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Rebekah Krieger

Making Your Own Glaze

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I have a largish kiln and a small test kiln with completely different firing schedules and the glazes look basically the same. I would say the small test kilns glazes actually look better but I have no idea on its firing schedule. I just turn it on full power for 7 hours and it gets to cone 9/10. It is great for testing glazes in because of its quick turn around.

 

When mixing up glazes I find it is good to leave them for a day otherwise you end up with quite a bubbly test tile. 

( I never listen to my own advice and have a lot of bubbly test tiles  <_< )

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neilestrick    1,381

I have a largish kiln and a small test kiln with completely different firing schedules and the glazes look basically the same. I would say the small test kilns glazes actually look better but I have no idea on its firing schedule. I just turn it on full power for 7 hours and it gets to cone 9/10. It is great for testing glazes in because of its quick turn around.

 

When mixing up glazes I find it is good to leave them for a day otherwise you end up with quite a bubbly test tile. 

( I never listen to my own advice and have a lot of bubbly test tiles  <_< )

 

Glazes in my three kilns can look radically different due to the cooling times. My baby kiln can be unloaded 5 hours after it reaches cone 6, the medium kiln in 15 hours, the big kiln takes 30 hours. A controlled cooling cycle is necessary for me to get the same results, which requires digital controllers. You can get an external digital controller, but it'll cost you $500 or more, so maybe not worth it unless you really want to do a lot of testing.

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Stephen    139

yeah both of ours have the same Bartlet controllers which I did intentionally so I could match them up for testing. Not sure I would want it any different since the test would not necessarily match results in the large kiln and for me the whole point is to get it down in the small kiln and then fire a large load based on those results. My test kiln is only 12"x9" (two sections with 2 shelves) and cost about $650ish. If I ever replace this one I will get something a little bigger so I can test a plate or charger in it.

 

I use it fairly often testing glazes and I can't imagine trying to test glaze samples in the larger kiln. The large one is not very big at 10cf but it seems like it is way too large to fire test tiles. I know it only cost a few bucks to fire it but there is also the wear and tear on it to just fire 10-12 test tiles or a cup or two with glaze combinations. I do it enough that I would even say it will eventually save me a set of elements in the large kiln and that would offset a big chunk of the cost of the test kiln.  

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I have one digital controller for the big kiln but it just has ramp 1 where you put in temperature and time then ramp 2 where you just input top temperature and a hold function. Not very fancy but I don't think my glazes are that fancy  ^_^ I would like to experiment with cooldowns but that will have to wait till I get cash to spare.

 

Why cant you just add a few test tiles into your larger kiln when firing a load? I find they fit in well in those small spaces I can never get to disappear. Just got to time tests with a glaze firing.

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Stephen    139

Hey High Bridge,

 

Certainly could save them and run in next glaze firing most of the time but that wouldn't work if trying firing schedules for particular glazes. Also my test are generally independent of larger loads and it is nice to just finish when I'm doing test by loading up the test tiles/pieces and run it.

 

...but of course your right you do not need a test kiln, just a nice luxury :-)   

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Aodenkou    1

In the YouTube video the gentleman was dipping the mugs dry.  YEARS ago when I too my first ceramics class I was told to quickly dip my pot in water to get rid of the dust and to have the bisque ware damp so that it did not take up too much glaze.

 

I set up my studio about 8 years ago and have been dipping my bisque ware in water prior to glazing.  QUESTION: Is it better to dip or pour glaze over dry bisque than wetting it as I have described?

 

Thanks in advance for any advice!

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Mark C.    1,807

I only dip or pour over dry pots except for some imbosed square plates where I want less glaze (thin)-then I spray them down with water mister.

Mark

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oldlady    1,323

dampen the pots if you plan to dip.  whoever you were watching may have a reason for what he does.  why change what has worked for you for so long?

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neilestrick    1,381

I find that if your pot is already wet, you have to have the glazes mixed pretty thick to get a decent layer applied. The problem is that really thick glazes don't go on as evenly. Also, if you make thin pots and they're already wet before you glaze them, they come out of the glaze totally saturated and take forever to dry. I glaze with my pots dry, and my glazes mixed to the consistency of thick creamy chocolate milk, and dip for a 6 count.

 

If the purpose of getting them wet before dipping is to make sure you don't get the glaze too thick, then just don't dip it as long and save yourself a step.

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bciskepottery    925

Your bisque temperature is also key. The higher the bisque temperature, the less absorbent it will be when dipping in glaze. The lower the bisque temperature, it will be more absorbent. Many community studios bisque high, like cone 05/04 to reduce glaze overruns from less experienced potters (the three second dip rule). Also, depending on the porosity of your bisque, you may need to adjust the viscosity of your glazes (thicker, thinner). Dipping/spraying in water will make the bisque less porous.

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neilestrick    1,381

Your bisque temperature is also key. The higher the bisque temperature, the less absorbent it will be when dipping in glaze. The lower the bisque temperature, it will be more absorbent.

 

Excellent point! I prefer my porcelain bisqued to 04, but like the stoneware at 06. I bisque everything to 04 to make things easier, and just dip the stoneware a little longer.

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Chantay    101

If Your just starting out with mixing your own glazes you need some items other than the raw materials.  A few of the items are:

sieves, large and test size

buckets with lids

mixer, I use a kitchen hand blender, you can use a drill (although I got plastic chunks in my glazes from the drill on the bottom of the bucket.)

brushes, spatulas, trays, etc..

fine particle mask

place to mix and to store materials

 

I'm sure there are more I can't think of at the moment.

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Stephen    139

I would also recommend exploring developing a good bases and then coloring them with oxides and stains. You will want both an opaque and transparent options. Use the recipe hunt for specialty glazes. I tried recipe after recipe and ended up when some very nice glazes. The problem was that the ones that made the cut as a group were all over the board and as a group kind of weird. Also you need to make a decision on how many glazes you are going to have and try to stay within this number by dropping and adding until you hit your regular lineup. It is very easy once you start trying this and that to end up with 25-30 glazes or more.

 

Also I have seen here and now adopted the advice of not dry mixing glaze materials. I found this to be problematic and always, no matter how hard I tried, ended up putting unwanted dust in the air by the time I finished mixing a half dozen batches. I now add to a bucket of water, about 75% of the water I want to end up with. We have recently started using a hydrometer to try and nail the right thickness of each glaze based on test firings. The thumb drip and '2% milk' consistency just was not cutting it.

 

Oh and I bought a really expensive digital gram scale from a pottery supply house that is great but I have found myself using a $20 target one as my go to and it seems to be just fine.

 

Good luck!  

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oldlady    1,323

one way to keep dust down is to work with a large scoop and a lid for the container you are putting the powdered glaze into.  put the scoop as far down in the bucket as possible and simply turn it over and remove quickly putting the lid on at once.  

 

doing all this outside with a fan running is better but we do not all have that luxury.

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bciskepottery    925

one way to keep dust down is to work with a large scoop and a lid for the container you are putting the powdered glaze into.  put the scoop as far down in the bucket as possible and simply turn it over and remove quickly putting the lid on at once.  

 

doing all this outside with a fan running is better but we do not all have that luxury.

You can also keep dust down by starting with some water in the glaze bucket with water and then adding the dry ingredients, then add the the rest of your water, mix, sieve, and glaze.

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Mark C.    1,807

Always mix dry into water for dust control-you can fine tune later with more water.

Mark

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Babs    386

Only ingredient I mix dry  is, if the glaze calls for a small percetage of bentonite, I mix this dry with the first ingredient in the glaze, do the rest wet adding the Bentonite and other at end;  slake the glaze o'night before sieving.

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oldlady    1,323

there is an advantage to mixing a base recipe dry and storing it dry.  once a bucketful is mixed, it lasts indefinitely.  when it is mixed with water, sometimes it is not used for some time and crusty stuff forms on the top or it dries out completely or gets so thick it has to be reconstituted anyway.  lots of labor or irritation.

 

the biggest advantage, to me anyway, is that if the base is available and if it was originally called "green", i am free to try the base with other colors at any time i want.  a ten gram (about a tablespoon dry) test of several mason stain colors lets me know which recipe is best for say turquoise or yellow without wasting lots of time or ingredients on something that won't work anyway.  and when i do want the green, i just put a couple thousand grams into the scale and add the proper amount of copper carb to get it.  that amount of glaze will get me through a lot of pots since i spray.

 

i guess this is what some of you get when you pay someone to mix dry ingredients and you add water when you get it in the mail.

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Glaze maker    0

At our local art center, we make all of our own glazes, have done so for years, and so our recipes are "tried and true."

Recently, however, we have been having some problems with several glazes, a few problems with texture and bubbling, but mostly color issues.

So we are now busy attempting to identify the source(s) of the problems. One thing we are considering is our chemicals.

My question is, can being stored in a hot environment have effects on glaze chemicals? We have recently been storing and mixing them on a balcony overlooking the glass blowers' hot shop. In the summer (this is Florida) it frequently exceeds 105 degrees up there when the glass people are going strong. Possibly higher - you can understand that I have not been tempted to check. :)

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bciskepottery    925

More likely are changes in the raw materials.  Are the problems coming after you've mixed new batches of glazes?  Have you started to use new bags of raw materials?  Industry changes raw materials and potters are generally the last to know . . . and only after firing a kiln full of glazed wares. 

 

The heat and humidty of FL will not affect your raw materials. 

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