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The following is
a compilation of facts regarding slip-resistance
of floor finishes: The slip resistance of floor
finishes (coefficient of friction) is measured
on an apparatus known as a James Machine. The
results of the James Machine, when compared to
actual floor condition, becomes somewhat
nebulous, but it still remains the best test
available. The readings measure the static
coefficient of friction (slip resistance) and
give a numerical rating of 0.1 to 1.0 with 0.5
being the figure set as the limit of safety.
Readings higher than .5 are progressively less
slippery and hence safer. Numbers progressively
lower than 0.5 are more slippery and considered
unsafe.
A newer
generation slip resistance apparatus is the
Sellmaier tester unit which measures dynamic coefficient
of friction (slip resistance). An unfinished or
unwaxed floor is very often faster (more
slippery) than a finished or waxed floor. In
most cases the application of finish or wax
actually controls slip.
When
the coefficient of friction is
measured from a resting position, it
is called the “static coefficient of
friction” (SCOF). When it is
measured when the surfaces are in
relative motion, it is called the
“dynamic coefficient of friction”.
Measuring the dynamic COF is
difficult and requires a strict
laboratory environment for accurate
results. The James Machine would be
used in this situation under the
ASTM D-2047 standard. Almost all
portable and laboratory meters
measure only the static COF and most
measuring devices (slip meters)
refer to static COF based off the
ASTM C1028 standard.
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| The James
Machine, a laboratory only device
for dry testing only under standard
F489. This makes field testing
impossible. |
The
Sellmaier slip test
meter measures both
Static and Dynamic
coefficient and provides
a digital printout and
audit trail. |
For
decades, manufacturers of floor
finishes and polishes have relied
upon the ASTM D-2047 (UL-410)
standard for determining the
slip-resistant properties of their
products. This test method divided
products into two categories, those
whose dry Static Coefficient of
Friction (SCOF) was equal to or
greater than a 0.5 value and those
whose SCOF was below the 0.5 value.
Products that met the 0.5 or greater
value were classified as slip
resistant, while products whose SCOF
was below the 0.5 value were simply
not classified. For many, this
pass-fail approach created the
perception that products meeting the
0.5 value were “safe” while those
that did not were “unsafe.”
The higher the "Static
Coefficient of Friction"
the less slippery the
surface
Conventional
spray buffing is a major factor affecting
slip-resistance. Spray buffing hardens the
finish and thus speeds up the floor. There is a
definite correlation between hardness and slip.
Conventional spray buff (a mix of finish, water
and cleaner) lowers the coefficient of slip by
about 0.025 points thus speeding up the slip on
the floor. Today's modern spray buff and mop on
dressing compounds will control the slip on a
floor. After using a
Spray Buff or Mop on Restorer on a finished
floor, the slip index will usually read 0.05
0.075 higher on the James scale; slowing down
the floor (making less slippery).
Spray buffing is
a valid and economical method of floor
maintenance and is here to stay, but the proper
choice of chemical compounds is important in
relation to safety.
Water spillage on
floors creates an extremely hazardous condition.
Water acts as a lubricant between the floor
substrate and the bottom of the shoe. Spilled
water, condensation, food and drink should be
cleaned up immediately. Good quality walk off
mats should be placed at entranceways to prevent
rain and snow from being brought in by foot
traffic.
Residual mop
treatment film or residue from furniture polish,
metal cleaner and lubricating sprays will
greatly increase the slip on the floor surface.
Avoid overspray
onto floor. Clean up residues promptly using a
good heavy duty cleaner-degreaser. Dust created
by burnishing or dirty floors will cause a floor
to become more slippery. Sweep or damp mop
floors on a regular basis.
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