search  current discussion  categories  kilns & firing - coatings 

out of the tunnel and into itc! [long]

updated sat 26 jun 99

 

gwalker on fri 25 jun 99

------------------
G'day Claymates=21

I'm finally climbing out of what has been a very dark tunnel. After
coping with the initial devastation caused by the massive kiln
explosion, I am afraid I settled into a period of extreme flatness =85 a
feeling that is only now leaving me. Five weeks being unable to do any
reduction firings was not only a financial disaster, but an emotional
one as well. Compared to the suffering of some of our claymates here
though, this has been chicken feed. As I have said before, =22I can count
my lucky stars=22.

So=21 To report in on the re-furbishment of the replacement kiln. A few
years ago, I bought from a pottery which was closing down, a 40 cub.
ft., front loading gas kiln. It was green in colour, and for this, and
other reasons, it was christened, =22The Green Frog=22. Although not soundly
lined with fibre, it could be fired to cone 10 reduction in about 6
hours (even using only 4 of its 6 burners), allowing us to produce a
kiln load per day if necessary. Rather than using =5Bits now destroyed=5D
large counterpart (200 cubes), we could push through smaller quantities
almost at will.

The poor quality of the construction and lining, however, took its toll
over time resulting in this poor little Green Frog eventually being put
out to pasture, so to speak. (As opposed to stud work=21 LOL=21)

Being unable (nor inclined) just now to afford a replacement for the
=22Big Top=22 kiln (subsequent to the =22big bang=22), I decided to re-line =
the
frame of little Green Frog, and put him back on line. Thanks to the hard
work and generosity of three dedicated friends (thank you, Frank, Ed and
Mark), the little monster was back in action about two weeks ago. The
roof, rear and door were stack-bonded whilst both sides were wallpapered
with 5=22 of hot face fibre. At the same time, we eliminated the two
central burners on either side, deeming them superfluous and unnecessary
for power, efficiency or evenness.

The aluminium and steel frame was in reasonable order (although the
aluminium around the door had melted in several spots, necessitating
replacement and further bracing), and a wheel was added to the hinged
door to counter sagging due to the extra weight of fibre and additional
metal.

The final step was to coat the fibre with ITC 100. A search of the web
located a local distributor in Brisbane to my delight and dismay (only
55 miles up the road), and a 'phone call had a rep. on my doorstep next
morning. They had ONE GALLON (actually, two half-gallon pails) in stock
which fortunately was about the quantity I needed. The pails arrived
next day with verbal instructions, necessitating another search of the
web and the archives. (Thank you, troops=21)

Spraying the stuff became the next nightmare. I don't know (and can't
find out from the local supplier) whether it is normal for the ITC, when
mixed 50:50 with water, to settle almost instantaneously to the bottom
of the pail. Maybe it was because it was old=3B had spent too long in its
travels=3B had =22gone off=22 (certainly smelt a little like an old bait =
tin=21)
=85 not sure =85 but the grey sandy mixture (I suspect this is zircon sand)
needed constant agitation to keep it in an employable state.
Frustrating=21

Spraying proved equally challenging. None of the spray guns we use
regularly could cope with spraying this =22stuff=22 so, after long and
fruitless searches, I finally managed to hire a low pressure gun which I
was assured would do the job. NOT=21 2 or 3 seconds of spraying was about
all we could achieve before dismantling and cleaning of the gun became
essential. I had been assured that this gun was designed to spray putty,
so should work just fine. What do they know?

Fortunately, the young chap who had =22volunteered=22 to do the spraying for
me was a professional spray painter who, anticipating a problem, had
thrown another type of (spray) gun into his vehicle. What a godsend=21
This gun was of the type used to spray sound-deadening or stone-guard
material under mudguards and sub-frames of cars. It worked brilliantly=21
More like =22splattering=22 than =22spraying=22. An added advantage was the =
fact
that the canister containing the ITC did not have to be attached to the
gun proper, allowing this canister to be constantly and vigorously
agitated, negating the powerful tendency for the stuff to settle out. We
had only wasted a little more than an hour with the other gun,
fortunately.

The finished surface, I have to say, is brilliant. Although extremely
thin, it is very hard. It can be cracked and will flake away if
accidentally struck, but with care should last a long, long time. I have
also noticed that there appears to be far less shrinkage of the fibre
with this coating, although Bill is only about half way through the
ninth firing. I DO, however, hold out great hopes for this =22born again=22
Green Frog.

As to efficiency: I have no data on gas consumption as yet, but suspect
that will be down noticeably due in part to the additional fibre (at
least an extra inch in most places). This extra insulation in
conjunction with a re-arrangement of the shelving to provide 30=25
additional packing space, has created one unforeseen problem, however.
The extra time taken to pack, and for it to cool, means we can no longer
fire this little darling every day. Pity, that=21

One last thing =85 I am not sure what role the ITC coating is playing in
this, or, indeed, if it is playing any role at all, but the outer case
is noticeably cooler. Of course there is the additional fibre and this
could be the sole reason, but I suspect not, listening to the rep. from
Pinches Alloys. He expected that the surface temperature of the metal
casing would drop by anything from 40 to 60 degrees Celsius due to the
ITC coating.

Any of my Aussie claybugs out there who want the contact details for
Pinches Alloys in Brisbane, Sydney or Melbourne, please e-mail me off
list.

If you have read this far, thank you for your patience. I do tend to be
just a tad verbose, I know. Just glad to be back on deck again =85 I have
been lurking when I could, though=21 =3B-)

Clay hugs,

Geoff.