Ben Friesen on fri 21 jan 05
Can crazing ever effect the strength of a vessel? I've had handles break =
off a few mugs lately that have all been glazed in the same glaze... =
this particular glaze crazes quite badly, the handles are thin =
(extruded) and I've begun wondering if perhaps there's some relation =
between the two. As I've pursued the reasons I've found that the mugs =
have perhaps been bumped in the dishwasher, etc but it's been very =
slight. Now I'm scared to sell them..... or anything with that glaze... =
and I have some of the same ware sitting in shops, oh no.......=20
Ben Friesen
Stonepath Pottery
Abbotsford, BC, Canada
Rod Wuetherick on sat 22 jan 05
Ben,
Crazing can dramatically affect ware strength as Ron Roy, etc. will tell
you. But that being said if you have handles coming off your pots I would
not blame the glaze. In other words you shouldn't be able to pull a handle
off a mug even if there were not a drop of glaze on the vessel.
I would investigate your application of handles. What state is the mug in
and what state is the handle in, etc,
I truly would believe that is would be folly in this case to blame crazing
as your problem.
I'd also work on that crazing problem. Pick up the Currie books, etc.
Cheers and good luck,
Rod
Can crazing ever effect the strength of a vessel? I've had handles break off
a few mugs lately that have all been glazed in the same glaze... this
particular glaze crazes quite badly, the handles are thin (extruded) and
I've begun wondering if perhaps there's some relation between the two. As
I've pursued the reasons I've found that the mugs have perhaps been bumped
in the dishwasher, etc but it's been very slight. Now I'm scared to sell
them..... or anything with that glaze... and I have some of the same ware
sitting in shops, oh no.......
Snail Scott on sat 22 jan 05
At 09:06 PM 1/21/2005 -0800, you wrote:
>Can crazing ever effect the strength of a vessel? I've had handles break
off a few mugs lately that have all been glazed in the same glaze... this
particular glaze crazes quite badly...
YES! Glaze bonds to the clay, and when it crazes
(after it's cooled and becomes a rigid material)
the cracks extend slightly into the clay body as
well.
-Snail
Steve Slatin on sat 22 jan 05
Ben --
Let me suggest a possibility here -- you say the glaze
crazes badly. Any glaze will, if the 'fit' between
clay and glaze is bad enough. If the
expansion of the clay is too high for the body, you
get crazing. (You also can get it from overly rapid
cooling, presumably something you've already taken
care of.)
So can a poorly fitting glaze cause a handle to come
off? I'd look at how your handles attach. If they
come straight, 90 degree angle out of the cup, I'd
suspect something else. If they come out at an angle,
and there's a spot for the glaze to 'pool' on one side
and not on the other, I'd be suspicious of the
combination of shape and glaze fit as a possible
source of the defect.
All speculative, take it for what it's worth ...
-- Steve Slatin
--- Ben Friesen wrote:
> Can crazing ever effect the strength of a vessel?
> I've had handles break off a few mugs lately that
> have all been glazed in the same glaze... this
> particular glaze crazes quite badly,
=====
Steve Slatin -- No one, having once come to the attention of the authorities, is ever thereafter truly forgotten.
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Ron Roy on sun 23 jan 05
Hello again Ben,
Crazing does make pottery weaker but I have never heard of it resulting in
handles breaking spontaneously. If your handles are really thin I suppose
it could happen - I would suggest you make some thicker handles and see if
the problem is still there.
RR
>Can crazing ever effect the strength of a vessel? I've had handles break
>off a few mugs lately that have all been glazed in the same glaze... this
>particular glaze crazes quite badly, the handles are thin (extruded) and
>I've begun wondering if perhaps there's some relation between the two. As
>I've pursued the reasons I've found that the mugs have perhaps been bumped
>in the dishwasher, etc but it's been very slight. Now I'm scared to sell
>them..... or anything with that glaze... and I have some of the same ware
>sitting in shops, oh no.......
>
>
>Ben Friesen
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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