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Tinkering With Commercial Glazes


Benzine

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I've used commercial glazes, in my classroom, since I've started teaching.  The majority of them are bottle glazes, with a couple I buy dry and mix with water.

Most of them work great, brush on very well, and keep a good consistency over time.  However, there are a few that cause me some problems.

 

One of the more popular glazes gets pretty thick, and cracks as it dries.  I used to just add water to thicker glazes, but as I learn more about glazes, I've discovered that it can make the problem worse.  

 

Another issue, is with the glazes I mix.  I follow mixing instructions, and the consistency seems great.  Then I go to use them, and they don't brush well at all.  They dry almost instantly, when applied, and like to settle in the container.  

 

I've added Espom salt to address the settling, which helped somewhat.  But I'm thinking of purchasing a couple other things, to see if I can improve things.

 

For the settling, bentonite seems to be advisable no?  I would think a commercial glaze, would have enough in it, but who knows.  I don't screen the glaze mixes, but thought about doing so.  What size mesh would be best?  I was also thinking of adding some type  of gum, to improve the brushability.  

 

In regards to the glazes thickening, I was going to try Darvan 7.

 

So my shopping list will be something like this:

 

Bentonite

Darvan 7

80-100 mesh screen

Vee Gum, CMC Gum or a Gum solution

Large bag Peanut butter M&Ms

 

How's my list look?

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Terry, it kind of depends, on what I'm in the mood for.  I can take either one.  The peanut butter in the M&Ms tastes more like real peanut butter.  That in the Reese's is a bit more like a whipped peanut butter product.  It's hard to go wrong with either.

 

I will give Reese's the edge, on luring and trapping aliens though.

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A beater stick thingie, Hand held blender for small quantities may be good enough without a sieve.

You may have to redo the stuff you add as I think Darvan and even Ep.S. don't last forever in the bucket.

Wouldn't the red fire out of hte M& Ms at quite a low temp? Not sure of the glaze melt temp of that one.

Heck if it's the true PB taste just add a jar to your list, empty you may use it to store your EP.S mixture. Be a drag to have to eat it so quickly, but you know...

 

 

http://ceramicartsdaily.org/ceramic-supplies/ceramic-glaze/using-glaze-additives-to-make-average-glazes-great/

This gives a bit of info Benzine, don't know if you've seen this.

No mentiton of M&Ms but.

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Bentonite - a good start when mixing new batches of dry glazes, usually 2% does the job. I've found bentonite harder to mix into already mixed glazes as you need to mix the bentonite with water separately and mix it to smooth consistency as it tends to clump when just put in water, and then add to the glaze, resieve, and use. Bentonite seems pretty benign . . . but you might want to test a small batch to see if there are any color impacts before committing to a large bucket.

 

Darvan 7 or Darvan 811(?) - great for adding to already mixed glazes that are too thick but you don't want to water down. Darvan does loose potency over time (as I'm told) and you only need to add a few drops at a time, so don't over commit.

 

80-100 mesh screen - I use 80 mesh for most glazes; 60 mesh for slips.

 

Vee Gum, CMC Gum or a Gum solution - I'd use these after trying the others or as an additive to small amounts of glaze for a single use. My small bottle of gum was rather expensive.

 

Large bag Peanut butter M&Ms - the most important item on the list, but I would not buy them at the Ceramics store; you'll get more fresh bags at the grocer. If adding to the glaze, you'll need a mortar and pestle so you can grind them to a fine powder before adding. In this case, stale ones are preferable as they powderize better than fresh ones that tend to be more creamy. A glaze/peanut butter M&M shake or smoothie can really give you an energy boost and get things moving. Or as toppings to a bowl of really stiff slip -- perhaps with the swirlies pattern from the other recent thread.

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why do you want to brush glaze on?  it seems to be the least efficient way of covering a piece.  commercial glazes have emulsifiers that cost a fortune so most potters do not have access to them.  

Ben is teaching high school. You do not want students dipping and pouring as then you have huge buckets of glaze. you want them sitting quietly with brush in hand putting on three coats of glaze on each piece.

TJR.

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I think a screen is better than no screen. 80 mesh is recommended for the dry glaze that I use. 100 a little slower, but you may get one or the other depending on what is available when you purchase the mesh.

 

I got a more even coat by quickly dipping the bisque in water and then brushing a slightly thinner mix 2 or 3X with a softer wide brush.

 

I added bentonite because it is not in the dry mix, it's cheap, hasn't screwed anything up yet, and with a mix before use it doesn't seem to settle. All of the dry mixes I have used settle a little bit overnight.

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Old Lady, as TJR mentioned, I like to have most my glazes brushable, as I am working with high school students.  They are accustomed to brushing with other media, so it works well.  Plus, thirty pint size jars of glaze, takes up a lot less space, than thirty buckets of glaze.

 

Babs, I do have a stick blender.  I just purchased it, so haven't used it to mix glazes yet, but it does work to make slip a great consistency.  Last year, I used a regular '70s blender to mix up glaze.  Thanks for the link as well.  I think I read that before, but it was a while back, so I did forget about it.

 

Clay Lover, the bottled glazes I use are all Amaco.  The one that likes to thicken, is "Old Pewter".  The students love it, as it's a nice dark metallic silver.  And it does interesting things, when layered with some other colors.  The dry mix I use, is from Continental Clay.

 

Bruce, thanks for all the suggestions.  I'll probably just eat the M&Ms straight up... Though not in my classroom, as we are a "Nut Free School"....

You're spot on about the gum.  CMC is sixteen bucks, for half a pound.  I noticed the supplier I use, sells a gum solution in a pint jar.  Would this be the same as just using a powder?  I would imagine it is probably more expensive in comparison, as they charge for the cost of mixing it.  But if I don't use much, then the cost of convenience might be worth it.  

So a 80 mesh screen is fine enough for most things?  

 

TJR, you are 100% correct.  Though, sitting quietly doesn't always happen.  My glazing area is relatively tiny, and in the same space as the wheels.  It gets tight enough back there, when I have people on the wheels, and students picking out their glazes.  I can't imagine how bad it would be, if they had to stand there dipping and pouring glaze.  The only downside to the bottles, is that since it takes a bit longer, a bit of a waiting list develops.  Heaven forbid the student, who needs said glaze color, goes and sits next to the person using it, who might not be their friend....  Why develop social skills?

 

Mug, thanks for the tips.  I've seen people post about moistening their wares, for a smoother application, but never tried it.  I notice the commercial mixes settle too.  A couple of my bottle glazes do too, but a good shake usually solves that.

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I'd go with the nuts as they are your strong suit. Maybe a suit with longer arms with straps in back. This may make the program go a bit sideways  but the students will improve the like with flashing red lights and a short ride to the green room.

Mark

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I never do anything other than brush glazes. I always use an polymeric brushing medium, rather than bentonite. The brushing medium, CMC or PEG or whatever forms a high polymer binder that literally sticks the glaze together on the surface of the pot, then burns off in the firing. I have never had trouble with flaking or any loss of glaze from the surface. I buy a ready made binder from the local clay store...probably mostly CMC... that has a mold inhibitor included. It costs more but is less of a hassle... no fermentation and stink.

 

The only problem I have with brushing, is that my students ALWAYS want to paint it on too thin. Once they learn to FLOW it on. the gazes look fine, and I don't need 5 gal pails of every glaze.

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Sorry, I don't have that information. This is a local product that I have not made myself, but it is probably CMC with some type of fungicide added. I suspect maybe paraformadehyde. The point is, if you have any kind of high polymere binder... even pvc, It will hold the glaze on the surface of the pot better than bentonite can ever do.

 

here is a link to some ideas in clayart. http://www.potters.org/subject107541.htm

 

There are many commercial products available. most can be used at about a 1-25 addition level.

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Are you sure that the glazes that you are purchasing dry and adding water to are meant to be brushed on? 

Probably not, but that's why I am going to add a brushing medium.  The big problem with the dry mixes is, that they love to settle.  They also have a marble look, when you look at them.  Both things, seem to indicate some deflocculation.

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