Measurement of the hardness of water-based paint

Hardness refers to the material's ability to locally resist hard objects from pressing into its surface. In the field of coatings, it is one of the most important energys to indicate the mechanical strength of the coating.
is used to show that the coating film is invaded by external objects local resistance, is to compare the degree of soft and hard coating indicators
China
.
different test methods and standards in the coatings industry, commonly used in pencil hardness, swing bar hardness and indentation hardness.
test method
pencil hardness
pencil hardness is a calibration coating hardness test method and measure system. By industry standards, the hardness of the pencil core is
13
grades.
from the hardest
6H
step by step by
5H
,
4H
,
3H
,
2H
the
H
, followed by
HB
in the right amount of hard and soft, and then from
B
,
2B
to the softest
6B
.
some companies, such as Mitsubishi Pencil and
F
, between
H
and
HB
.
testing methods have strict criteria, as can be found in
GB/T 6739-2006
color paint and clear
paint
pencil method to determine the hardness of the paint film

the swing bar hardness
swing rod damping experiment includes
K
swing,
P
swing and double swing, different swing bar hardness, will have different measurement results. And the three can not establish a common conversion relationship, measurement needs to indicate the type of application.
addition, in the measurement, due to a variety of external factors, the record should indicate the drying conditions and drying time, the temperature and humidity of the measurement, paint film thickness and so on.
double in the domestic wood paint hardness measurement application is more, because it measures the hardness of the paint film relative to the glass, so after the measurement should be recorded time converted to swing bar hardness value.
the hardness of the swing bar should also be carried out in strict compliance with the standard, as
GB/T 1730-2007
color paint and varnish swing rod damping test
the national standard document can pay attention to the public number to view and obtain.
indentation hardness
indentation hardness refers to the hardness assessed by the depth of indentation or indentation surface area by pressing the head into the surface of the material under the specified static test force.
can be adopted by the
Knoop
) and Fender (
Pfund
) press heads. The hardness value provided by the former is expressed in the number of Nup hardness (
KHN
) and the hardness value provided by the latter is expressed in the number of hardness (
PHN
). Among them, the accuracy of the Knup hardness is higher.
this kind of test application is relatively rare, the calculation formula is as follows:
other methods
in addition to the above-mentioned more standard test methods, some people will use nails or hard objects to cut, tap and other methods of testing.
method is more subjective, there is no corresponding standard, can not be used as an important basis.