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Fixing a nightmare to apply: add water or deflocculate??


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Hello. I am new to making my own glazes. The first glaze I've mixed from a recipe is beautiful to my eye but a nightmare to apply and I'm seeking some advice. The recipe: https://digitalfire.com/recipe/g1214z I've mixed a 3000g batch and added some Epsom salt solution to prevent it from hardpanning. I don't know why I did it, don't ask. :) Also, I forgot to measure SG before adding ES. I measured it afterwards and it was around a 1.43 mark.
Now it goes on REALLY thick even though it doesn't look thick when I mix it in the bucket. If I watch a bubble after I stir the glaze, it goes around for 2 counts and then has a bit of bounce back. This corresponds to what I saw in this video: https://www.youtube.com/watch?v=Ck_69eGJons
I have fired a few pieces since I first mixed the glaze; it doesn't run, even though it's really thick. It looks very beautiful @ Digitalfire's ^6 schedule https://digitalfire.com/schedule/plc6ds .
Yesterday I went to use it to glaze a few more pieces and walked away extremely frustrated. It seems to have gelled even more overtime (about 2 months), goes on in thick blobs (with minimal dipping time!), cracks and falls off.
What I've read so far here on CANforum on how to fix it presents two schools of thought: add water or add deflocculant. I have no idea which way to follow with this glaze! There's still a lot left of the batch and I don't want to ruin it.
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Deflocculate.  Never add magnesium sulfate just for fun, it will not end well.

That recipe has PLENTY of clay, there should be no need for any flocculants ever.  There is only one soluble ingredients and it's BARELY soluble (the frit).

 

Deflocculate carefully, a few drops at a time until it's the correct viscosity for you.

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With 20% clay you don't need to flocculate, and you've probably added too much Epsom salt. Deflocculate and see if you can get it to work. If you add water you'll have way too much water in the mix. Luckily 3000g is pretty inexpensive so if it doesn't work throw it out and try again.

Don't get locked into specific gravity, or at least not into one specific gravity. Figure out what works for you and your glazes and go with that. Some people like their glazes thick in the bucket, others like them more watery. There are no rules that have to be followed. And not all glazes behave the same, either. I've got one in my studio that needs to go on really thick to get good color development, so I mix it a lot thicker than the others so it can be applied correctly with one dip. I've got others that are very runny, so I mix them more watery so I can control their application better. In 28 years of making pots I've never once measured the SG of my glazes.

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1 hour ago, neilestrick said:

In 28 years of making pots I've never once measured the SG of my glazes.

I think this is one of those things that is partly dependant on how we learned to mix and apply glazes. I can't remember being taught to measure SG but had instructors to mix and demo the glazes so I learned through their experience. If someone hasn't had the guidance of more experienced potters I think that measuring the SG is a good way to dial in a glaze to a correct water to glaze materials ratio. I do measure SG when starting out with a new glaze, often because I don't bother to wait for it to slake down overnight so going by appearance alone can be deceiving. 

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2 hours ago, neilestrick said:

With 20% clay you don't need to flocculate, and you've probably added too much Epsom salt. Deflocculate and see if you can get it to work. If you add water you'll have way too much water in the mix. Luckily 3000g is pretty inexpensive so if it doesn't work throw it out and try again.

Neil, thank you. I'll try deflocculating. I'm a bit of a "by the book" nerd right now - it's like learning to cook when you follow a recipe to a T at first. But I'm sure I'll relax more as I gain experience and might forgo measuring anything, just throw stuff in a bucket and see what comes out LOL (kidding)

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1 hour ago, PeterH said:

Would you feel happier experimenting with a cup full first. You can then put it back into the bucket with an idea how much more deflocculant you will need for the whole bucket.

Great idea Peter, I might juts start with a cup of glaze to gauge how much I need to add.

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43 minutes ago, Min said:

 I do measure SG when starting out with a new glaze, often because I don't bother to wait for it to slake down overnight so going by appearance alone can be deceiving. 

The biggest mystery to me currently is how much water to add when making a glaze. I guess measuring SG partly helps me with this anxiety!

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30 minutes ago, 2Relaxed said:

The biggest mystery to me currently is how much water to add when making a glaze. I guess measuring SG partly helps me with this anxiety!

It entirely helps with that anxiety!

I use the webbing viscosity test, which is dipping my hand (gasp) in the glaze and spreading my fingers.  When the webbing settles at halfway down my fingers I know it's good.  If I need to adjust the water up after that I'll do it, or if I need to deflocculate I'll do that

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52 minutes ago, liambesaw said:

It entirely helps with that anxiety!

I use the webbing viscosity test, which is dipping my hand (gasp) in the glaze and spreading my fingers.  When the webbing settles at halfway down my fingers I know it's good.  If I need to adjust the water up after that I'll do it, or if I need to deflocculate I'll do that

Interesting, I haven't heard of the webbing test! Will try that, too.

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4 hours ago, 2Relaxed said:

Yesterday I went to use it to glaze a few more pieces and walked away extremely frustrated. It seems to have gelled even more overtime (about 2 months), goes on in thick blobs (with minimal dipping time!), cracks and falls off.

Just double checking, you used part calcined and part not calcined epk right?

4 hours ago, 2Relaxed said:

Also, I forgot to measure SG before adding ES. I measured it afterwards and it was around a 1.43 mark.

A few drops of epsom salts solution won't have drastically changed the SG. of 1.43  Try it out on some test tiles and see if they have the cracking issue. If there are cracks in the raw dried glaze there will likely be crawling in the glaze fire.  I'ld do what Peter suggested and try just a small amount of the glaze to test deflocculating with before doing the batch, or just put this glaze aside for now and start over.

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Posted (edited)
40 minutes ago, Min said:

Just double checking, you used part calcined and part not calcined epk right?

A few drops of epsom salts solution won't have drastically changed the SG. of 1.43  Try it out on some test tiles and see if they have the cracking issue. If there are cracks in the raw dried glaze there will likely be crawling in the glaze fire.  I'ld do what Peter suggested and try just a small amount of the glaze to test deflocculating with before doing the batch, or just put this glaze aside for now and start over.

Min, yes, I used part calcined kaolin and part regular EPK, per recipe.

I don't remember how much ES I added at the time of mixing the glaze. The fired pieces looked ugly right after glaze application but turned out near flawless after the fire. I just feel that after a two-month break, the slurry goes on thicker. It definitely cracks more and peels off once dry.

Edited by 2Relaxed
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Posted (edited)
2 hours ago, dhPotter said:

@2Relaxed regarding how much water to initially use - Mastering Cone 6 Glazes book suggest 3 ounces of water to every 100 g of dry material. This works out very well.

Thank you! That would then give an approximate  90:100 water to dry mix ratio, which makes sense to me.  And I even have the book, just need to actually open and read it!

Edited by 2Relaxed
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So, here's the report: I think I fixed this glaze's application issues last night.

I took 1/2 cup of the glaze and stirred in about 5 drops of the soda ash solution. Dipped a test tile and was very pleased to see a nice, even coat.  So I proceeded to do the same with the leftover batch in the bucket. Basically I had to eyeball how much soda ash to add, added a few pipette-fulls and kept stirring until I thought it looked right. (I know, very scientific approach). Dipped another test tile, but the glaze went on too thick still. So I kept adding soda ash little by little until the test tile finally looked good to me. It was kinda magical actually. :wub:

Scraped off the old glaze layer from the piece, washed it and it's drying now. I will dry it thoroughly and reapply this newly fixed slurry.

 

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10 minutes ago, 2Relaxed said:

Thank you! That would then give and approximate  90:100 water to dry mix ratio, which makes sense to me. 


when starting with the first use of a glaze I start with a water to dry mix at 60:100 weight ratio which will be somewhat thick.  I then add small amounts of water and test application on test tiles, then add some more, ... until the ratio approaches 100:100 ratio.  this will involve somewhere between 5 and 10 test tiles.  After these are fired and evaluated, I make a choice for the recipe and add the water : solids weight ratio as part of the recipe for that glaze.  For some glazes, I have two ratios because the test tiles show significant performance at different ratios.  

LT

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11 minutes ago, Magnolia Mud Research said:


when starting with the first use of a glaze I start with a water to dry mix at 60:100 weight ratio which will be somewhat thick.  I then add small amounts of water and test application on test tiles, then add some more, ... until the ratio approaches 100:100 ratio.  this will involve somewhere between 5 and 10 test tiles.  After these are fired and evaluated, I make a choice for the recipe and add the water : solids weight ratio as part of the recipe for that glaze.  For some glazes, I have two ratios because the test tiles show significant performance at different ratios.  

LT

Thank you. I understand the importance of thorough testing. If I were making glazes for others to use in a studio setting or if running a production, I would follow a similar approach. I don't know how feasible it is for someone like me who makes pots in spare time and runs glaze fires once every other month. Just not that kind of scale of operation, it'd take me months to evaluate each new glaze. :( I'm thankful for recipes that have a recommended water/dry mix ratios, and just hope to get lucky using the recommendations.

If anyone here makes pots in a situation similar to mine (very slow, very part-time), how do you guys go about trying out/developing new glazes?

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33 minutes ago, 2Relaxed said:

If I were making glazes for others to use in a studio setting or if running a production, I would follow a similar approach. I don't know how feasible it is for someone like me who makes pots in spare time and runs glaze fires once every other month. Just not that kind of scale of operation, it'd take me months to evaluate each new glaze.

Getting the glazes right does take time. I think it's rather common for people to understand that it takes practice to pull an even wall, hand build without warping, aesthetic considerations re form etc but glazing seems to take a back burner for how much time people are willing to spend on it. If you are methodical about it you can get a lot of glaze testing done in a full day. Firing a load of test tiles and small test pots might seem like a waste of both time and kiln space but it's far less irksome than having a load of pots turn out with subpar glazes. 

Re the ratio that @dhPotter gave you, keep in mind that a US gallon is smaller than the Imperial gallons we use in Canada.  1 Imperial gallon = 1.2 US gallons. For my glazes the ratio of 88.7 water : 100 dry glaze would be too thin but it might work for you. I'm glad you got your glaze deflocculated well.

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11 minutes ago, Min said:

Getting the glazes right does take time. I think it's rather common for people to understand that it takes practice to pull an even wall, hand build without warping, aesthetic considerations re form etc but glazing seems to take a back burner for how much time people are willing to spend on it. If you are methodical about it you can get a lot of glaze testing done in a full day. Firing a load of test tiles and small test pots might seem like a waste of both time and kiln space but it's far less irksome than having a load of pots turn out with subpar glazes. 

Re the ratio that @dhPotter gave you, keep in mind that a US gallon is smaller than the Imperial gallons we use in Canada.  1 Imperial gallon = 1.2 US gallons. For my glazes the ratio of 88.7 water : 100 dry glaze would be too thin but it might work for you. I'm glad you got your glaze deflocculated well.

Thank you Min. I'll do my best with lots of tests especially while I still have quite a few jars of commercial glazes to fall back to. They should help me fill the kiln and have more or less predictable results on wares that aren't just tests! I make test tiles when I'm in my studio for any length of time. Offcuts from handbuilding all go to tests. I hope to eventually fall into the rhythm of having plenty of test tiles in every glaze fire and I also hope to have refined my own glazes by the time I finally run out of commercial ones! :D

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33 minutes ago, Sorcery said:

See Thixotropic.

I don't know how common this is, but I know it's best to start with a possible fix that doesn't further change chemistry.

Change the simple things first.

Sorce

Sorry, I must be dense but this sounds really cryptic. As a beginner I'm having a hard time understanding hints like yours. :blink::lol: 

PS: I do know the term thixotropy. My question was what to do to fix the glaze. :lol:

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2 minutes ago, 2Relaxed said:

Sorry, I must be dense but this sounds really cryptic. As a beginner I'm having a hard time understanding hints like yours. :blink::lol: 

PS: I do know the term thixotropy. My question was what to do to fix the glaze. :lol:

It's ok, as an experienced layman I still don't understand what he's getting at.  Changing the chemistry is the only way to fix it.

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