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Glaze basics -- Deflocculating/Flocculating


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#1 bciskepottery

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Posted 19 December 2012 - 09:52 PM

Great video on glazes . . .

#2 yedrow

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Posted 19 December 2012 - 10:41 PM

Great video on glazes . . . http://www.youtube.c...d&v=fpQns05RdVU



Exactly what I've been needing to see, some visual references on flocculation and deflocculation. Thank you so very much!

Joel.



#3 Marcia Selsor

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Posted 19 December 2012 - 10:47 PM

Great video that explains how flocculants and deflocculants work. John is really a great teacher. thanks for posting.
marcia

#4 SmartsyArtsy

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Posted 20 December 2012 - 03:20 AM

He clarified these situations very well. Thanks for posting.

#5 Thrown_In_Stone

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Posted 21 December 2012 - 07:46 AM

Useful to know.

But, how do you know if it is deflocculated or if it has too much water in it?

#6 OffCenter

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Posted 21 December 2012 - 11:15 AM

Useful to know.

But, how do you know if it is deflocculated or if it has too much water in it?


Check recipe for neph. sy. If it has a good bit of neph. sy. in it then there is a good chance it is deflocculated instead of over watered, but only testing will tell for sure. Do as John suggested and add Darvan or sodium sil. to a cup or so of it and see what happens.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#7 VermontSarah

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Posted 12 June 2013 - 09:29 AM

I need help. I am pretty sure I have deflocculated glazes because they don't settle, look like gel, don't dry on a test piece of bisque, and have a lot of lithium and strontium in them. I've tested the specifc gravity and it is quite low meaning I'm sure I've added too much water to try to un-gel them at some point. I'm leaving them open to evaporate out some water now. The glazes are Steven Hill Water Color Green and Water Color Blue. I also have the same problem with Wright's Water Blue which I think has some similar ingredients. The problem is, no amount of Darvan 7 seems to help. That stuff gets expensive too. I have some fairly large batches so I don't want to throw them out, and plus, if I start over I'm afraid I'll have the same problem over time. In the future I will make much small batches. Any suggestions? Thanks in advance.

#8 VermontSarah

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Posted 12 June 2013 - 09:37 AM

I need help. I am pretty sure I have deflocculated glazes because they don't settle, look like gel, don't dry on a test piece of bisque, and have a lot of lithium and strontium in them. I've tested the specifc gravity and it is quite low meaning I'm sure I've added too much water to try to un-gel them at some point. I'm leaving them open to evaporate out some water now. The glazes are Steven Hill Water Color Green and Water Color Blue. I also have the same problem with Wright's Water Blue which I think has some similar ingredients. The problem is, no amount of Darvan 7 seems to help. That stuff gets expensive too. I have some fairly large batches so I don't want to throw them out, and plus, if I start over I'm afraid I'll have the same problem over time. In the future I will make much small batches. Any suggestions? Thanks in advance.




oops. I think I meant to say I have over-flocculated glazes, not deflocculated glazes.

#9 neilestrick

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Posted 12 June 2013 - 01:23 PM

I need help. I am pretty sure I have deflocculated glazes because they don't settle, look like gel, don't dry on a test piece of bisque, and have a lot of lithium and strontium in them. I've tested the specifc gravity and it is quite low meaning I'm sure I've added too much water to try to un-gel them at some point. I'm leaving them open to evaporate out some water now. The glazes are Steven Hill Water Color Green and Water Color Blue. I also have the same problem with Wright's Water Blue which I think has some similar ingredients. The problem is, no amount of Darvan 7 seems to help. That stuff gets expensive too. I have some fairly large batches so I don't want to throw them out, and plus, if I start over I'm afraid I'll have the same problem over time. In the future I will make much small batches. Any suggestions? Thanks in advance.


Do the glazes have a lot of Gerstley Borate in them? It tends to make them gel up.
Neil Estrick
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#10 VermontSarah

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Posted 12 June 2013 - 01:32 PM

No Gherstley Borate. Thanks.

#11 oldlady

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Posted 12 June 2013 - 01:56 PM

[



oops. I think I meant to say I have over-flocculated glazes, not deflocculated glazes.
[/quote]









sarah, at the bottom right of you original post there is a box saying "edit" that you can use to correct the original post to read what you meant to say.
"putting you down does not raise me up."

#12 Melanie Mann

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Posted 12 February 2014 - 01:49 PM

The first bucket you talked about - the one with the thick layer in the bottom.  I wasn't sure if this is the glaze you added the Epsom salt to or did you add the Esalt to just another glaze that was too thin?  Once a glaze has settled into a hard mass at the bottom of the bucket and you get it mixed up again, is there a way to prevent a glaze from settling out again?

 

 



#13 Norm Stuart

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Posted 12 February 2014 - 03:33 PM

Once you work Epsom Salts or Calcium Chloride into a hard-panned glaze it should stay suspended.

 

If it starts settling too quickly it either needs more of the above or it needs bentonite for the Magnesium Sulfate or Calcium Chloride to act on.

 

The first bucket you talked about - the one with the thick layer in the bottom.  I wasn't sure if this is the glaze you added the Epsom salt to or did you add the Esalt to just another glaze that was too thin?  Once a glaze has settled into a hard mass at the bottom of the bucket and you get it mixed up again, is there a way to prevent a glaze from settling out again?



#14 Norm Stuart

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Posted 12 February 2014 - 03:46 PM

Watercolor Green and Blue have no clay in their recipe, so would sink to the bottom like a stone, so the recipe tells you to add 3.1% bentonite which is a highly suspending silica clay.

 

Unfortunately, different types of bentonite all have different abilities to suspend.  So if you added 3.1% VeeGum you now have a glaze which is too flocculated holding too much water.  So in retrospect you need less bentonite.  I have this problem with all of Steven Hill's recipes, so he obviously uses a less suspending bentonite.

 

However, fire a test tile with what you currently have because this glaze is very fluid. If you find a way to apply it too thickly, you'll have a puddle of glaze.

 

You can deflocculate the glaze with Darvan, Sodium Silicate, or Sodium Carbonate, but this will not eliminate the excess water - unfortunately that you have to pour-off after it's settled (which is unlikely to happen with bentonite) or evaporate the excess water, or add more of the glazes's other ingredients without adding more bentonite.

 

We use VeeGum and as a result I always suspect any glaze recipe which calls for more than 2% bentonite.  You can always add additional bentonite to the glaze after it is mixed up.  The way to do this is add bentonite to a cup of boiling water and mix it with a stick blender.

 

I need help. I am pretty sure I have deflocculated glazes because they don't settle, look like gel, don't dry on a test piece of bisque, and have a lot of lithium and strontium in them. I've tested the specifc gravity and it is quite low meaning I'm sure I've added too much water to try to un-gel them at some point. I'm leaving them open to evaporate out some water now. The glazes are Steven Hill Water Color Green and Water Color Blue. I also have the same problem with Wright's Water Blue which I think has some similar ingredients. The problem is, no amount of Darvan 7 seems to help. That stuff gets expensive too. I have some fairly large batches so I don't want to throw them out, and plus, if I start over I'm afraid I'll have the same problem over time. In the future I will make much small batches. Any suggestions? Thanks in advance.



#15 cathgill

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Posted 15 February 2014 - 01:49 PM

John Britt's video is very good and this essentially self trained potter has really enjoyed "learning" after years of experimenting



#16 Benzine

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Posted 15 February 2014 - 02:17 PM

I keep watching videos like this one, as I find them very interesting.  I'm the type of person, who really likes to know how things work, and why they do the things that they do.  And as a teacher, it's nice to have an answer, whenever a student asks a similar question.

 

Hopefully, many of my questions are answered, when I get my copy of "Mastering Cone 6 Glazes".....And in case any of you are wondering, I just ordered the reprinted, black and white version, not one of the first color editions, people are asking ridiculous prices for.  I'm neither made of money, nor stupid. 


"Anything worth believing, is worth questioning"




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