Cork: Its Origin and Industrial UsesStecher, Gilbert Erwin
Science
Cork: Its Origin and Industrial Uses
Stecher, Gilbert Erwin
Cork
The corkwood bale as received, measures as a general rule 2′ × 2′7″ × 4′
and is securely strapped with iron bands about one inch in width and a
thickness of 1/16″ to 1/32″, and the weight depending upon the quality
of corkwood ranging from 150 pounds to 200 pounds per bale.
SORTING
The first operation, that is, the first thing done with the corkwood, is
the sorting. This is becoming more important as the uses of cork
increase, as various grades can be used for so many particular things
now, without the necessity of being called a by-product; but the
principal divisions are: superfine, fine, common and coarse.
These of course are now extended to many classes, and is resulting in
careful scrutiny of the shipments and stock, the sorter becoming an
expert, and an increasing factor in the business. His knowledge not only
including the grades of corkwood, but the uses to which the various
grades may be put so that waste is avoided and the full value gotten out
of all.
CORK STOPPER MAKING
After the sorting, the slabs are placed in steam boxes and subjected to
a steam bath, which it is claimed softens the material and also prepares
it for the scraper, who cleans and removes the dirt and callous or
“raspa” accumulated in its mountain home. This scraping is done either
by hand or machine, the handwork being done with a short handle, curved
bladed knife called a “doladera,” raspador or raspeta: a workman being
able to scrape from two to three metric quintals of cork in a day, or
ten hours. The scraper machine being a vertical steel shaft carrying
several knives placed at a very slight helix and making about 1400
revolutions per minute and will scrape from ten to twelve metric
quintals[35] per day or ten hours. Cutting the slabs into strips or
fillets (tiras ó’rebanadas) is the next step. These strips, the width of
which is equal to the length of the cork to be cut, as the cutting is
done across and not with the grain, were formerly cut by hand with a
knife having a flat surface and curved edge called “cuchilla de
rebanar,” but now replaced by the circular knife, which operates the
same as a rip-saw. From here the strips go to the stopper-makers’
punches or blocking machines. This machine has a rotating tubular die
with sharpened edges of the diameter of the cork to be cut, made to
revolve about two thousand revolutions per minute, the operator having a
foot lever attachment which permits him to thrust the die through the
strips of cork as he holds it against a resisting piece parallel with
the operating plane of the die. Thus, he can punch out many thousands of
corks a day, the noise of the punches being a very characteristic sound
in all such establishments. The operator, of course, must use care to
avoid defective spots in the bark, and also to cut the corks out as
closely together as possible so as to reduce waste to a minimum. For it
is here that the cork manufacturer seems to lay his particular lament.
Public-domain text, read in full here on John Shaqi.
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