CHAPTER XII
FURTHER APPLICATIONS OF THE VTSCOMETRIC
METHOD
There are many further applications of the viscometric
methods which are destined to become of considerable importance
as soon as the theory of viscous and plastic flow is thoroughly
understood. In many cases however, our knowledge at present
is very restricted, or it is the closely guarded property of some
industry. Generally speaking however, progress has been held
back because the viscosity data at hand could not be interpreted
and because the distinction between viscous and plastic flow was
not recognized. An illuminating example of this has been
described by Mr. Gardner and Mr. Ingalls.1 The American ,
Society for Testing Materials attempted to compare with all
care some 240 samples of paint, applying them to a test fence at
Arlington. The paints were all made up to have the same
"viscosity" as measured by the Stormer viscometer. Mr.
Gardner says of the tests, "The determinations were.fallacious.
What was actually done was to make some paints of a very low
and some of a very high yield value, although they all measured
up to the same viscosity. The result was that when some of the
paints were applied to the boards, they would flow and carry the
pigment particles down, leaving bare spots. Some paints
failed on this account."
According to Batschinski's Law the fluidity varies some
2,000 times as rapidly as the volume which is now used success-
fully in the dilatometric method, hence the viscometric method
should be most useful in chemical control work. Dunstan,
Thole and their coworkers have led the way in solving chemical
problems by means of viscosity measurement. They have
studied, for example, the keto-enol tautomerism, the effect of
conjugate bonds, the order of chemical reactions the existence of
1 Proc. A. S. T. M., 19, Part II, (1919).
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