Measuring
Hardness
in Rubber Surfaces the P & J way.
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Maybe it is true that The Pusey & Jones
Company introduced cast-iron press-rolls in paper-machines, and
maybe not. History has it that cast-iron press-rolls were introduced
some time around 1873. What is true, is that Pusey & Jones
pioneered rubber-covering such rolls. As the story goes, the original
idea came from a machine-tender at a paper mill in New-England.
 As
a consequence of the rubber-covering came the necessity of knowing
the hardness of the rubber surface. The first thing to do was
to establish a standard, and next - or more or less at the same
time - to develop some measuring device, by which the hardness
could be measured - according to the established standard. The
Pusey & Jones Company developed an instrument called the Plastometer.
The devices came with swivel feet so that it could be used on
rolls with a diameter as small as twelve inches without taking
rolls out of the paper-machine. The idea of the Plastometer was
to measure the depth of depression made by a steel-ball, 1/8"
diameter under a constant load of one kilo at a temperature of
seventy degrees Fahrenheit. The reading was to be taken after
sixty seconds, and was recorded on the Plastometer dial in hundredths
of a millimeter. Given this, the measurements were never spoken
of as hundredths of a millimeter, but in degrees Pusey & Jones.
Today, the Pusey & Jones-measurements has
become somewhat outdated, and most people will probably tell you
that the Shore-standard is the only way to go. But the fact remains
that the Pusey & Jones-standard is far more accurate than
Shore - perhaps too accurate. What Shore looses in accuracy it
gains in speed. The Plastometer is big and heavy. And it is slow
and somewhat cumbersome to use, while the Shore-instrument is
small simple and fast - perhaps too fast.
Me - I'll stick with the Pusey & Jones'
Plastometer anytime. I've got one on my book-shelf. Here are two photos of the
Plastometer that sit on my shelf.
Click either image for a larger
view.
This article contributed by Oyvind Haugen. Click here
to
read his bio.
Update March 25, 2004
P&J Plastometer serial number 485.
Finishingnet does not have a lot of information about this
Plastometer or it's use.
We received the following e-mail from Joe Czop 3
photos attached. We are pleased that Joe offered to share the information and
photos with our visitors. If there is
anyone out there can contribute more information about this particularP&J
Plastometer or the knowledge base of P&J Plastometer in general we welcome
your contribution. Pleas contact Luigi at: luigi@paperindustrywebt.com
or Oyvind Haugen at:gringo2@frisurf.no.
Hi ! I am an engineer at Schweitzer-Mauduit Int'l Inc in Lee, Ma. In the good
ol' days this was a Smith Paper Co. Mill. I was surfing on the web and came
across your website on P & J, I found it very interesting !
Attached you will find photos of a Pusey & Jones Plastometer (s/n 485)
that I rescued from the trash can. I don't know how old it is, but it looks a
bit older than the ones on the website that are from the 1950's. For all I know,
it was left over from the Smith Paper Co days. Enjoy !
Note: Click any of
the three images to see an enlarged image.
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