clifton wood on sun 17 apr 05
this isn't a smart ass posting.
really.
but with all the discussion about glazes crazing....how do you know if a
glaze that looks good to the naked eye isn't crazing?
i understand that some crazing can be easily seen.
and some you need to stand in really good light with really clean glasses.
some you need a hand lens to see.
and some you need to soak in some staining liquid to see the crazing
so.... for those who object to crazing... how are we detecting crazing
to begin with?
and how much is too much?
i don't know a lot about ceramics...
but i got an elementary introduction to crazing.
my studio mate & i found a gorgeous white matte glaze. stunning.
so we decided to do some color line blends with it.
and the line blends had EXTENSIVE crazing.
i looked at the white matte glaze... couldn't see the crazing. used a
magnifying lens. couldn't see it.
finally i brewed a strong cup of tea, left a test tile in it for a
couple days... then i could see the crazing.
makes me wonder how many of the other glazes i use would reveal crazing
if i soaked them in some staining liquid.
clifton, norwich & sabra - www.catclay.com
Cindy in SD on mon 18 apr 05
Dear Clifton,
All the methods you mention will help to detect crazing. To add a few
more . . . dust some talc or other fine powder on your glazed surface
(something flat, such as a plate)--just a tiny pinch. Surface and powder
must be very dry. Waft a little breeze across the surface, either by
blowing or fanning with your hand--whatever works best for you. Look at
the surface from an acute angle, in good light. The powder will often
make faint lines in the craze marks. I found this out because some of my
plates had become dusty and I happened to see the crazing. That was the
event that motivated me to pursue my own, homemade glazes so that I
could have some hope of making them fit.
Another thing that will clue you in is the pinging (if you have good
high-range hearing). You will hear faint pinging, sometimes for weeks or
months after you remove your pots from the glaze firing. Usually, it
will start right away, but this isn't always the case.
Also, little hand magnifiers of the type used by collectors and jewelers
can give better magnification than average hand lenses. They're really
great if you get the kind with lights in.
It's a good idea to look hard at any new glazes you mix or purchase for
utilitarian work. You are right--crazing, particularly in glazes that
match the color of your clay body, can be difficult to see.
Best wishes,
Cindy in SD
Ron Roy on wed 20 apr 05
Hi Clifton,
Mashed potatoes is the smart ass answer.
I first noticed crazing on my Tenmoku glaze when the steam from the mashed
potaoes revealed it. So steaming is one way - the water will evaporate fron
the cracks last.
If a glaze is crazed - and you ping the pot with your finger it will not
ring for instance.
A decent magnifying glass ( 10x) will usually show it up.
How much is too much - now there is a loaded question - you can be fairly
certain that crazing will get worse over time - most of it will wind up
finely crazed.
RR
>this isn't a smart ass posting.
>
>really.
>
>but with all the discussion about glazes crazing....how do you know if a
>glaze that looks good to the naked eye isn't crazing?
>
>i understand that some crazing can be easily seen.
>
>and some you need to stand in really good light with really clean glasses.
>
>some you need a hand lens to see.
>
>and some you need to soak in some staining liquid to see the crazing
>
>so.... for those who object to crazing... how are we detecting crazing
>to begin with?
>
>and how much is too much?
>
>i don't know a lot about ceramics...
>
>but i got an elementary introduction to crazing.
>
>my studio mate & i found a gorgeous white matte glaze. stunning.
>
>so we decided to do some color line blends with it.
>
>and the line blends had EXTENSIVE crazing.
>
>i looked at the white matte glaze... couldn't see the crazing. used a
>magnifying lens. couldn't see it.
>
>finally i brewed a strong cup of tea, left a test tile in it for a
>couple days... then i could see the crazing.
>
>makes me wonder how many of the other glazes i use would reveal crazing
>if i soaked them in some staining liquid.
>clifton, norwich & sabra - www.catclay.com
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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