Basic Glaze Recipe To Work/experiment (Newbie Question)

[PottaFella]

After my initial experiments with the Emmanuel Cooper semi-crystal glaze which gave somewhat mixed results, I've decided I need to use a more straightforward glaze recipe and one that I can experiment with colouring etc.

 

Apologies for the basic nature of these questions...

 

I have found two Cone 6 (1240C) recipes that includes photos of lots of different colours for me to play with so I can test my kiln and on different clays etc. On stoneware they are going to hopefully give a nice effect without using too much electricity.

• It would be very helpful if the experts could tell me if these look like good recipes to start with...

 

matt glaze

% (by weight)

 

Soda Feldspar 54.0

China Clay 28.0

Whiting 8.0

Dolomite 6.0

Zinc Oxide 4.0

 

 

semi-matt glaze

% (by weight)

 

Soda Feldspar 70.0

China Clay 13.0

Dolomite 5.0

Whiting 4.0

Zinc Oxide 5.0

Quartz 3.0

 

• Neither of these shown in the photos as a good white - should I find a different recipe for that or should adding some manganese oxide be sufficient?

 

• Can anyone suggest a basic clear glaze that would be a good match for these recipes, say if I wanted to have half of a pot a colour and half clear glazed over a sketch.

 

• I am thinking to use 5kg of dry material to make a bucket of glaze – does that sound about right?

 

• If I want to experiment with adding colours, is the best way to mix a small quantity of dry material (say 100 grams) in a yogurt pot and  add oxides to that, or is there a better way by mixing a large amount of base glaze (liquid) in a bucket and then drawing off small amounts?

 

Thanks again for any advice!

[RuthB]

These are very important questions, no apology necessary. Some more information would be helpful. I'm not sure I understand your goal. You mention semi-crystal. Are you looking for a micro crystalline result with various colorants or just a base white glaze to which you can add various colorants for a painterly effect. Crystal growth of pyroxene requires slow cooling, which is much easier to do with a computer controlled kiln. You may find this chapter in Ian Currie's Stoneware Glazes: A Systematic Approach helpful in understanding the role of magnesium (not manganese) in glazes. Also see Currie on zinc in glazes for its effects on various colorants. http://stonewareglazes.currie.to/book/page/71/24#topnav

 

5Kg will make about 2 - 3 gallons. 

 

 

When I want to test various colorants, I wet mix up 1000 g of the glaze, and then divide it equally into 5 graduated containers. If all the

containers are the same,you can easily fill them to the same line and you can verify by weight that they all contain they same amount of dry glaze (200g).

I have found that the error margin for 100g is too large when testing colorants, 200g seems to work better. 

 

Good clear = no crazing? May take a bit of work to achieve and depends a lot on your clay body. What doesn't craze on one body may craze on another. 

The finer the craze lines, the poorer the fit between glaze and body; the expansion and contraction of the glaze and body are very different. Sometimes

crazing can be corrected by adding more silica or by changing some of the silica to a finer mesh. Ceramic Review published an article on correcting

crazing a few years ago and gave some diagnostic glaze recipes. I will try to find it. In the meantime, if you have tested a clear, check how fine the craze lines

are as a starting point. 

 

Ruth Ballou

Charleston, Sc

[PottaFella]

You mention semi-crystal. 

Thanks Ruth. The semi-crystal glaze was something I tried before but I found was perhaps too complicated, so the recipes in my post are for more straightforward glazes (matt and semi-matt) which I hope to learn to use before embarking on anything too complex.

 

That is very helpful about mixing up 1,000 grams of a base glaze and divide into 5 lots, that will save me lot of fiddling with powders!

[Chilly]

 You may find this chapter in Ian Currie's Stoneware Glazes: A Systematic Approach helpful

Hi Ruth

 

Was the underlined text meant to be a link?

[PottaFella]

 

 

 

The authors of "Mastering Cone 6 Glazes" named it Variegated Slate Blue, fired to ^6 with two hours of slow-cooling between 1,800 F and 1,500 F.

 

 

That is a great effect thank you for posting it. I am not certain in the UK we can get all the frits. My supplier lists only Ferro Frit 3110, High Alkaline Frit, Calcium Borate Frit, Lead Bisilicate Frit, Lead Sesquisicilate Frit and Standard Borax Frit.

[RuthB]

 

 You may find this chapter in Ian Currie's Stoneware Glazes: A Systematic Approach helpful

Hi Ruth

 

Was the underlined text meant to be a link?

 

Sorry, the link to the chapter on Magnesium glazes accidentally edited out.... Here it is: http://stonewareglazes.currie.to/book/page/62

[Marcia Selsor]

This is from several years ago on the forum. It is for experimenting with colorants. Note, if you want a white glaze, do not add Manganese which is a dark colorant. Tin ox., zircopax, or super pax are opacifiers which give you a white.As Ruth mentions Magnesium is a possibility. It also can turn

Cobalt into lavender.you could use a base glaze with dolomite as your source of magnesium.

 

Below is an exercise I assigned to students for mixing 4 colorants with a base glaze

 

"TJR

That is somewhat like what my classes use to do for color blends. I gave them a worksheet but here was the difference.

 

Using 6 cups A,B,C,D,E, and mixing cup. . Mix 250 grams of base glaze, add to water, sieve, and divide evenly into the first 5 cups putting 50 grams of the base into each cup. Then I would assign colorants into the last four cups. This is just an example:A=Base without colorants. B= 5% Red Iron Ox., C=1% cobalt carb, D=3% Rutile, E=3% copper carb. Add to the cups and sieve cups

Have 15 test tiles numbered 1 to 15

First row A=1 B=2 C=3 D=4 E=5

second row add teaspoon of A with teaspoon of B into mixing cup and apply to test tile 6. The is A+B on 6 A+C on 7, A+D on 8, A+E on 9

third row B+C on 10, B+ D on 11, B+E on 12

Fourth row C+ D on 13 , C + E on 14

Fifth row D+ E on 15

You end up with 15 separate colors.

You should also test the combination of all the colors. "

The colorant are hypothetical. Just pick some that you have available.

Marcia

 

Here is my favorite base glaze for ^6 that I fired in reduction for a few decades. It also works in oxidation but the mentioned colorants would respond differently. It has a great surface for functional pots.

 

 

This is a glaze posted on 12/4 /10 in response to a request for a yellow buttercup , not mustard glaze

Marci’s Matt ^6 Reduction

 

 

EPKaolin 1150 19.5

 

Dolomite 1000 21.2

 

Neph Syenite 1900 32.2

 

Silica. 900 15.2

 

Whiting. 200. 3

 

Gerstley Borate 500 8.4

Total. 5650. Total 99.5

The numbers above on the left are for half a five gallon bucket. The smaller numbers on the right are the close to 100 batch formula. Just multiply x 2.5 mix with water and sieve. divide into five even amounts in cups. After adding the colorants as described above, sieve again .

 

Variables:

 

Blue 1% Cobalt Carb

 

LightGreen1.5%Nickel Carb + 1.5%RedIron Oxide

 

Gray 2.5% Rutile +1.5% Nickel Carb

 

Warm Blue 1% Cobalt Carb+ 5%

 

Rutile OR try using only 5% Rutile

4% Rutile and 3% zircopax. To brighten it up , reduce the zircopax

 

 

Marcia

[bciskepottery]

Here is a link to a frit substitution chart. Should help your distributor get you the right frit.

 

http://www.ceramicstoday.com/frits.htm

[High Bridge Pottery]

I have no experience with cone 6 glazes, but I would just pick the easiest one to make and go from there.

 

I started off with one recipy that ended up crazing and such, but with a bit of tweaking - changing out the higher expansion oxides for lower and messing around with silica content I now have a really good matt white and shiny blue or green. Just pick a base glaze that you feel you can start to understand then go from there.

 

I got a good book for Christmas and will post a few more cone 6 up for you when I am not at work.

[PottaFella]

All those links are amazing, I have a lot of reading and experimenting to do, thank you so much.

 

 

Pemco, Massey-Ferguson and other European suppliers provide equivalent frits.  You'll be very limited in your choice of firing at Cone 6 unless you use frits.

 

High Alkaline frit is 3110.  A high Calcium borate frit would be like 3134 or 3195.

 

Frit 3134 is essentially a low-fire clear glaze with NO alumina, so you can mix it with kaolin to create a self-suspending glaze. Ask your supplier which of their frits supply this spec.  http://www.bathpotters.co.uk/frits/c94 Bath also offers 3124 and their "low expansion frit" would be like 3249.

 

This is a chart of equivalent frits. http://www.ceramicstoday.com/frits.htm

 

Alisa Clausen, a potter in Denmark has made all of these glazes with European frits.

http://www.stonecropstudio.com/potters.shtml

http://www.flickr.com/photos/glazes/sets/

 

Ferro Frit  3110  ^08  - Hi COE |19|  6% Ca, 18% Na-K, 2.6% B

Ferro Frit  3124  ^05  - |5.5|  14% Ca, 7% Na-K, 14% B   3134+Al

Ferro Frit  3134  ^015  - |999|  20% Ca,10% Na, 23% B

Ferro Frit  3195  ^08  - |3.8|  11% Ca, 18% Na-K, 23% B

Ferro Frit  3249  ^04  - anti-craze |3.2|  4% Ca  12% Mg, 29% B

Ferro Frit  3269  ^016  - Hi COE |10.12|  4% Ca, 1% Na-K, 15% B, 1% Zn

Ferro Frit  5301  ^013  - Fluorine |11.41|  2.4% Ca, 19.5% Na-K, 12.5% B,  9% F

 

I'd also suggest buying the "Mastering Cone 6 Glazes" book and becoming a level 2 member of Digitalfire which has lists of equivalent material from around the world.

 

http://digitalfire.com/4sight/material/frits.html

 

 

 

I am not certain in the UK we can get all the frits. My supplier lists only Ferro Frit 3110, High Alkaline Frit, Calcium Borate Frit, Lead Bisilicate Frit, Lead Sesquisicilate Frit and Standard Borax Frit.

 

 

[High Bridge Pottery]

Here are some that I have,

 

Wide-firing clear base glaze 1200-1260 Semi translucent in oxidation

 

Feldspar (soda)  - 38

Whiting - 14

Zinc Oxide - 12

Ball Clay - 6

Flint - 30

 

1.5% Copper Oxide gives turquoise in oxidation

2% Manganese dioxide gives iridescent blue-pink in oxidation

 

Smooth white glaze

 

Feldspar - 37

Whiting - 15

China Clay - 8

Flint - 37

Bentonite - 3

 

Semi matt clear base glaze

 

Feldspar - 65

Whiting - 20

Flint - 12

Bentonite -3

 

Just a few for you to think about, there are many similar glazes that contain different ingredients but I tried to just pick a few with the same ingredients. I tend to just substitute flint for quarts as I find it works better as the company I buy from seem to grind it up better.

I have never tried these myself and just taken them out of a book but it is a start for you.

 

I get my ingredients from http://www.ctmpotterssupplies.co.uk/ Only ordered from them three times but each time they have been very good.

[ayjay]

 

 

I am not certain in the UK we can get all the frits. My supplier lists only Ferro Frit 3110, High Alkaline Frit, Calcium Borate Frit, Lead Bisilicate Frit, Lead Sesquisicilate Frit and Standard Borax Frit.

 

Scarva keep all of the commonly used American frits and can supply by mail order.

 

Finding an easily available UK substitute will almost certainly work out cheaper and more convenient.

[lwa]

Hi Oly,

 

I'm in a similar boat to you - a beginner searching for a few basic glazes to work with.

 

I just wanted to add my voice to those recommending Mastering Cone 6 Glazes, especially if you want to make functional/food use pots. I've found it very useful - It's the only book I've yet come across which really addresses specifically functional glazes. All the other glaze books I've looked at either say nothing at all, even while presenting lead based and barium based glazes, or just have the disclaimer "do not assume any of these glazes are safe".

 

The only caveat is that it's all based around US materials, so you have to get your head around the glaze oxide formula to make good use of it...

[PottaFella]

Many thanks.  I've been given a book here in the UK - cone 6 glazes by Michael Bailey which seems pretty well thought out – but it doesn't hardly use the frits that seem to be so popular over there.

 

 

Hi Oly,

 

I'm in a similar boat to you - a beginner searching for a few basic glazes to work with.

 

I just wanted to add my voice to those recommending Mastering Cone 6 Glazes, especially if you want to make functional/food use pots. I've found it very useful - It's the only book I've yet come across which really addresses specifically functional glazes. All the other glaze books I've looked at either say nothing at all, even while presenting lead based and barium based glazes, or just have the disclaimer "do not assume any of these glazes are safe".

 

The only caveat is that it's all based around US materials, so you have to get your head around the glaze oxide formula to make good use of it...

[lwa]

That's actually the book I took the quote "do not assume these glazes are safe to use" from! I like that book too (I think since taking up pottery i've spent about 5 times as much money on books as on clay!). But do take him at his word regarding safety. The 'perfectly balanced' Base Glaze 1 presented in chapter 3 is probably good for functional pots, but the deliberately unbalanced glazes in the following chapters are very likely not...