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More Questions About Glazes


jolieo

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So I have decided that I will order small amounts of the glaze making chemicals, mess around w them for a bit and see what I like. I am getting the recipes from the mid fire john Britt book. So I had the flu( was going to do the order Friday or Saturday but too sick) and it is taking a minute to get a clear head. I was reading the glaze making part again, and as usual some of what Mr Britt is saying is finally sinking in.

If I dip , brush or spray, the consistency is different for each application. So I make the glaze, do all 3 on test tile -making sure to not which is which.and see what it does and adjust, right.

I do not want to do the dipping layer thing: I want to do under glazes and stains. So I basically want clear or translucent .the underglaze so and stains will have an effect on the glaze. I am not trying to have a line ohf predictable results, more either a painterly effect, or a very minalmalistic effect.

I am not necessary going to know what is I am going for until I start going for it.

So I was not thinking of the stabilizers , the none iron bentonites, deflocculants etc per se. My shopping list was going to be of the ingredients for maybe 7 glazes.

Do I add all these extras , just in case ? Or I am definately going to need them.

Also I am a little confused but Mr Britts passage on how thick the glaze ought to be when applied to the pot. The thickness of a dime. But some is absorbed by the bisque ware, how can I tell how thick then? Is there clarity around this issue? Or is it test and take notes? Do you know by using a tool that measures precisely or is it by eye? Because I didn't intend to buy that tool, or do I really need it?

Also he mentions different absorbtion rates for different bisque temperatures. Then he says that one should bisque to a consistent temp, keep work to a consistent thickness, in order to have consistent results.but then is it worth messing about for me to find what temp I like to bisque at? So as a newbie who is into playing with aesthetics , do I do 3 different bissues, put my 7 glazes over them and test . Or do I do 3 different bisques , put my under glazes and stains under all 7 of my glazes? Or do just one bisque,w the 7 glazes, or one bisques w all colors and 7 glazes.

Do they have to be tiles ? So boring . I know for reference sake, but I feel like I won't be keeping these references, a lot won't work right and will have to be messed with.

How is it done by you?

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Not sure if I understood your questions, but if you are asking about bentonite, yes, I would get some of the white firing kind (or macaloid or veegum) if you are planning on doing clear/transparent glazes, you don't need a lot, 1/4 lb would be plenty for now. I would also get a tiny amount of epsom salts, this might be cheaper at a drugstore. If your glaze is low on clay the bentonite will help it play better. I don't use deflocs as often as flocs, would probably skip the deflocs for now.

 

As for glaze thickness when Britt talks about the thickness of a dime he is talking about after the glaze is dipped and dried on the bisque. Easy way to see thickness is to take an unfired glazed test tile and scratch through it. Do 2 tiles and keep one unfired for reference. When you do your tiles do 3 different thicknesses, 1 dip over entire tile, then when the sheen is off the glaze redip it about 1/2 way down the tile then do a third dip on one upper corner of the tile. (I like using tall narrow tiles, leaving a wide unglazed strip to allow for runs at the bottom of vertical tiles)

 

For bisque firing just fire to whatever you usually would, probably 05 - 04 and stick to that for future loads so each load of bisque is about the same porosity. So for your first round of tests I would do the 7 glazes without underglazes or stains plus the 7 glazes on another set of test tiles with the underglazes or stains. (some stains have an effect on glaze melt)

 

If a glaze looks okay on a test tile and it's for functional pots I craze test it (320 oven then plunged in cold water X 3 cycles then rub sumi / India ink on it to see if its crazed). If it passes my craze test then I use it on a mini pot to see what it really looks like. Seems a glaze can look great on a test tile only to look meh on a real pot. Getting a well fitting clear sounds easy but I've found it one of the harder things to do.

 

I would also suggest starting a code of some sort that works for you to mark your tiles with and keep good records.

 

Hope you are feeling better :)

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Thanks Min , went to dr, ended up w mucinex d , miracle stuff , I feel very much better.

Ok I am going to post my little order here and correct me if I am missing something please( I have to come back with it)

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So here is the dry ingredient list that will make a lot of glazes from John Britts book

Custer feldspar. Nephe. G200 feldspar ( do I get the new? Idk). Fh feldspar

Silica ( but which mesh?) Wollastonite Fits 3134, 3124, 3195. Gerstley borate

Talc. Whiting. Kaolin. Bentonite

Strontium carb. Zinc lithium carb( can I replace w something cheaper?)

 

Do I need alumina hydrate or oxide?

Magnesium carb?

All Frits?

Should I try eps?( it's local, I feel loyalty)

What ball clays?

 

I was going to get iron oxide the 3 colors, a rutile( which one?) zircopax plus

 

My list includes 2 full shelves, 1 half shelf , 3 each 1/2",1",2",3",4",6" kiln posts

Cones o4,05,06

Cones 4, 5,6,7

Banding wheel,safety glasses,test sieve

A few mason stains

 

Please tell me if I am missing anything

Thanks jolie

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Actually, I would suggest a couple changes to your list.

 

Gerstley Borate can be subbed with 3134 most of the time with glaze calc program. If you post the recipe using it here someone could rework it for you. I still use Gerstley Borate in some recipes but you can probably get away without it and some of the problems it causes. On the other hand it's cheap so no biggie if you pick some up and try it.

 

Lithium Carb can only be subbed with spodumene but again you need to change the recipe to fit it in. I would go with the lithium carb as you will only need a few percentages at the most in a glaze.

 

Silica, 200 mesh is fine for most glazes. Some glazes call for 325 mesh to help reduce crazing. 

 

For iron oxide and rutile there can be a great difference in quality from different suppliers. I order all my colouring oxides from US Pigments. For the iron the high purity red one and for rutile the light one. 

 

Alumina hydrate, for making kiln wash.

 

Not sure what eps is? Typo for epk? Yup to that. 

 

There has been a bit of confusion with the replacement for the old G200, I would talk to your supplier and see what they are carrying in your part of the world. 

 

Ball clay, I'm on the other side of the continent from you so I don't know what's available for you. Again, I would go with what the local place recommends.

 

I would also pick up some Minspar and dolomite and or talc.

 

For kiln posts I would suggest getting more of the height of the pots that you make the most of. You will need 3 of the 1/2" ones to raise your bottom shelf off the floor with. You will likely need the bottom and probably top shelf to have a wider space between shelves than the middle of the kiln, unless you have a 3 zone controller. So, taller posts needed for the second shelf up and and one at the top. I use broken bits of kiln shelves for adding a titch more height so would probably get more of the 1/2" ones. You need to have 1 element between shelves at a minimum so no point in getting a lot of short posts unless you are using them to increase the height of other posts.

 

For bisque firing I would just get the 04 cones if you have to buy them by the full box. If you can buy single ones then I would get a few of the 05 and 07 and use those just until you are comfortable with your bisque firing. It doesn't need to be as exact as the glaze firing.  If you are firing ^6 then I would get 5,6 and 7 but skip the 4.

 

I wear nitrile gloves when handling glaze materials. If you don't have one already then a definite must is a well fitting respirator/mask with a P100 rating.

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WOW Min thanks so , so very much. I will do as you say. The respirator is not sold by the shop I am buying from so I would appreciate an exact model because there are so many versions I am getting confused.

Really thank so much

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I disagree about 3134 being able to substitute for Gerstley. More often than not I have found that it won't work. It usually only works on glazes with small amounts of Gerstley. Get Gerstley or Gillespie Borate. For Frits get 3110, 3124, 3134 and 3195. Don't worry about white dolomite. Just get the cheap stuff. You'll be using small percentages and it doesn't have enough iron in it to affect the glaze. I never use mag carb, but use dolomite a lot. I very rarely use ball clay in glazes. I've also never had a problem with cheap red iron oxide or rutile.

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WOW Min thanks so , so very much. I will do as you say. The respirator is not sold by the shop I am buying from so I would appreciate an exact model because there are so many versions I am getting confused.

Really thank so much

 

Get a respirator with a P100 cartridge.

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I disagree about 3134 being able to substitute for Gerstley. More often than not I have found that it won't work. It usually only works on glazes with small amounts of Gerstley. Get Gerstley or Gillespie Borate. For Frits get 3110, 3124, 3134 and 3195. Don't worry about white dolomite. Just get the cheap stuff. You'll be using small percentages and it doesn't have enough iron in it to affect the glaze. I never use mag carb, but use dolomite a lot. I very rarely use ball clay in glazes. I've also never had a problem with cheap red iron oxide or rutile.

 

I guess this goes to show why glaze recipes don't travel well. Can't get Gillespie Borate here, is it worth ordering it in do you think? It was actually bentonite not dolomite that I think is worth getting the white kind of. Again, it could be supply, same for the iron and rutile. Sounds like your supplier carries better quality stock than mine. 

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I disagree about 3134 being able to substitute for Gerstley. More often than not I have found that it won't work. It usually only works on glazes with small amounts of Gerstley. Get Gerstley or Gillespie Borate. For Frits get 3110, 3124, 3134 and 3195. Don't worry about white dolomite. Just get the cheap stuff. You'll be using small percentages and it doesn't have enough iron in it to affect the glaze. I never use mag carb, but use dolomite a lot. I very rarely use ball clay in glazes. I've also never had a problem with cheap red iron oxide or rutile.

 

I guess this goes to show why glaze recipes don't travel well. Can't get Gillespie Borate here, is it worth ordering it in do you think? It was actually bentonite not dolomite that I think is worth getting the white kind of. Again, it could be supply, same for the iron and rutile. Sounds like your supplier carries better quality stock than mine. 

 

 

That was a typo. I meant white bentonite. I think it's worth the money for clay bodies, but not in glazes.

 

I'm a big fan of gerstley substitutes, of which there are several. I can get Gillespie so I use it. I know Laguna and a couple other suppliers also make substitutes.

 

In regards to the iron, it could also be that because I buy it in 50 pound bags it lasts me a really long time, so I don't see differences in purity.

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Lithium Carb can only be subbed with spodumene but again you need to change the recipe to fit it in. I would go with the lithium carb as you will only need a few percentages at the most in a glaze.

 

Min gave you excellent advice, though I will point out that you can get lithium by using petalite.  I mention this only because my longtime Standard distributor made me a gift of a 50 lb bag last weekend, so I'm trying to come up with glaze recipes to use it.  I don't think I can just sub it for feldspar, because it's such a low-expansion material, but there must be something I can do with it.
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Lithium Carb can only be subbed with spodumene but again you need to change the recipe to fit it in. I would go with the lithium carb as you will only need a few percentages at the most in a glaze.
 
Min gave you excellent advice, though I will point out that you can get lithium by using petalite.  I mention this only because my longtime Standard distributor made me a gift of a 50 lb bag last weekend, so I'm trying to come up with glaze recipes to use it.  I don't think I can just sub it for feldspar, because it's such a low-expansion material, but there must be something I can do with it.

 

 

Oops, my bad, forgot about petalite. 

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Wow thank yo very much Neil, I am taking notes. Thanks Rayalridge, I will try petalite as well.

My list is with the ceramic shop , they have one grit 3269 - it doesn't have a description blurb?anyway I'll look k it up later..

What is gerstlsey borate's issues?( I feel like I'm gossiping)

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if you can get C&C ball clay, do it.  it is a white ball clay, the usual stuff from Old Mine #4 is brownish.  C&C is better if you make a white or clear and need it.  check out prices.  yes, if you are close enough to drive, it is simple to re-stock but the reason you might buy a large quantity, 50 lbs at a time, is that you will know that what you are using is the same as it was the last time.  and buying by the whole bag is cheaper by the pound since there is no labor involved in weighing out tiny bits at a time.  

 

 i do not know your supplier, call them to see if you need to warn them about coming in with a big order for tiny bits of stuff.

 

have never had any problem with gerstley borate.  no gossip from me.   get silica 325.  if you buy zinc oxide, ever, get it in powdered not granulated form.  do not buy anything granulated unless it is silica sand.

 

setting up a glaze kitchen has been discussed before, lots of info if you can retrieve it.  did you mention getting a sieve?   i know the totally educated people want to use a 100 mesh or at minimum an 80 mesh, but you can do perfectly well with a 60.

 

there are several approaches to this stuff, the people who work it all out in advance and know to the decimal point exactly how a glaze should react and those of us who try different recipes with the idea, "wonder if this will work?"    somewhere, you will find your place.

 

what is the reference to a grit 3269?????

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Thank you oldlady so I did not notice autocorrect- it was frit, not grit,3369

I am testing glazes from John Brits book in hopes that I can find one or two that I like or come out well.

This is important to me because I like the feel of satin and matt glazes so very much. And I had no clue that those glazes were such problem children. The reactive glazes like coyote look fun , I am also in need of controlling my color. Idk if I will ever buy in bulk, I would have to really produce a lot: the humidity here will invade climate controlled spaces. Turns a lot of dry ingredients to rock. So I probably will be buying smaller amounts . I am also unsure if I am going to dip,pour , brush or spray. So I will not be sure of the specific gravity I need. I know , I know test test test. Thanks again

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Jolie, don't worry so much about the humidity.  We're on the Gulf, just a couple blocks from the bay, and I have no problems with glaze ingredients absorbing water and caking up.  I have buckets and bags of dry materials that have been in my glaze room for 25 years and they still flow freely, including kaolin and ball clay.  My glaze room is not climate controlled (gets pretty hot in summer.) It's only a problem if water rains directly on them, and even then you can still use the materials once they've dried out completely.

 

Glaze ingredients are not like plaster or cement. 

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Guest JBaymore

Remember to request copies of the MSDSs for all of the raw materials that you order.

 

Here is a good half face respirator that is quite comfortable because of the material it is made out of.  Note the SIZES.  For most women, the SMALL seems to fit well.

 

http://www.emedco.com/north-7700-silicone-half-mask-respirator-re232.html#viewoptions

 

Here is a cartridge for it that will have you covered for just about anything you might ever use in a studio:

 

http://www.emedco.com/north-defender-multi-purpose-respirator-cartridges-rm563.html#product-features

 

Use the SKU: RE234

 

best,

 

..........................john

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Roberta I wish I did too! (Where DO ou live?)

Ok which ones did you do? Can I see pictures? He had some exotics in there, did you do any?

John thank you for respirator. Really right it is really helpful not to be given too many choices, I get lost in the trees, or is it the forest....

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