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Nicky S

Hardening of glaze

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I mixed my glazes yesterday thru 120 mesh  sieve twice   And noticed crystallized pieces They had settled again this morning   ( 2 hours of grinding  work and sieved again ) Especially  2 out of 4 had settled Obviously not as much but still rather stiff Even though I added a bit of glaze thinner yesterday( deflocculant ) Could it be that they might be contaminated ???? This has happened before to same batches Any help would be much appreciated 

Thank you Nicky 

Edited by Nicky S

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Were these glazes that you had just made? They should not have crystallized pieces that quickly. Also, the deflocculant is probably contributing to the settling. If glazes are settling, then you need to add a flocculant such as epsom salts. Post the recipes.

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I doubt they are contaminated. I have never found this problem with commercial ones and have also had it on a few recipes. I have surmised its a recipe issue.  One thing that I think helps is let your glazes steep overnight after mixing but before meshing.

First off I may be breaking glaze law by stating such things but we use 80 mesh and I just do it once when I mix 10,000 gram batches (about 4 gallons in 5 gallon buckets) and then just use a drill mixer between glazing until a new batch is bought or mixed. We do not have any glaze issues on a couple of dozen commercial glazes and a dozen made from recipes. We s-can high maintenance glazes and since my partner likes a lot of glazes 2/3's of our glazes are commercial and I would like to move to 100%. I thought doing my own glazes was cool at first but tired of it. Money wise its just a non factor as glaze cost (once you have bought it) is such a low part of the overall cost. Labor is what matters not clay and glaze.  Besides I had to buy thousands of dollars of bulk ingredients and oxides to mix my own. OK I didn't HAVE to but small qtys of this stuff sometimes doubled the price per oz/lbs so I choose to and now I have tons of stuff I will unlikely use in a lifetime. To each his own but i wouldn't be a slave to glazes. Make a few and buy a few.   

Edited by Stephen

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If you're going through a lot of glaze, the cost of glazes can make a huge difference in your budget. You can mix your own glazes for 20% or less than the cost for commercial glazes. For a hobby potter it may not be worth it, but for someone who goes through many gallons of glaze a month, it's a huge difference in profits. For me it's a difference of at least $5000 a year.

The greatest advantage to mixing your own glazes is the control you have by knowing the formula. With commercial glazes you can't adjust anything. Aside from tweaking the firing schedule, it either works or it doesn't, and they don't all necessarily work on the same firing schedule. So craze, some melt too much at cone 6, others work best at cone 6, some need a soak, etc. It can be very frustrating. If you know the formula, you can adjust all your glazes to work with your clay body and your firing schedule.

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The only glazes I have had crystallize are ones that have lithium in them.  But that is after they have been in the bucket for awhile.  Not immediately.  I hope one of the glaze gurus can help you.  Do you have the recipe available??

 

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Without the recipes hard to help but flocculant would be first on list to try.

New folk often hesitant to post glaze recipes  secret stuff or the glaze has been purchased.

Mix ,slake over night then sieve or agitate depending on the glaze...

 

 

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Calcium boron crystals are definitely a thing that happens in a glaze bucket that's been sitting a while. They show up as flat sand-like grit in a glaze sieve. They come from ingredients like whiting and Gerstley borate, or even some Frits reacting with each other because they're in soloution. Calcium and boron are both common ingredients in many glazes at cone 6 and below. I recal from another thread that you said your were firing in earthenware ranges I think? Rather than breaking the crystals down by grinding, re-dissolve them in a little boiling water and add them back to the glaze bucket.

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@Callie Beller Diesel@Babs

@Magnolia Mud Research @Roberta12@neilestrick@Stephen@oldlady

@liambesaw

Thank you ALL for your  responses help and input.  All glazes are commercial .As I’m learning on my own I chose commercial exactly for that reason and thought cheaper and easier HA!All glazes where made up in small batches .I was advised to use a 120 mesh sieve for mixing glazes and 80 for stains . I only added the deflocculant recently as was “ hardpanned “from first mixing If they settle again Think I’ll just have to resort to buying new glazes 

Much appreciated Nicky 

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On 11/24/2018 at 1:49 PM, neilestrick said:

If you're going through a lot of glaze, the cost of glazes can make a huge difference in your budget. You can mix your own glazes for 20% or less than the cost for commercial glazes. For a hobby potter it may not be worth it, but for someone who goes through many gallons of glaze a month, it's a huge difference in profits. For me it's a difference of at least $5000 a year.

The greatest advantage to mixing your own glazes is the control you have by knowing the formula. With commercial glazes you can't adjust anything. Aside from tweaking the firing schedule, it either works or it doesn't, and they don't all necessarily work on the same firing schedule. So craze, some melt too much at cone 6, others work best at cone 6, some need a soak, etc. It can be very frustrating. If you know the formula, you can adjust all your glazes to work with your clay body and your firing schedule.

While our shop is not a hobby situation it is true we don't run through many gallons of glazes a month and I can certainly see that if you've found it saves you $400 a month after accounting for the extra time then making your own makes sense. As I said, my partner and I like a lot of glaze variety so making three dozen glazes was a huge undertaking and I had/have a lot of sunk cost in having plenty of materials on hand to keep stocked. I probably experienced it differently than some on the fuss because I couldn't take good advice I found advising just using the same base that fits your clay and then use oxides to color. Of course also lot of folks swear by only using a handful of glazes but that a different discussion  :-) I do think though that I spend gallon for gallon several times as much on the commercial glazes in actual cash but overall clay and glaze and firing is not a big factor for us, labor and marketing is and with the huge amount of bulk buying to make my glazes and the extra time it just lost its appeal to me. I also bought a bluebird mixer and mixed my own porcelain for a while but but dropped it for the same reason.

While I did a lot of research, installed glaze software and spend couple years running lots of test and doing what I needed to to get it right I still ended trying lots of cool recipes and ended up in recipe hell so I found it all to be way more fuss than just buying glazes. My in-house glazes do work fine and yes they are much cheaper than all of the ones I buy commercially and mix in-house. All of out pots  fire at cone 5 with a 20 minute hold to hit 6 with heat-work and a controlled cool-down to 1200. Any glaze that doesn't work with that firing schedule we would drop because with production and only 2 (7cf and 9cf) electric kilns we cannot spend time running different firing schedules for different pots. So far over the last decade the one's we buy and like to work with all do fine but I have dropped some of the recipe ones for being too fussy.

Good luck with the hardening glaze and don't let me discourage you from conditioning your glazes before every use, if it works for you than that's what counts.

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I'm also getting crystals from my low firing matt.  I understand it's the Gerst + Lith.  Also a very cold studio.

I use a hand blender every week before I use them. But then I read they disolve in hot water and wondered would it be OK to microwave the glaze? I'm using glass jars. Could this be hazardous and plain right stupid? 

Gherstly Borate 35      

Neph SY                 5        

EPK                          5       

Flint                       42      

Lithium Carb      8      

    

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5 hours ago, Grace london said:

@liambesaw Thanks Liam. My studio is cold and not at home. I'll try dissolving. But ideally I would like to make a big amount of each and not have that hassle each time. 

 Would Amaco gum or bentonite help you think?

Many thanks... G

Lots of things you can add to help with hard panning, not sure there's a lot to stop solubles from precipitating.  I see quite a few people adding 2 parts bentonite to help keep everything in suspension.  Veegum-t probably would work too, it's stronger.  I am not familiar with amaco gum, if it's really a gum I don't know that it would do much.  Epsom salts work too, like Mark said, but they are another soluble salt as well.  I use Epsom salts to thicken my white slip for decorating.  Personally I usually only mix glazes that have a good amount of clay to begin with so I don't have this problem

Edited by liambesaw

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OK.  It's not  hard panning, it's forming small crystals that float around.

I'll try the bentonite, then epsom like John Britt recommends in this: https://www.youtube.com/watch?v=0S_gbVkq378

Could be that there's just too much water? 

 A thicker glaze might have trouble forming crystals?

Many thanks

 

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23 hours ago, Grace london said:

Gherstly Borate 35      

Neph SY                 5        

EPK                          5       

Flint                       42      

Lithium Carb      8      

8 lithium carb is high. Have you done a test for shivering? Also, the recipe only adds up to 95, is there something missing? Are you using this for functional pots? Also, the alumina is low which means this won't be a durable glaze for functional ware. The cold is exacerbating how fast the crystals form and I would put it down to the lithium content. 

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I use it for sculpture Min, though I've been told it was safe. It's a beautiful low matt satin that I have found perfect for my decoration, quite reluctant to change as it works so nicely for me.  Nothing missing. Perhaps if I make it thicker it might not form cystals?? Thanks 

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