance of the test tile?

 

Also do you think the Cu  is copper carbonate or copper oxide?

 

 I've done a search for  Judi Buchanan and can't  find anything that fits.  Does anyone know her or how to contact her?

Share this post


Link to post
Share on other sites

Not claimimg the glaze as mine, only labelled Babs because Bsiske?? sp. sorry,ran it thro' software with my name attached!

The glaze is from my old notebook and is prob. a Janet De Boos variation as I was using a number of her glazes around that time.

Give janet De Boos the credit or otherwise.

Share this post


Link to post
Share on other sites

Not claimimg the glaze as mine, only labelled Babs because Bsiske?? sp. sorry,ran it thro' software with my name attached!

The glaze is from my old notebook and is prob. a Janet De Boos variation as I was using a number of her glazes around that time.

Give janet De Boos the credit or otherwise.

Babs,

 

I have a recipe for a Janet De Boos Teal Blue glaze, cone 6 oxidation, in my workbook; was a studio glaze at a community studio I once took classes/taught at:

 

Teal Blue ^6 (Janet De Boos)

Neph Sye 35%

Whiting 18%

Ferro Frit 3134 12%

OM-4 ball clay 5%

Silica 30%

Total 100%

Plus:

Copper carbonate 4%

Tin Oxide 8%

 

The glaze has a tendency to hard-pan, so one would want to add 2% Bentonite to help keep it in suspension.

Share this post


Link to post
Share on other sites

Thanks Bciske! Will try this one to see if it is more suitable for domestic ware. WIll prob sub. a bit of zirc. forthe tin, price change from the 80's. I liked the darkness ofhte blue produced by the zinc/nickel but  a difficult glaze to handle.

Share this post


Link to post
Share on other sites

You did the search part and I have a big chemistry set.  There's a lot of people at our studio who were salivating over the crystals from last weekend.

 

I may not be able to follow her firing schedule anytime soon, but will rather use our 50 F slow-cool between 1800F and 1500F,

 

The Custer Feldspar should not be that fluid apart from the Strontium, Lithium and Zinc. 

 

I wish I knew more about this eutectic.  Anyone?

 

I have more experience starting Custer Feldspar melting with frit, like the Glossy Clear Liner in MC6G. 

http://www.masteringglazes.com/mastering-cone-6-glazes/glaze-reformulations/chapter-6-glaze-reformulati/glossy-clear-liner-with.html

 

I'd also like to see what happens to the Babs formula with more zinc. I left it mixed with some sodium silicate to try to tame down the veegum a bit.

Norm

I'm looking forward to seeing the results of this weekend's testing of Judi Buchanan's recipes. I always appreciate someone doing my homework for me :)

Share this post


Link to post
Share on other sites

Schran uses the  Ferro Frit 3110 / Ferro Frit 3134 approach I've seen most widely used.

 

Schran also explains the use of the 1% Red Iron Oxide in the glaze Bab's was using - as I suggested a nucleation factor.

 

http://www.creativecreekartisans.com/creativecreek_cone6cry.htm

  1. Glaze must be fluid to form crystals.
  2. Glaze coating needs to be thicker than usual.
  3. Glaze is best sprayed or brushed on, but can be dipped/poured.
  4. Glaze which is fresh, well mixed and screened works best.
  5. A fast firing and long soaking (1/2 to 4 hours) time produces more crystal growth.
  6. Fritting of compounds or use of frits, rather than raw materials, is recommended. Most frequently used frits are Ferro #3110 & #3134.
  7. High soda content is better than potash or calcium.
  8. Manganese or iron, under 2%, promote larger crystals.
  9. Zinc should range 10 – 35%.
  10. Titanium contributes to smaller, but evenly distributed crystals. No more than 10%.
  11. Alumina must be less than 10%.

Bill Schran works in this cone range. Here's a link to his info and recipies.

http://www.creativecreekartisans.com/

 

Lot of good into here

Wyndham

Share this post


Link to post
Share on other sites

Glaze drip trays for macro-crystalline glazes are often made of clay at the same time as the ware.  People often support the ware on a mixture of sawdust and alumina on the drip tray.   Macro-crystalline bowls fired this way are ground on the bottom with something like a jewelers wheel.

 

Other clever types design the "drip tray" into the the ware as a design feature.

 

What is the best way to make glaze drip trays for these runny glazes?

Share this post


Link to post
Share on other sites

I did my thesis on macro crystalline glazes at ^10 in 1973 . I I have a book on cone six macrocrystalline glazes that was written about 5 years ago. I am in Montana right now. Will post the title when I get home tomorrow

. the test on lower left is Mn in the glaze. The symbol for Manganese is MN. Magnesium is MG. nickel was one of my favorite Colorants along with tungsten and molybdenum.

marcia

Share this post


Link to post
Share on other sites

I made up this crystalline glaze today, but used Lithium Fluoride in place of the Lithium Carbonate.

32.3%  Silica
27.9%  Custer Feldspar
18.9%  Zinc Oxide
  8.7%  Lithium Carbonate
  5.0%  Strontium Carbonate
  3.6%  Dolomite
  2.7%  Bentonite
  0.9%  Rutile

 

The two test tiles may not get fired until next weekend as our shelves are actually fairly empty at the moment.

Norm

I'm looking forward to seeing the results of this weekend's testing of Judi Buchanan's recipes. I always appreciate someone doing my homework for me :)

Share this post


Link to post
Share on other sites

I want to confirm the fact that lithium is being used exclusively as a flux rather than participating in the crystal formation.  Lithium Fluoride provides somewhat more flux than Lithum carbonate while providing a similar COE.  The bonded Fluorine on the other end of the molecule can sometimes facilitate interesting things other than fluxing.

 

I might make up a Lithium Carbonate version tomorrow.

what is your thinking using Lithium Fluoride in place of the Lithium Carbonate.?

Share this post


Link to post
Share on other sites

 when I got your original post about your substitution in the glaze recipe,  I literally had the recipe out, a yogurt container on my scale and I was being around for the components. At this point, I think I will wait and see what you get before I mix up some. I've plenty else to do.

 

 Keep me posted

Share this post


Link to post
Share on other sites

Don't worry.  I'm going to be relying on you to test out the firings with the Heat Soaks for an hour or two.

 

I need someone like you to experiment with an their own kiln to find a slow-cooling schedule I can adapt to our slow-cool to maximize crystalline growth without significantly changing the look of all of our other glazes.

 

 when I got your original post about your substitution in the glaze recipe,  I literally had the recipe out, a yogurt container on my scale and I was being around for the components. At this point, I think I will wait and see what you get before I mix up some. I've plenty else to do.

 

 Keep me posted

Share this post


Link to post
Share on other sites

Cone 6 crystalline seem to respond well at 1800-1850f soak range. The zinc might do better around 20% but all this is subjective based on testing.Use calcined zinc ox if possible also, this will fit better than raw zinc.

Wyndham

Share this post


Link to post
Share on other sites

Thanks.  Currently our slow-cool is 50 F per hour between 1,800 F and 1,500 F, so I probably need to change this to start around 1,850 F.  Later, when I can,  I trying adding a longer heat batch based on what DocWeathers comes up with.

 

After mixing the original version today and making test tiles, I'll increase the Zinc Oxide to 20% in both versions and make additional test tiles.

 

Cone 6 crystalline seem to respond well at 1800-1850f soak range. The zinc might do better around 20% but all this is subjective based on testing.Use calcined zinc ox if possible also, this will fit better than raw zinc.

Wyndham

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  

×