[Clayart] dealing with having to make a taller chimney
mwendt at wendtpottery.com
Fri Oct 23 17:18:52 EDT 2020
Loved the story despite the unpleasant outcome.
She made two mistakes:
First, if she thought you were wrong, she should have shown you the "RIGHT"
way to fire the kiln.
When her "RIGHT" way did not work, she should have apologized to you and
made you feel welcome, not resented.
Sad piece of work, that professor.
There is a really handy small book titled
"Pocket Ref" by Thomas Glover
The price sticker is still on mine all these years later ($9.95)
It is data packed.
It lists the atmospheric pressure at various altitudes.
Most people know that 14.7 PSI is the atmospheric pressure at sea level but
the surprise is, air pressure drops off ever faster as you go higher up.
It makes sense since unlike water, air is compressible so the scale is
logarithmic rather than linear.
I am in Lewiston, Idaho (750 ft above sea level 13.44 PSI avg)
Moscow, Idaho where I grew up and went to school (2500+ ft above sea level
Denver, CO (let's say 5500 ft above sea level 7.33 PSI)
Clearly, a novice flatlander would be shocked at how much harder it is to
reach temperature at Denver's altitude when compared to Lewiston's altitude.
----- Original Message -----
From: "Snail Scott" <claywork at flying-snail.com>
To: "Clayart international pottery discussion forum"
<clayart at lists.clayartworld.com>
Sent: Tuesday, October 20, 2020 12:13 PM
Subject: Re: [Clayart] dealing with having to make a taller chimney
On Oct 20, 2020, at 1:01 PM, Mahaffey, Rick <rmahaffey at tacomacc.edu> wrote:
> Back when I was a studio potter we had to raise the chimney to clear a new
> building in the immediate area. I was worried about the added length
> making the firing difficult so I had an extension made with a small hood
> at the bottom and a 6" air gap all the way around. I had the added height
> needed without adding to the length of the chimney…
An updraft hood and stack can really affect draw, even with a good-sized
I was the work-study tech in school, in charge of firing all the
lower-division classes’ work (among other tasks), pretty much autonomously,
for several years. One summer, the school finally responded to the
complaints of the secretaries on the second floor about the kiln fumes,
since the three big Alpines' updraft stacks ended at their level. The old
stacks were taken down, but the new 3-story ones had not been installed by
the start of the term. We got a new professor that fall, and she wanted to
load whichever kilns with whichever work. I explained that due to our high
altitude and a bad rebricking job, the middle kiln didn’t have enough air
intake to hit ^10 when the atmospheric pressure was lower than average, and
with the stacks off we'd be lucky to hit ^7 or 8, and we needed to stick to
lower firings in that kiln until it got rebuilt. Well, that went over like a
lead balloon: I’d better get loading that ^10 firing into the middle kiln,
she said, even if a storm was coming in. Well, I did it, and sat up all day
and night trying to nurse enough heat-work into that sucker to get even
close to the mark. When she came in at 9 am, 18 hours later, we’d plateaued
at ^8 - thermal equilibrium, more or less. She told me I just didn’t know
how kilns worked (the ones I’d tended and fired several times a week for
three years), and that a stack had no effect on an updraft kiln. When I
protested that the effect was real and obvious, she actually called Joe Bova
on the phone. She demanded that he tell me I was wrong, and put it on
speaker for the whole classroom.
Joe Bova said I was right. (If ‘drop the mic’ had been a thing back then,
and i’d had a mic, I’d have done it.) My days there were numbered from then
on, so it was a bit of a pyrrhic victory. Felt good at the time, though.
Updraft hoods matter!
I do understand how tough it must have been for her, coming in to a new job
and having to deal with an opinionated, independent minimum-wage undergrad
running the shop, but my pride had been injured and I was more than a little
sleep-deprived by then. I do regret having started off so poorly with her,
but it was the push I needed to finally leave and set up on my own.
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