This was posted on the 16mm NGM forum as a salutary tale about the risks (and pleasures?) of using expanding foam without first reading the label! Apologies if you've seen it before ..............
Rik
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FUN WITH FOAM....................
A friend of mine once built a canoe. He spent a long time on it and
it was a work of art.
Almost the final phase was to fill both ends with polyurethane
expanding foam.
He duly ordered the bits from Mr Glasplies (an excellent purveyor of
all things fibreglass) and it arrived in two packs covered with
appropriately dire warnings about expansion ratios and some very good
notes on how to use it.
Unfortunately he had a degree, worse still two of them. One was in
Chemistry, so the instructions got thrown away and the other in
something mathematical because in a few minutes he was merrily
calculating the volume of his craft to many decimal places and the
guidelines got binned as well.
He propped the canoe up on one end, got a huge tin, carefully measured
the calculated amounts of glop, mixed them and quickly poured the
mixture in the end of the canoe (The two pack expands very rapidly).
I arrived as he was completing this and I looked in to see the end
chamber over half full of something Cawdor's Witches would have been
proud of. Two thing occurred to me: one was the label which said in
big letters: "Caution - expansion ration 50:1" (or something similar)
and the other that the now empty tins said "approximately enough for
20 small craft"
Any comment was drowned out by a sea of yellow brown foam suddenly
pouring out of the middle of the canoe and the end of the canoe
bursting open. My friend screamed and leapt at his pride and joy
which was knocked to the ground as he started trying to bale handfuls
of this stuff out with his hands.
Knocking the craft over allowed the still liquid and not yet fully
expanded foam to flow to the other end of the canoe where it expanded
and shattered that end as well.
A few seconds later and we had a canoe with two exploded ends, a
mountain of solid foam about 4ft high growing out of the middle, and a
chemist firmly embedded up to his armpits in it.
At this stage he discovered the reaction was exothermic and his hands
and arms were getting very hot indeed. Running about in small circles
in a confined space while glued to the remains of a fairly large canoe
proved ineffective so he resorted to screaming a bit instead.
Fortunately a Kukri was to hand so I attacked the foam around his
hands with some enthusiasm. The process was hindered by the noise he
was making and the fact he was trying to escape while still attached
to the canoe.
Eventually I managed to hack out a lump of foam still including most
of his arms and hands. Unfortunately my tears of laughter were not
helping as they accelerated the foam setting.
Seeking medical help was obviously out of the question, the
embarrassment of having to explain his occupation (Chief Research
Chemist at a major petrochemical organisation) would simply never have
been lived down.
Several hours and much acrimony later we had removed sufficient foam
(and much hair) to allow him to move again. However he still looked
something like a failed audition for Quasimodo with red burns on his
arms and expanded blobs of foam sticking everywhere. My comment that
the scalding simply made the hairs the foam was sticking to come out
easier was not met with the enthusiasm I felt it deserved.
I forgot to add that in retrospect rather unwisely he had set out to
do this deed in the hallway of his house (the only place he later
explained with sufficient headroom for the canoe - achieved by poking
it up the stairwell).
Having extricated him we now were faced with the problem of a canoe
construction kit embedded in a still gurgling block of foam which was
now irrevocably bonded to the hall and stairs carpet as well as
several banister rails and quite a lot of wallpaper.
At this point his wife and her mother came back from shopping......
Oh yes - and he had been wearing the pullover Mum in law had knitted
him for his birthday the week before.
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