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Shelly M

Glaze Gel Fix

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 I have a glaze recipe that gelled???  in the bucket. I am very new at making my own glazes so I think gelling is what the problem is called. Right after I restir and try to use, it sort of clumps together (flocculates?) in a slimy mass. I am wondering what I can add that will correct the problem. I have sodium silicate on hand. Here is the recipe, perhaps I should change the recipe instead of adding something to correct it?  Thank you in advance!

Dolomite                                          5.85

Gerstley Borate                         13.37

Whiting                                              8.10

Zinc Oxide                                        3.90

Custer Feldspar                          44.39

EPK Kaolin                                         4.88

Silica                                                    19.51 

                                                             100

add:

Zircopax                                                  10

Granular Rutile                                       3  (added to create speckles in the glaze)

Bentonite                                                    1

     
     
     
     
     
     
     
   
     
     
     

 

Edited by Shelly M

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I don't know enough about mixing glazes, to be able to tell you if the ingredients need to be adjusted, but Darvan or Sodium Silicate would help Deflocculate the glaze, making it flow better.

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The Gerstley Borate will gel, but it's not particularly high in Gerstley. Did you sieve the glaze after mixing? Are you sure it doesn't just need more water? Any chance you added too much bentonite? Have you test fired to the glaze? That will rule out if you messed up any of the measurements, for the most part.

Edited by neilestrick

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I wouldn't usually put bentonite in a glaze with gerstley borate in the future.  The only exception is maybe if there is 0 clay and a low GB number.  It doesn't usually need it. GB gels the mix so good that everything is always suspended well. But 13GB with 5 clay is not going to need bentonite. That being said I haven't mixed up this recipe and maybe it needed it, but look at it I don't really think it would. 

At this point you should probably add tiny bit of darvins or sodium silicate along with water. If you add to much water there is a chance you will over saturate the glaze and then it will just be useless until you let some of that water evaporate, and then you start getting into areas where it might be hard to replicate the consistency next time.

So I would do something like add 1ml of darvins/ss and then mix. Then add a little water and mix. Keep doing this until the bucket doesn't instantly gel. They let it sit for an hour or two, then repeat again. I have no idea how big your batch of glaze is and if you have been keeping records of how much water you have added to this point, but its worth noting that everything good in ceramics and glaze mixing in particular is about accuracy when your starting out. Nothing is more frustrating then next time you mix this glaze it isn't the same and you liked it the first time.

Good luck.

 

Edited by Joseph F
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Might be an idea to measure the specific gravity of the glaze then add the water. A very rough ball park figure for specific gravity is 1 point 5. It only takes a few minutes to do and if you are new to mixing glazes it’s probably a good idea. Doing a sg weight will get you to approximately how much water is needed for this glaze. Don't really think you need to defloc a glaze with just this small amount of GB but get the specific gravity into the 1 point 4 to 1 point 5 range then see if it still feels too gelled and go from there. Definitely sieve the glaze. 

Different ways to measure sg, one method using a scale and measuring cup here.

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On 9/14/2017 at 4:01 PM, Joseph F said:

I wouldn't usually put bentonite in a glaze with gerstley borate in the future.  The only exception is maybe if there is 0 clay and a low GB number.  It doesn't usually need it. GB gels the mix so good that everything is always suspended well. But 13GB with 5 clay is not going to need bentonite. That being said I haven't mixed up this recipe and maybe it needed it, but look at it I don't really think it would. 

At this point you should probably add tiny bit of darvins or sodium silicate along with water. If you add to much water there is a chance you will over saturate the glaze and then it will just be useless until you let some of that water evaporate, and then you start getting into areas where it might be hard to replicate the consistency next time.

So I would do something like add 1ml of darvins/ss and then mix. Then add a little water and mix. Keep doing this until the bucket doesn't instantly gel. They let it sit for an hour or two, then repeat again. I have no idea how big your batch of glaze is and if you have been keeping records of how much water you have added to this point, but its worth noting that everything good in ceramics and glaze mixing in particular is about accuracy when your starting out. Nothing is more frustrating then next time you mix this glaze it isn't the same and you liked it the first time.

Good luck.

 

Great input. Thank you! I mixed 1000g of this batch so not too much to toss out if I can't fix it. I'll  try the sodium silicate as that's what I have available.

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On 9/14/2017 at 4:24 PM, Min said:

Might be an idea to measure the specific gravity of the glaze then add the water. A very rough ball park figure for specific gravity is 1 point 5. It only takes a few minutes to do and if you are new to mixing glazes it’s probably a good idea. Doing a sg weight will get you to approximately how much water is needed for this glaze. Don't really think you need to defloc a glaze with just this small amount of GB but get the specific gravity into the 1 point 4 to 1 point 5 range then see if it still feels too gelled and go from there. Definitely sieve the glaze. 

Different ways to measure sg, one method using a scale and measuring cup here.

Thank you Min. I will definitely sieve the glaze then measure the specific gravity.

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