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Glaze Runs Good Kind Not Bad


AndreaB

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Guest JBaymore

After you have applied the glaze (in general) to the top part of the form, go back using a small brush to really thicken up the glaze layer at the bottom area of the end of the previously applied glaze in the spots that you want the runs to happen. 

 

Also "break" the linear ending line of the glaze layer slightly downward (couple of mm will work) in the spot the run should happen with a bit of the glaze.

 

"Happy accidents" are not always accidents. ;)

 

EDIT:  See here at bottom of form... those are not "happenstance": gallery_1543_134_4274355.jpg

 

best,

 

.......john

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Hey,

I could think of a few ways of controlling glaze runs.

First look at the form of the example. The cup starts wide, then narrows to speed up the glaze flow. The body is expanded creating a shoulder to slow down the glaze flow. The decorative grooves are actually "speed bumps" to keep the glaze under control before reaching the kiln shelf.

1. Use John's method and add extra glaze after dipping

2. Apply extra glaze before dipping, and dip over it.

3. Dip the first coat just below the handle, sponge off top half and allow to dry. Then glaze again. That puts a single coat on top and a double glaze on the lower half.

I'd probably go with number three, simply because its a little more work.

And you'd wind up with a two tone color like the example.

But it would stop me from making up 10 to 20 exact bisqued copies and experimenting.

I prefer swirled glaze runs (like on my cistern), which I glaze, then hold at a 45 degree angle and add runs with a turkey baster.

Make a list of all the possibilities you can think of, then experiment.

Have fun!!!

Alabama

 

Post script: the base of the vessel needs to be as wide as the neck of the cup

and I'd define it with a small lip as extra insurance against glaze to

shelf contact..

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I agree with John that random results are not really desirable.  Runny glazes scare me for that reason.

 

You can get good glaze run effects just by using a stiff glaze with the right surface tension.  Apply the drips during dipping (either through a deliberately sloppy dipping technique or with a slip trailer or whatever).  You don't get some of the effects of a properly runny glaze, but the effects are along the same lines. Applying a runny glaze over the stiff one can help get variegated effects and breaks. The runny glaze will tend to run along the drips from dipping and the stiff glaze will help to keep the drips from moving too far.

 

I don't know how orthodox a technique this is, but I've had good success messing with it and I feel it's safer than just letting it run.

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The thought process in glazing shouldn't always be working out how to get something like this. See what you get and try to accentuate the aspects you like. There are many variables to guess at when looking at a picture.

 

Five factors to consider:

There are sets of two stable glazes that when applied together will be more fluid.

Applying a thick layer of glaze may cause runs.

A low-alumina glaze will flow more.

So will one with more flux (feldspar).

The other -huge- factor is the firing schedule. Longer soak times give more time at the lowest viscosity.

 

Use catchers to prevent damage!

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Guest JBaymore

 .............that is where I would start with the chemistry and see what makes them flow.

 

Drop the # of mols of alumina.... that will make them run given some time at the peak temps or a slow profile to get there.

 

best,

 

.................john

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All good advice above.

 

I would only add that if you want the effects of a runny glaze, sometimes you have to take a risk that the run will make it to the bottom of the pot.  If you set the piece on a little tray of kaolin, it will be easier to deal with any glaze that makes it past the foot.

 

I love the look of a runny glaze, personally.  To me it is tangible evidence of the kiln's heat... that turns powder into glass and raw clay into something that can survive a thousand years unchanged.

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