search  current discussion  categories  glazes - chemistry 

thermal shocking mugs!!

updated mon 30 jun 97


Wint Harris on sun 22 jun 97

Marshall and others,
I have thought the freezing of and boiling water test of mugs a bit sereve =
it's suggestion here on the list=21 It seems like a severe =22acid test=22 =
at best.
Now, Marshall, I haven't had any mugs returned from cracking. Maybe they =
crack=3B maybe the customers don't tell me if they DO crack. I sell a lot =
of red
earthenware mugs. I fire lower than you do and I fire oxidation VS your
reduction. I also use commercially mixed clay (e-mail me privately about my
supplier) Vs your own formula. The SCIENTIFIC variables for this are =
vast=21 My
solution...keep doing your mugs. Replace what you have to and disregard the
Expecting the heat...

Talbott on mon 23 jun 97

We sell several hundred mugs during the summer and have had only 5 or 6
returned... I can't imagine what these guys to cause these things to crack
but I suspect it is something beyond normal use.... I feel that it is a
good idea to preheat any piece of pottery before you pour boiling water
into it although we don't do it ourselves and have never had a mug to
crack.. One time a customer (a medical doctor) said he had a mug to break
and his wife was standing there beside him and said.. "well you dropped it
on the floor what did you expect..." I said bring the mug to me and I will
replace it.. of course he never did... There will always be customers that
try to take advantage of the retailers...

I do intend to give out a pamplet or letter to every customer stating
proper care of pottery:
>Preheat teapots with warm water,
>Do not sit pottery on a stove top,
>Sudden dramatic temperature changes are not recommended as this can cause
>thermal shock and chipping...

The same pamplet will also explain return policys, warranties.. (case by
case basis) ...etc...


Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
WBS Live Chat Room, Sat Nites 10 PM EDT, Private Room: Clayarters