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JessHobbyPotter

Glaze application problem...

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I have just started making my own glazes, I purchased the raw materials and I used my friend’s hood in her lab to mix up some of the glazes.  I have bisqued pieces and the first coat of the glaze went on easily, BUT when I went to apply the the second coat it dried almost as quickly as the brush touched the pot, making it nearly impossible to apply a second coat.  It was as if the glaze crystalized upon touching like in a supersaturated solution, but the glaze was well mixed and not supersaturated.  This was with “Tin Foil II” and “MFE Turnidge”.  I did not wait long between coats… 

 

Any ideas would be appreciated.

 

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Hi and welcome!

Did you add anything to your glaze to aid in brush application? Any gums or glycerine, or Flotrol or anything like that? Most homemade glazes are good to go for dipping, pouring or spraying, but need additives for them to behave like commercial brushing glazes.

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Next time you mix up a batch, substitute about 1/3 of water with gum solution. The solution is easy to make:

Add 2 tablespoons CMC Gum and 1/4 teaspoon Copper Carbonate (as a preservative) to 1 gallon of hot water. Mix (it will clump up, and that's okay) and let it sit overnight. Then mix well with a stick/immersion blender until smooth.

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19 hours ago, neilestrick said:

Next time you mix up a batch, substitute about 1/3 of water with gum solution. The solution is easy to make:

Add 2 tablespoons CMC Gum and 1/4 teaspoon Copper Carbonate (as a preservative) to 1 gallon of hot water. Mix (it will clump up, and that's okay) and let it sit overnight. Then mix well with a stick/immersion blender until smooth.

Will the copper carbonate add Cu ions to the glaze and affect the color?  It seems like it will.  Is there a preservative you recommend that doesn't have transition metals?

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3 minutes ago, JessHobbyPotter said:

Will the copper carbonate add Cu ions to the glaze and affect the color?  It seems like it will.  Is there a preservative you recommend that doesn't have transition metals?

The copper is is such a small amount that it won't affect your glazes. The weight of a 1/4tsp of copper carb is about 0.5 grams. By the time that's diluted out in the glaze it's not enough to show up.

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19 hours ago, Callie Beller Diesel said:

Hi and welcome!

Did you add anything to your glaze to aid in brush application? Any gums or glycerine, or Flotrol or anything like that? Most homemade glazes are good to go for dipping, pouring or spraying, but need additives for them to behave like commercial brushing glazes.

I didn't.  today I tried adding a little (1/2 tsp, 7ml) of a saturated MgSO4*7H2O (epsom salts) solution.  That improved the consistency of the glazes, but not the brush-ability.  Which of the CMC gum, flotrol or glycerine do you recommend?  I don't have any of them, so any will be an additional purchase.

glaze application fail.jpg

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Epsom salts will help keep a glaze suspended, but it doesn't help it flow off a brush well. I would be worried that the application you've shown here would run due to excess glaze, or show every lump and bump if it's not one that moves around in the kiln much.

If I'm being honest, I have never really brushed glaze except for a time or two, as I was taught to dip and pour, that being the faster method. So I can't really give personal personal experience on this one. One of the benefits of mixing your own glaze is that you get to be able to adjust things to your own taste, and I think the addition of gums or binders is one of those things that you have to play around with to find exactly what you like. Glycerine is pretty cheap, and easily found at the drugstore. Flotrol you get at the paint store, and it's the stuff you're supposed to use in acrylic house paint if it's going on a bit thick. Probably would be kind of stinky burning out in the kiln. CMC goes rotten and stinks to high heaven, so you either have to mix it as you use it, or follow Neil's excellent suggestion about the copper. (That tiny quantity really doesn't show in a glaze).

OR

Depending on the amount of glaze you've mixed or have materials for, you could try dipping and pouring your piece. If you've just got the one glaze on there, you'll likely get better results. 

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Adding gum solution to a wet glaze will result in too much water in the glaze, and adding CMC Gum directly will cause a lot of clumping, as well as being difficult to calculate how much to use. I've used gum solution a lot, and it works very well. A combination of gum solution and VeeGum T is ideal, but VeeGum T is expensive. I'd just pick up some glycerine at the grocery for the glaze you have mixed up already, and see how you like it. Get some CMC next time you're at the clay supplier and try that for the next batch. It's cheap.

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On 8/20/2019 at 1:29 PM, JessHobbyPotter said:

I have the results!  I unloaded my first kiln today and about 1/2 of the pieces turned out with macro crystals.  Most with a modified Turnidge MEF glaze and a few with either Tin Foil II or Snair "gold stuff" modifies for Cone 6.  I like the Crazing with the Macro Crystals.  I wish the ring from the cooling cycle was more evident.  The is the same piece in the prior post.

 

 

190826smGr1903B1.jpg

190826smGr1903B1b.jpg

190826smGr1903B1a.jpg

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