[Clayart] Ron Roy fake maiolica problem (Bryan Johnson)

[Jeff Lawrence]

Bryan wrote:
I?ve tried this recipe and love the results but it has pin holes,
crawls, leaves running drips and is very powdery. Any suggestions to
correct these problems?

Hi Bryan,
When I've had these problems, I've found the following to help:
- CMC is a big help, though a pain to mix in retroactively; best is to mix
it into the dry ingredients, then sieve the slop, but with a wand mixer and
a couple of days to settle, you can make a CMC syrup to add to existing
batches (start with hot water and give it a couple of days to de-air). If
you add dry CMC to a wet batch it creates globs of floating gelatin.
- Ball milling is a great way to disperse things like zircopax and
wollastonite, which cluster together to cause mischief even sieved 80m.
- Make sure glaze is thin enough so it can mate well with your bisque; for
my white glaze, I like about 1.41 but my ball milling helps bring down
usable weight. If you've already hit low 1.40's and it settles or applies
too thin (test on bisque) you can raise viscosity and application thickness
epsom salt solution (added very carefully or you'll get a bucket of
pudding.)
Regarding the right weight, I'm sure you know that any glaze with visible
cracks or pinholes when dry is very likely to fall apart in some way in the
firing. I've tried optimism and thinking pure thoughts about a different
outcome but found it generally futile.
Or maybe the answer is to say no to the fake maiolica and  find yourself a
genuine maiolica  - somebody has to keep tin mines busy!

Jeff
Jeff Lawrence
jefflawr at gmail.com
jeffreylawrence.net
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