Hiro Matsusaki on fri 7 mar 97
Good taste buds and good sense of smell go hand in hand. Sound body and
sound mind -- the familiar stuff -- leads to sound kiln choice. No, I am not
going to cite anecdotes about how a master kiln builder tasted and smelled
clay to see if it was ready and fit for use, etc. That is out of my range.
Recently, we have had exceptionally well put together posts on the
scientific aspects of it (Aging of clay... 21/02/97 and 26/02/97 by
kevin_hulmes@uk.ibm.com). I liked them very much. I wonder if the aging has
helped me as a person to be kneaded into an artistic stature. But, I shall
eagerly await for any sequels from other clayarters to divulge the practical
secrets (experiences) for mixing and aging of clay that they have uncovered.
Today's clay may be too refined and too antisceptic for our taste. Still,
we want the best formula (least work involved) to get the most profitable
results (the chepest way to get them), don't we? Sharing is not only a good
idea but also a good public hygene for clayarters. No more stupid smells!
The most thorough analysis and problem shooting on gas reduction I have
encountered so far is a recent post: High Alt. Gas Kiln Problem 22/02/97 from
orion@telcomplus.com (Ellen Baker). If you are interested in reduction, and
technical treasure chests, this is a must. You will also find similar posts
from the same source very informataive, enjoyable and pleasing to read(28, 25
& 14 /02). I think the credibility of the source is impeccable. Back to the
smell now. ... Readily available heat energy sources in North America for
gas kiln are natural gas and propane. Natural gas does smell. Propane
stinks. This is for a good reason. I feel that propane is far more
dangerous than natural gas for use in kilns, when leakage should occur.
LPG (Liquified Petroleum Gas) is the main source of heat in urban centers in
Japan, and explosions do take place in congested cities over there --
localized damages -- from time to time. Most of them are due to human
factors. Much higher level of budget deficit dedicated to the public
education in high school English supervised by famed Oxford graduates (at
one time, hundreds of them year after year in order to cut down the exchange
surplus conundrum) coulc not cope with the crowded rabbit hutch situation
over there. Small explosions that singe eyebrows used to be common
happenstance in the confined space where there are abundant heaters for those
hot bathtubs, a civilized pastime, a wonderful ritual to keep clean and
comfortable against humidity and non-centralized heating. I personally
experienced one, curtesy of my spouse who did not know the primitive firing
method and was always in great haste. The human relations skill was
irrelevant (I felt it was time to learn), since I had overheard some talking
or shouting before the bang and the lost eyebrows. Needless to say, when
ignited under "ideal" conditions (such as might exist in an amateur pottery
studio), the gas explodes. The oxygen must be present in proper amount for
the gas to exploede. Only about one-fifth of air is oxygen, the rest
four-fifth mostly nitrogen, an inert gas. In small amount, oxygen gives life
and takes it away. In abundant air, wood oxidizes and become wood fire.
Same goes for gas. Gas fire. No different in terms of oxidization, but the
flames generated are quite different. Hence they act on clay pots in the
kiln differently (let's say we shall disregard such things for now).
Wood burns (oxidizes or chemically reacts with oxygen in air) slowly, and
needs to be split into smaller pieces for quick, rapid heat. This gives more
surface area to be exposed to air for the same amount of combustible mass.
Gas is supplied under pressure and no serious or hard work (like head
splitting) are called for. Just a flick of the wrist to get the quantity we
need. Turn the valve and that's it. It's so easy to do that propane bottles
have threads the opposite way to keep children away from turning the
turnable. I still do not learn this after years of turning the pots, by the
way. Faced with those, I often struggle to turn the knob the regular way.
No deal. I forget what I did the last time, etc., you know, to turn me on.
In clay. But that's another story. Well, gas is much easier to adjust for
volume demanded than wood. It can be slow burning as in pilot flame in the
furnace (or candling of gas kiln) to the very fast concentrated heat to
incinerate some toxic chemicals (no wonder crematoriums use it, ... sorry
for unwanted innuendo...we eat food soaked in chemicals and are surrounded by
all sorts of pollutants, additives and preservatives...these days). Since
it's under pressure for transport, if not properly controlled, gas can leak
and cause explosions. Despite the best maintenance (qualified and
professional care) and proper precautions (periodic rounds), natural gas
wells (to pump it out from underground reservoirs) do blow up occasionally,
providing the photo opportunities and sensational local news (ignored
elsewhere).
If released into air inadvertently in a kiln shed, the gas cannot be seen by
naked eye. Propane hugs the ground, since it is heavier than air, while
natural gas tends to go upstairs toward the ceiling because it's lighter than
air. But their behavior is unpredictable. Both can explode (a rapid, sudden
chemical reaction with oxygen). So, anyone with poor sense of smell should
stay away from the propane or barbecue picnics. A common sense, isn't it?
Regardless of the sense of smell, or the gas used, potters should build an
airy kiln room. Any unburnt propane gas should flow away if proper paths are
provided. Since leaked natural gas hover around, proper vents should be
built into a roofed building or shed.
This precaution is easier said than done. People forget. The door shut
tight, the vent switch forgotten, and sometimes our sense of smell (danger)
dulled due to familiarity. Others like the warmth and privacy of the kiln
room that closed doors can boost. I have seen a lot. Believe me. So, it is
important to double check the built-in safety features. It is possible to
build a kiln to use both propane and natural gas interchangeably, depending
on need (Why not? This is my personal preference). Today's burners are made
so that no accidents should occur. Idiot proof. But we are not idiots. So
we do all sorts of things which idiots do not do. Too bad. If we burn gas
in a room where the door is tightly shut, or too strong reduction is
attempted, and the vent malfunctions, not enough air (oxygen) would be mixed
with gas. Unexpected accumulation of unburnt gas can cause an explosion.
Let us say, like the movie backdraft, where outside air rich in oxygen
enters a room.
I have seen experienced, educated potters who did not understand the basic
difference between these two types of gas, let alone the ramifications
(dangers) of leaked gas. These are actually very elementary stuff, probably
more so than the use of electricity. Leaked gas does not always explode even
though the person may be so stupid as to light a match with a gas mask on.
But leaked electricity at 220 volts is lethal to the uninsulated person
standing fully clothed in a pool of water, or lying naked in a bath tub.
Heavier clothing has nothing to do with it, although it may smell. Heavier
air, on the other hand, affect the behavior of gas. And the composition of
gas or its heat value or weight also varies. Air is significantly heavier
(denser) at the sea level. The weight of the air above compresses it.
Colder air is heavier than warmer air. It takes less fuel for jet planes to
take off if the air is colder and the airport is located closer to the sea
level. Under such conditions, the air gives more lift. Large, traditional
gas kilns are noted for their sensitivity to weather condtiions. The leaked
gas may behave differently depending on the surroundings and the conditions
of air. But I have never personally checked this out in detail by
deliberately exploding gas. So I don't know. And I don't want to be a human
guinea pig.
Human sense of smell is not only the key to the potential dangers of gas
explosion but also the defense against the rats hanging around the gas kiln.
Before the government downsized the bureaucracy, one of the top gas
inspectors (supervisor) told me that he did inspect one kiln and he was the
most qualified of the inspectors for the natural gas safety for potters in my
area. He was pround. What he implied was that other inspectors did not
understand the pottery making business (I say-- this business of how idiotic
potters could be). The point here is that the public safety was at issue,
and elaborate mechanisms existed to ensure it. My horse sense dictated an
opposite danger (of chewed up wallets or holes in my pockets from rats
bites), but I held my tongue. A small hobby gas kiln cannot be any more
dangerous than the furnace in the house, I felt, since it is used only
occasionally and located not in a well insulated house, but in an open
separate building like an empty garage. Interestingly and in contrast, the
propane is subject to far less paperwork. No maintenance inspections till a
few years ago. Where I live. Honest. Things like 100 lbs bottles from
1950s were littering old farm houses around us.
Years ago, no one was allowed to hook up refrigerators. Only qualified
individuals were allowed to do the job. Today, we simply plug a fridge into
a wall outlet. The design of the equipment, meanwhile, changed also. Just
an ordinary plug. Similar things happened to electric dryers, although the
plug is far thicker and heavier. Today, the basic house wiring include the
dryer and oven connections. Just plug them in. Still, anything that takes
up more power like a large electric kiln or even a commercial grade
convection oven need a separate wiring which demands an electrician's
service. We have not progressed much in these affairs, since, if my memory
serves me right, only thirty years ago it was legal not to hire a woman
because the job was not for woman. The same with electricity or gas. It was
perfectly legal to keep the person with an electric engineering degree away
from the house wiring if he did not have the ticket. And to get the ticket
one had to go through a long apprenticeship to provide cheap labour to the
master electrician. I hope a master potter may have a similar privilege one
day! What? Did you say it already exsits in North America?!?! I don't think
so.
For most of us the two live wire business is a big mystery at 220V. In most
European countries 220 volts AC is the norm for average household, which is
enough to fry any North American appliances over there. You cannot use even
a small iron or shaver without a converter. Lucky for us. We are noted for
the penchace to experiment, i.e., we would not mind getting fried by trying
new ventures ourselves. Over here, the 220 volts business demands a lot in
terms of wallet and mental fortitude. At last count some time ago I noticed
several plugs for proper hookup of electric kilns at that voltage for
different amperages and locales. A wonderful setup to confuse everybody.
The situation with gas is worse. (This is my personal view. I lived in
many, many places, but with a relative isolation from the gas,) Gas fridge
and dryers for domestic use must meet the inspections or somewhat similar
requirements which only gas fitters are allowed to work on, theoretically.
The basic electrical codes are more or less uniform no matter where you go
in North America. But the gas use seems to be subject to far more local
control anomalies. With newer materials on the market for hooking things up,
the situation is rather confused, although the physical jobs of connecting
gas are getting much easier. Documentation on use of electricity and gas
abound today, so what used to be trade secrets are no more. Some subject
matters are still difficult to find, the Internet excepted, I guess. For
instance, I have noted only one good book on the home or farm sceptic water
system.
I used to admire electricians, welders, pipe fitters and the ilk. They all
seemed wealthy, and very well paid. Now I live close to one of the blue
collar capitals in an area endowed with oil and natural gas. I don't know
how this alter ego bias affected me, but till few years ago, one of my
favorite pasttime was to visit a local bar and rub elbows with the local
trade types over mugs of beer. I learned a lot. Only a few are well
educated (in a formal sense), but the educated ones (like me) were quite
lazy, since they were too smart to be wasting time servicing customers or
going after more money. Others with limited education actually knew far less
on electricity or gas than what is stated in a thin book. Besides, all of
them smoked and quite sloppy on the job, scattering cigarette butts and other
ends or pieces all over the floor, things like that. I know. It was me who
always swept and cleaned up the floor. They were so clumsy that I bet they
can never throw clay. At any speed. What I can learn from reading in a few
days, those guys (no gender slant here) make a living out of it, since they
belong to a guild or a union and the law was behind that authority. The
danger to their lives were overstated, since they smoked while working. You
know the macho thing? They seldom deal with the wicked criminals with whom
the police must contend. The danger is definitely overstated, but their
techniques were a closely guarded secret. Electricity behaves, more than
gas, it does exactly what you want it to do, as long as you know what you
want. It keeps the line. Gas is a runaway, goes wherever it can as it
chooses. But it seldom harms you, since the stray gas is normally of small
quantity and shuns familiar scene for fear to get trapped and sent home.
Well, danger of gas is overstated, in my view, much more so than electricity.
It leads to convincing statements by the party in the know or in the
position of authority. My observations tell me. For one thing, the gas
people have to know relatively far less than electricians to deal with the
home gas use. For another, they are often employed by local suppliers to do
specialized, repetitive tasks like pipe or valve fitting and meter checks.
For this reason, a seemingly qualified person often do some "stupid" things
which even I could detect. I guess the better ones are at oil and gas fields
and do not frequent local bars on workman's compensation or injury claim
checks.
You see, gas pressure is normally stepped down to be in safe range, and any
leakage from pipe joints and the like can be tested with soapy water or
detergent which would bubble up, besides the nose test of smell. Try blowing
a few bubbles first, to see if they work. Do not use on freezingly cold
pipes. Electricity has a multi-stage safety switches that automatically shut
it downstream of the system if any leakage occurs. Good insulation helps,
and excellent gauges are available at any hardware stores to tell if the wire
is live or not. In contrast, not much equipments for gas are commonly
available to give help. We are not supposed to touch the domestic gas stuff,
but can find the propane gadgets for picnics or RVs at sporting goods store
in abundance. The rest are held jealously by local supply monopolies, and
not easy to use even if you can find (buy) it. This rule does not apply,
however, if you have the money to burn or the public budgets as the last
resort.
As far as the smell of gas goes, we have to watch out, do research on our own
the best we could, and make sure to which sources we should be connecting.
Local conditions vary a great deal. And the money cannot assure the quality
you buy. In industrial applications, pipe fitters cut pipes that fit, and
welders weld what have been already cut. Neither would be movers of pipes.
Clear division of labour has been established.
Electricians come in all variations as well. Several years ago, I wanted to
use two tabletop ovens, and hired one who was neither too cheap nor too
expensive from the look of his phone line in the yellow page. He came with
an apprentice so that he could justify his middle of the road rates. He had
to change the distribution panel, the main switch for the power in the house,
to accommodate the change. After the update, the stoves were connected. One
worked. The other did not. Since I saw this assistant flipping the rotary
switches of the stove vigorously with the power on, I stopped him, mentioning
abuse. No, the electrician said the stove was broke. You said you bought it
second-hand, didn't you? Nothing can be done. That was that. He left with
the stove firmly connected (direct to the panel). Although I could not find
anything physically wrong with the stove. It had five or six wires, all
different colors, and looked confusing, so I stopped testing it. Some two
months later, I hired an electrician buddy from the local bar to make two
downloads for electric kilns (at 75 amp each). When we were at liquid
breakfast, he looked at the stove connecvtions and in three seconds he found
that the stove was connected wrong, and within a minute the stove was working
normally. I was asked, but did not give away, the name of the culprit
electrician. They belonged to the same family, and I did not want any
fallouts.
I still remember this incident. When I repeated the request that the stove
should be checked before writing it off, the guilty electrician had the gall
to refuse it saying that the stove was broke. I bought a defective one. A
simple flat statement. How can I argue? No way. The chances were the stove
was defective, and not the electrician, right?
Does this incident perchance reminds you of someone you know? Watch out for
any flat, authoritarian statements from the person who does the work, any
work, for you. Be critical even on things you do not know or understand.
Ask "stupid" questions. That should negate their veil, cloak and daggar.
If they feign indignation and impatience, something must be wrong.
HM
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