Glaze Development for Dummies

[Dani Montoya]

If anyone wants to write this book I would be the first to buy it. 

I am just now attempting to do some glaze development and I am learning on my own, no classes or a teacher or mentor etc because there are none around me.

I bought the MC6 and have been working with that but I still end up starring blankly at my triple beam scale, surrounded by bags of white powder, all decked out in my respirator!!  (Think Breaking Bad, oh I wonder what my neighbors are thinking)

It is so overwhelming to me! I am not a chemist so that throws me for a loop.

Does anyone have any words of glaze wisdom for me? A book I can read, online class I can attend. 

[Robert Coyle]

Sorry Dani... you just can't be a dummy and develop glazes, but you don't have to be a chemist either. Decide what you want your glaze to look like then try to find one that someone already made that looks good. Read the beginners glaze info on the web and ask all the questions you want, but try to be specific as possible.

You are going to have to make a few test tiles on your way to that perfect glaze, but there is no other way around this except blind luck... which I never have seemed to have :-)

Just posted this over on another forum

The problem with glaze software is that it might get you close to what you are looking for but it probably won't get you there. You said you want six basic glazes but that is too many. start out very specific as to what your first glaze should look like and then pick an already existing glaze that (supposedly) gives you what you want at cone 6 Then, keep tweaking this glaze ONE COMPONENT AT A TIME as everyone has already stressed. till it starts to look like what you want. Make sure that you have plenty of each material you use. Don't buy 1/4 pound of rutile for your tests and then run out and have to buy from possibly a new batch for your production glazes. Variation in materials can negate all your hard earned progress.

When you get the first glaze to your satisfaction... move on to the next.

 

Every time you run a glaze test that doesn't work out... ask for help here or over on http://cone6pots.ning.com/   There is at least a thousand years of expertise in glaze development between these two sites.

 

Don't get discouraged. stay focused on specifics. there is no single answer as to how to develop a glaze. If you are really going to do this... WRITE EVERYTHING DOWN.

 

And what is really cool, is that sometimes you do an adjustment but it doesn't look like what you wanted in the first place but it is absolutely beautiful in it's own right.  Now you have another glaze that you can use.

[Norm Stuart]

Making glazes is very much like cooking, except you can't taste along the way.

Don't underestimate how difficult it is to add the correct amount of each ingredient, and keep track of which ingredients you've already added so far.  It's dead simple, yet it's so easy to lose track of what you're doing.

Let's talk about accuracy.  Don't be distracted or tired.  We use inexpensive electronic scales accurate to 1/10 of 1 gram, and one gram scales which can weigh heavier amounts.  After adding each ingredient, I've taught people to weigh the entire batch.  If your total glaze should weight 500 grams and it actually weighs 507 or 489 (+/- 2%) then you've done reasonably well, but you can get better than that. 

If your 500 gram glaze weighs 413 grams or 560 grams you have something which needs to be thrown away.  Sometimes you suddenly "realize" it's underweight because you haven't yet added the Custer Feldspar - and it's possible that is the problem.  Unfortunately, it's far more likely that I have no real idea of what I've done wrong because of inattention. The same sort of casual inattention can also result in adding the correct amount of the wrong ingredient, the results of which become apparent with the first test tile.

Especially with our electronic scales, it's tempting to hit the TARE button and simply add the next ingredient.  This bad news for two reasons.  First, scales (including a triple beam scale) are less accurate weighing larger weights.  So adding 20 grams to the 480 grams already on the scale will give you a less accurate result than weighing the 20 grams by itself.  Second, if you add too much of an ingredient you may need the aid of a genie with magical powers to help you remove only the material you've just added.

When weighing material I either use my hand and fingers, or I use a "cut-off needle" to draw the material out of the cup.  I initially use the handle end to push material onto the scale, then as I get close I drag the material with the needle end.

I can't live in a respirator so I've divided our raw material into one pallet of high-silica material like talc, bentonite, silica and some clays and feldspars which require a respirator.  The other pallets contain material which we don't use a respirator for.  Once you add the high silica material, use the respirator until the glaze is wet. Before you take off the mask, wash your hands and arms which have attracted free silica.

This may sound obvious, but keep your raw materials well labelled.  This week our studio is currently dealing with glazes turning out wrong, which I think is the result of material contamination.  People have developed a habit of getting a container of raw material from the fifty pound bag, walking back to the tables on our patio, adding the amount they need, then returning to place the remainder, hopefully into the same bag.  There have been some errors.  So far I've found tell-tale grayish kaolin had been mixed in with the bag of yellowish silica.  I suspect there's other contaminated bags as well.  Adding salt in place of sugar doesn't make a very good apple pie.

When deliberately changing a recipe, I've suggested people swap the same amount of flux for a different flux, or a clay for a kaolin.  This can easily produce a glaze with the wrong COE, but you quickly get an idea of how changing ingredients changes the look of a glaze.

As Robert Coyle mentions, naturally mined products like rutile can be annoyingly different from batch to batch.  We started using a new five pound bag which acts far too much like titanium dioxide, rather than giving us streaks and streamers, perhaps because it's calcined "light rutile" or maybe it just a different batch.  Once we sort out the problem wiith "contaminated bags" of  other raw materials we'll buy another bag or rutile from a different supplier.

As you may already know from using commercial glazes, glazes will also look very different depending on how fast you let your kiln cool.  The authors of "Mastering Cone 6 Glazes" suggest a 150 F degree per hour cool between 1,800 F and 1,500 F, if I recall correctly.  We ultimately chose a much slower cooling for our default firing.  If your kiln doesn't let you control the rate of cooling, just know that your glaze will suddenly look different when fired in a different size kiln.

The boring uniformity of industrial ceramic products like china dinnerware represents a mastery of control over a large number of potential variables.  Some variation and inaccuracy is interesting and fun - too much isn't. I think the biggest disappointments people have experienced making glaze at our studio have resulted from making an unknown mistake and creating a beautiful new glaze which they have no idea of how to recreate.  Better to make intentional changes and keep careful records like Robert Coyle suggests.

As Robert Wedgewood's kiln journal read - "Trial 134, success!"

[Norm Stuart]

Dani - if you've managed to read the two responses you've already received to your question, then you have the patience needed to make glazes.

Some days are just not the right day for me to be making glazes, so I take a break.

[Dani Montoya]

Well alrighty then!

No magic glaze fairies will pop into my studio today! Thanks for the replies. I got a good chuckle Norm over the apple pie example because I once did that, i added a cup of salt to orange juice instead of a cup of sugar, but it wasnt really my fault. I was in a strang kitchen and they had the salt and sugar in cannisters that looked remarkable alike. The orange juice sucked and I learned right away to double check everything.

WhenI bought materials i think I bought enough to do what I needed, not 1/4 lb but 2 to 10 lbs. But as fate would have it, i never have exactly what I need!

My kiln is an older Cress, with a Kiln Sitter. I have yet to figure out how to hold a temp. In calling Cress and asking they say I can't. I did just get a pyrometer so maybe that will help. 

I think it is my note taking that I fall apart on. I make notes and when I go back to read how I did something i tend to think "what the heck does that mean"!

I do have a pottery teacher but for some reason he is reluctant to teach glazing. I have asked and asked. No go.

So...i will just go out there and keep playing! 

[Nadine Mercader]

Dani, I am not a chemist either but I have made some great glazes. The most important advice is what Norm said, ORGANIZATION, and record keeping. When I am weighing out materials I have the formula printed out with a check box and I keep notes as I go. I am fortunate because I don't have any others in my studio to mingle minerals together! I am unfortunate because I don't have anybody to warn me that I missed something! I also only make glaze when there are no distractions .
I keep my printed "recipes" in a binder and add notes after firing.
You can regulate a manual kiln if you are EXTREMELY patient. I used to fire manually but later bought a separate wall mounted computer controller. Check on eBay and you might find one. Your kiln simmply plugs into it with all knobs on high and it delivers power as required by the program, it is like a rheostat on a light. I look forward to seeing your pots!

[Dani Montoya]

Yes, Organization is critical, I can see that. I really haven't worked out a good system as yet. I do have a notebook I write things down in but it gets sloppy after a while and hard to read. I will work on this aspect. 

My Kiln is not really manual, but it is not digital either. I have a dial that allows me to fire faster or slower or "normal". It does it own thing and it does a pretty good job but I can not regulate the temperature to hold the temp. I tend to fire overnight because my studio gets too hot when its firing especially if it is already 100 degrees outside (It is nice to fire during the day in the winter though!)

I had not heard about the computer contoller. I will look into it . THanks

[Norm Stuart]

If you ever decide you want to add a computer controller to your kiln to replace the kiln sitter,  I think the Bartlett V6-CF for $489 is best for the money.

http://www.clay-king.com/kilns/olympic_kilns/electro_sitter.html

[juli long]

Dani,

I was in the same boat as you, no classes, overwhelmed, put it off, bad notes,(still can't figure out what the heck I was thinking, and can't read my own writing)!  Here is something I did to make it easier on myself.  I bought "GlazeCal". Your Glaze Makin' Cheat Sheet. Converts Glaze Recipe Percentages Into the Correct Gram Weights.  It  makes it doable for me then to make a 200, 500, 10,000, whatever batch size. It does all the converting and it's cheap.

The second thing that make my life easier, was buying an electronic scale.

After that, it took me an afternoon to set everything up, and make my first glaze test.  It took me that long because, I don't know, it just did, but I did it, and I haven't stopped since.

Juli

[Dani Montoya]

Thanks Juli. That GlazeCal looks pretty neat and helpful. Thanks for the heads up on it.

So i have started to play. I used up all my test tiles yesterday just adding colorants by themselves to see the color progression. I am not being all that accurate yet, but just wanting to see the actual color of a single colorant like chrome oxide green. 

So here I go!

[Norm Stuart]

Have fun Dani.

I found this webpage useful in combination with "Mastering Cone 6 Glazes".  The chemistry of glaze color.

http://digitalfire.com/4sight/properties/ceramic_property_glaze_col...

Chrome oxide used above 5% or so in many glazes leaves the excess precipitated out as small but expensive brown spots.

[Carl Cravens]

"...for Dummies" books aren't really for dummies.  They're often great introductions to their topics, written with an assumption that you know nothing about the topic.

I really like Bailey's "Glazes Cone 6" (there's a link on the sidebar here) as an introduction... the book is fairly short, and focuses on the balance between glass formers, stabilizers and fluxes, and examines what happens when you push each one to the extreme, etc.  It's very much about learning how to develop "good" glazes.  I've read it cover-to-cover twice.  I think it covers the basics that "Mastering Cone 6 Glazes" assumes you know something about, and they work well together.

[Kabe Burleson]

Hi Dani. Glazing can be a challenge. Record keeping by the motto " I'll remember and write it down later" still doesn't work well for me. I know better and sometimes I still do it. One thing that helps me in glaze testing for 100 gr batches is to write down the number or the name of the test glaze on a plastic spoon with a marker and leave it in the container forever. well at least until your done and have written down your results. A lot of time can pass between mixing up a batch, dipping it on a tile and seeing the results.  I hate to come back to my glaze table and find 2 or 3 unlabeled containers of glaze. "Oh I thought I would  remember." When you finish a test, pour the glaze and the spoon in a ziplock bag and label the bag. You can always reuse the glaze to see how it would look combined with another glaze, like a dip on a rim. makes it easer to do a test because it is already mixed. Label your test tiles with a mixture of bentonite and black iron oxide and water. paint it on with a fine brush like ink. it fires on the tile and will not come off. I use a number system to keep track of all my tests you can always change the name or number at a later time. computer glaze software is a must, I have insight so I can record notes in it. You only need to learn one thing at a time, it is the combination of one things that turns into knowledge. have fun. happy firing