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does anyone recognize the source of this glaze recipe?


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this is for a very nice clear glaze that seems to work on many different clay bodies.   source unknown but i always try to find out the origin of any recipe before i use it.

clear glaze cone 6

gertsley borate          21

wollastonite                    8

neph sy                           30

EPK                                  10

silica 325                        31

         total                      100

thank you.   

Edited by oldlady
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Cone 6

Looks similar to one we use for a super gloss studio glaze that currently works on our stoneware, Bmix, English 365  and frost porcelain. I honestly cant remember where the base came from  but we changed to wollastonite and it has a touch more boron to melt over heavy underglaze. It has been in use for more than a year and plays well with mason stains for a celadon flowing look. This recipe look similar to the one you posted. I believe I just located it in stull and fired a time or two till I got the gloss I was seeking so not a bunch of thought went in it.

Recipe and recent bowl below is frost with clear inside and 2% grey mason stain outside.

E6C44850-609E-411D-AC38-2A14D051F2B5.jpeg.77614357d2edac312ad4ad81700de657.jpeg

E5295EF6-BC02-4009-84C5-1E5819B86C4C.jpeg.683246cb0f3500d67ebb8ef95f600461.jpeg

Edited by Bill Kielb
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thank you bill.     my search is for a no zinc glaze that might work with green slip.   i do not know any chemistry and i see that the amounts in your recipe are significantly different from what i posted.     then i saw "flowing look"  and wonder if you are referring to a glaze that slides down the pot or something else.   your photo shows a wonderfully shiny glaze on the interior that looks similar to the one i tested on  a tiny bowl so i wonder which recipe is better?    the one i posted is used in a shared studio and teaching situation with all kinds of clay, some just whatever is left over and pugged together.

have you used it over green underglazes or slips?  does it change the  color of the underglaze or slip?

i ABSOLUTELY never want a glaze that runs or slides down.

Edited by oldlady
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I think they are pretty similar chemically, will put them in glaze Calc later and compare. I try and get 10 - 20 % clay in mine usually to try and make sure it stays suspended so that’s likely how my apportionment came to being.

Yes, we made this to work over heavy underglaze so the boron was upped until it successfully smoothly melted over Red And Black underglaze I believe,  but other colors can be refractive as well. We have an artist who uses this over all her slip decorated stuff so success there as well for over a year.

 In the picture  above the inside is just the clear over frost porcelain. The outside glaze is the  same clear with about 2% mason stain to get the grey celadon look. It is super glossy and has worked over many clay bodies for us so hopefully if you try it it will work for you.

we developed a companion matte clear as well with the same goal of being easy to use over heavy underglazes and still fully melt. I’ll post below. Both had to be zinc free to avoid color issues, melt well and work with the many studio claybodies. Both have worked well for over a year now with no major issues.

the pictures below: Marcias matte recipe,  gloss over green and black underglaze, (I think we tinted the gloss with stain a  bit as well) and matte over heavy underglaze decoration.

If folks want less matte they just add Silica until they like the finish. I tested this all the way out to gloss I believe. Pretty sure it’s in one of our glaze adjustment videos, I will look and post if I find it. Neither of these glazes move at cone 6.

1CD4D201-4D59-4AE0-8767-7ABA82D83A5F.jpeg.64d21ca211bc13b4891e1aa079f0d6e6.jpeg1C129D44-1E31-4E0B-B590-E7A9253FFC17.jpeg.437fb9e0530302ff4b9edd96bece1d82.jpeg2EB2A550-2275-4B79-8D23-124732B40467.jpeg.1a8b2763708e229a1d437735d7eaee27.jpeg

Edited by Bill Kielb
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Great to hear and hope they work as well for you. I took a little time to analyze and if I take your original recipe, my observations are: 

  • OK flux ratio, not great but OK
  • A bit Too much boron at cone six for me
  • More Silica than needs to be for a gloss so reducing Silica in this recipe should make it glossier.

so lots of opinions out there and this is just one  but I would make adjustments to reduce the silica, move the RO just a bit and reduce the boron. When I do this your recipe and mine end up to be reasonably similar, so who knows.   It or some form of it, may have been the origin of mine.

Hopefully you have a number of winners here.

The original recipe and reformulated below it  just for your information. This is just a desktop modification which requires testing by fire. If the reformulate works, it saves you some chemicals at each mixing.

Best of luck!

6DEE2BA8-3B82-4405-B82F-20718E9CB432.jpeg.2ac1983a19b3325a2b25692d694caac6.jpegAA9A99FE-9EBA-44CD-82D2-FF372842C273.png.f07ac66459c24c3ce72774fb450656db.png

 

Edited by Bill Kielb
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Hi Lady,

Recipe you posted is exact match for "Wollastonite Clear" from a book I borrowed last year - not sure which one now* - credited to Bethany Krull; I see same recipe in a few other places...

Any road, I did choose the glaze as one of the four clears to try out.

I'm planning to keep it (pending the results of more testing), particularly for Aardvark SRF, as it clears the micro bubbles better (much better - no bubbles at all) than the other clears I'm trying. SRF has a high absorption rate, yes, however, the colour is beautiful, it throws and walks really well; it's on my keeper list!

The other clears I selected, a variant of Kitten's Clear and two of Tony Hansen's mid fire low expansions, don't clear the bubbles on SRF; all four craze over the bmix and lighter red clay. The lower expansion crazes less - more work to do there, or phase out the bmix and light red clay.

*The book, as I recall, had pictures of many artists' work, and recipes for all glazes; I liked the look of the glaze ...hmm ...our library doesn't retain checkout history, hmm ...my guess is that it was this book!! Glaze-The Ultimate Ceramic Artist’s Guide to Glaze and Color by Brian Taylor and Kate Doody

B)

Edited by Hulk
3+1=4
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thank you, hulk

the potter who gave me the recipe said he got it from a book but did not remember which one.   

i am still trying out white clays to replace my little loafers.   i threw several bowls with Standard  365 and they were given raw to a fund raiser for a shelter nearby.  they were bisqued and glazed in a shared studio and the finished product was much whiter than my more ivory colored little loafers.  should be since it is a porcelain.  the glaze was really good on most of them but i noticed that over Stroke and Coat, which is a glaze and not an underglaze or slip, there are slightly rough spots.  since these were only on those small flowers that i sponge on, i do not think there will be a problem with the bowls.   since i single fire and put the stroke and coat over my white glaze, i have never seen the kind of roughness these flowers showed.   maybe the bisque firing of the S&C caused it.  

the slipped ones came out great.  AND the leaves were still GREEN!  so i really look forward to using that clear.   along with the great one from Min last year, i should have a perfect choice for the clay that i will use.   probably not 365, it reacts like rubber to tools, no crisp lines even with titanium tools.

both clays were glazed with absolutely no bubbles visible on any of them.   i have seen those foamy looking tiny bubbles on other people's work but nothing like that here.  BTW, some of the bowls were made with all the scraps and trimmings of student work.  that clay is pugged and put out for student use,   no telling what that stuff is but no bubbles on any that i saw.

i will try to get the book you suggest was the origin.  it is one i have not seen so i will ask my library to get it on an inter-library loan basis.  thank you so much for the lead.:D

Edited by oldlady
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  • 3 weeks later...

update for hulk and bill.

i got the book from our county library system, not in my local library.   hulk, you are amazing.   what made you try this glaze?  it was used only on the eyes and nose of the two sculpted animals shown.  only a pin dot in the photos!   (i am returning the book today, the rest of it is just not my kind of thing.  the folks who want to smear glaze might be interested, i guess i am too old for that.)

bill, life intervened in my plans to make glaze.  it is on my schedule for this week, or next since this one is half over.

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Hi Lady!

I copied several pages from that book, was just looking at glazes and picking out some recipes to start with, and from said list of recipes, generate first "big" materials order.

I just liked the look, it looked good to me in GlazeMaster, and I like to say "Wallastonite" as well ...the materials come up in at least one other glaze on my short list, aah, that's a factor too.

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  • 4 months later...
On 7/30/2019 at 5:03 PM, Bill Kielb said:

 

the pictures below: Marcias matte recipe,  gloss over green and black underglaze, (I think we tinted the gloss with stain a  bit as well) and matte over heavy underglaze decoration.

If folks want less matte they just add Silica until they like the finish. I tested this all the way out to gloss I believe. Pretty sure it’s in one of our glaze adjustment videos, I will look and post if I find it. Neither of these glazes move at cone 6.

1CD4D201-4D59-4AE0-8767-7ABA82D83A5F.jpeg.64d21ca211bc13b4891e1aa079f0d6e6.jpeg2EB2A550-2275-4B79-8D23-124732B40467.jpeg.1a8b2763708e229a1d437735d7eaee27.jpeg

Hi Bill:

This matte looks great. I am a neophyte in this. Just trying to get a strong, stable workhorse or two base glazes. Cone 5 or 6.  I ran my first tests and too many of them came out a little opaque, mostly from bubbles and pinholing, especially on dark clay bodies (710 in particular). I think I may have over cooked them (peak soak time too long, maybe an hour); did not let them slake long enough; but mostly that I brushed them on too thickly. 

I also plan to drop and soak (drop peak 100 degrees and let it soak there) as a way to reduce bubbling. 

My question is where are you getting that awesome software, chart stuff? Where it will tell you where your mixture lies in a spectrum from matte to gloss, and help you see the chemical content so well?

thanks 

Michael 

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2 hours ago, Michael D said:

Hi Bill:

This matte looks great. I am a neophyte in this. Just trying to get a strong, stable workhorse or two base glazes. Cone 5 or 6.  I ran my first tests and too many of them came out a little opaque, mostly from bubbles and pinholing, especially on dark clay bodies (710 in particular). I think I may have over cooked them (peak soak time too long, maybe an hour); did not let them slake long enough; but mostly that I brushed them on too thickly. 

I also plan to drop and soak (drop peak 100 degrees and let it soak there) as a way to reduce bubbling. 

My question is where are you getting that awesome software, chart stuff? Where it will tell you where your mixture lies in a spectrum from matte to gloss, and help you see the chemical content so well?

thanks 

Michael 

I’ve never used this on red clay but this has more boron to purposely melt early and fully over heavy underglaze. It’s a true matte so no need for cooling cycle or hold of any sort, this act will likely destroy the look. The matte you see above is a very normal 7 hour glaze firing, no holds, no cool down, nothing fancy. Let me know if you want a typical schedule to try.

The software is a free spreadsheet, Katz ceramic materials workshop. The version you see is one we got permission from him to modify and redistribute to our glaze group. We added some macros (for ease of data entry) and color and chem research to ours. You can get his at his website or message me and I will get a copy ready for you.

last comment, clear glazes, generally even, reasonably thin coat. Both of these, the high gloss clear and matte,  were tested with two three second dips in a fairly thin mix, SPG about 135-138. We have folks brush apply these with no issue, the piece above was sprayed. One gal adds a drop of Darvan To her cup of working glaze to brush her large projects (Go figure, works for her) 

Edited by Bill Kielb
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