the worst books for errors seem to be the ones that claim to be the ultimate resource, the "bible", the "complete", etc. one had a simple heading wrong, C was reversed with F for the cone temp charts. just a little mistake.
Pottery Knowledge Quiz Of The Week (Pkqw): Week 1 And Introduction/answers Included
Posted 05 April 2017 - 08:50 AM
Okay folks, here are the answers. I am sorry to say, I am calling foul on the writer of question 3, or the answers for question 3 as someone was not thinking too well. Maybe we'll have to give him a good talking to. At any rate the answers are here, and if you redo 3 you will find that there are two options to correctly answer the question. Duh, my bad.
Week 1 Answers
Egyptian paste is a single fired, high flint earthenware that develops its own glaze from ___________ _________ carried to the surface from evaporation.
a. excess alumina
b. soluble salts
c. added bentonite
d. sodium silicate
Egyptian paste is a single-ﬁred, high-ﬂint earthenware,
which develops its own glaze from soluble salts (soda ash)
carried to the surface through evaporation.
Clay saggars for multiple firings may be made using a clay body that is high in __________ to prevent warping.
Saggars (which are stackable clay boxes that hold ware and
thus are typically used in place of shelves) must be made from
a clay body that can be ﬁred repeatedly while maintaining a
warp-free shape even under a significant ware load. They can be
made from a variety of clay bodies, but the ones containing
significant mullite are especially warp resistant and durable.
There are no federal standards for labeling ware “dishwasher safe”, yet modern day dishwashers pose two threats to ceramic dinnerware.
Physical attack caused by a combination of __________________________results in crazing.
a. vibration and sonic resonance
b. alkaline detergents and water
c. high speed water jets and soak periods
d. high heat and moisture
“What actually constitutes "dishwasher safe”?
Nearly all stoneware and porcelain competently produced
by functional potters is “dishwasher safe,” in the sense that it will
not deteriorate or give off toxic quantities of harmful sub-
stances, but most potters ought to know more about the
subject. While there is no federal standard for labeling ware
“dishwasher safe,” automatic dishwashers pose two threats to
The ﬁrst is a physical attack caused by the combination of
high heat and moisture, which may take its toll on relatively
porous bodies by causing their expansion and contraction. The
result is a crazed glaze surface. Vitreous porcelain or stoneware
is the most resistant to this problem, but if the body is
underﬁred or has significant glaze/body interface stresses, it,
too, may fall prey in the dishwasher to increased susceptibility
to crazing, chipping and shivering.
The second threat is chemical attack by alkaline detergent.
The harder, more completely melted and insoluble the glaze,
the more resistant it will be to dishwasher detergent. Higher ﬁred
glazes tend to be more resistant. Low-ﬁred luster glazes are never
dishwasher safe and eventually are dissolved by low-viscosity,
alkaline detergent. Matt glazes may be quite susceptible to dissolv-
ing, and earthenware matt glazes are the most suspect. Some
earthenware glazes can even become porous after repeated washing,
and any glaze that exhibits this quality should be excluded not only
from the dishwasher, but also from use with food.”
Many of us have been taught that wedging clay removes air bubbles that cause explosions, often dramatic, in the bisque fire. The true culprit for the “blow up” is __________________.
a. poorly wedged clay
b. poor uniformity of clay
c. insufficient drying of ware
d. bone dry ware
Most any time a pot actually blows up in ﬁring, the culprit
is steam produced by water trapped in the wall.. . . .
When pots are completely dry before ﬁring, steam is not a
problem. The kinds of blowouts . . . simply demonstrate the prior location of the water and the weak points the steam finally found to release pressure. . .
This weeks questions were taken from text in Answers to Potters Questions II, Ceramics Monthly.
Posted 05 April 2017 - 10:45 AM
While there are other issues in defining "dishwasher safe", as per your discussion of the answer, if one carefully re-reads the original question, one finds that only option D addresses "crazing".
No reason to call foul on the author of the quiz (you). It is the responsibility of the "student" to carefully answer the questions as asked.
Respectfully submitted by another long time teacher.
Posted 05 April 2017 - 11:07 AM
Yep Fred, complex issue. Alkaline detergents break down the surface, and the heat and moisture cause crazing. If looked at together, the two really will break down any immature glaze. At the same time how hard does glass have to be to survive the dishwasher. I have measuring cups that were made in the 70's that have a fog on them. This fog is not a residue, but an etch into the surface of the glass. At the same time I used to use matt glazes on my decorative pieces that would allow the decoration to show without reflection, too bad I used the same glaze on functional ware for a few years. Complex issue.
Thanks for the waiver, but I am going to be much more careful. I really think this could be a great idea for the community, and want to do it right.
Posted 09 April 2017 - 12:27 PM
No comments or replies about the answers to the questions? Any complaints about format of answers in this manner?
Raising awareness of my knowledge base and yours is my main stimulus for this idea. I hope you find it helpful.
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