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Trouble mixing dry glaze, much too thick!

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I am having a terrible time mixing a dry glaze. I ordered a  white dry satin glaze that should be fired to cone 5-6. 

I mixed 11oz of distilled water per pound of dry glaze (as recommended by the company that made the glaze), let sit overnight and sieved with an 80 mesh screen. Then when I was dipping pieces the glaze seemed a little too thick and was cracking as it dried, so I added water a little at a time until the cracking stopped. The specific gravity was in range and the viscosity seemed good. I let sit overnight again and the glaze is now super thick, like the consistency of yogurt. Do you know why this happened? Did I add to much water and somehow ruin the glaze? Is there a way to fix it? 

I contacted the maker of the glaze and they said to "just add more water" and that they did a test batch and it worked perfectly when adding the recommend amount of water. So, in my frustration I took 8oz of the glaze and added almost 8oz of water to it to get it thin enough to dip, and fired it and its crawling like crazy. 

What am I doing wrong here?

 

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Does the yoghurt glaze get thinner if you stir it? Might be thixotropic, can be a useful property for glaze application. 

Quote

Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick, or viscous, under static conditions will flow (become thin, less viscous) over time when shaken, agitated, sheared or otherwise stressed (time dependent viscosity).

 

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Thixotropic means that it gels when sitting still, but will re-liquefy when stirred vigorously. Don't add more water, as you discovered. Or only small amounts at a time. 

Edited by Rae Reich

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Chances are, the recommend amount of water is a general guideline for all of their glazes, not that specific glaze. Every glaze needs a different amount of water depending on what's in the glaze.

The thickening could also be due to some suspender or binder that they put in the glaze. Sometimes those can take longer to wet than the rest of the materials, hence the thickening even after a couple of days.

Stir the glaze well, and if it's still too thick, add water.

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Not sure if this helps but Neil seems spot on. When we mix studio glazes from scratch for dipping they usually require 100 - 140% water. Each glaze is different and we usually prefer to test and establish the best dipping consistency for each glaze, record it, then always use that amount of water for that glaze mix. If this is a brushing glaze it will likely contain gum Arabic or equivalent  to improve brush ability. Letting the glaze sit sufficiently for all the components to absorb the water added as Neil suggested is definitely step one followed by stirring and sieving and then of course simply adding more water per the manufacture until the glaze fits your use. Recording this for each specific glaze can help with consistency of result in future use of this glaze. If the glaze were to have settled to the bottom of the bucket in short order, this would be known as hard panning and there are simple reasons that this may happen and effective ways to cure  or improve the specific formulation. 

Not to get wonky on you but at our studio we develop studio glazes for use: (dipping, brushing, spraying) all required different amounts of water. Additionally as a studio glaze we like to determine durability which is fairly easy under UMF and also seek to formulate studio glazes that fire effectively from say cone 4-1/2 to 7-1/2 when possible for our cone six stuff. This helps eliminate many hours of frustration for students and helps save our shelves.

Edited by Bill Kielb

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Before adding more water It might be a good idea to check the specific gravity. Did the glaze instructions recommend a target to shoot for? You can measure a 100ml of glaze on a digital scale. A good starting point for dipping is 1.45 SG. When you measure the 100ml of glaze it should weigh 145 grams. If it weights that much then water is not the issue. If it weighs more than that, then you should add water, less than add more dry material. From there if it is still too thick, then it might be Flocculated. You can take a small amount, maybe a cup or so of the glaze and add a drop at a time some Darvan 7. If it gets to a good consistency at that point you can add the Darvan 7 to the full bucket. John Britt has a good video with more info on this.

 

 

Edited by OVMI_Designs

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@OVMI_Designs love that video.  I've watched it numerous times, despite the fact he never goes over any *new* information, when I rewatch it.   John just explains things so well, and his casual delivery makes watching his videos enjoyable.

 

In regards to the topic specifically, a glaze that cracks, when it dries, is definitely not a good thing.    Follow the tips listed above, and you should be able to get it dialed in.

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