41 wrote:
> [email protected] wrote:
>
> > "Brittle" in this case is also one of those splitters. Wax smears
> > when it is rubbed upon and deforms plastically at room temperatures.
>
> I agree for e.g. beeswax but for paraffin I believe it would have to be
> a warm room. Surely out riding at e.g. 10-15 °C it is a lot more
> brittle than plastic.
I took a clear/translucent paraffin candle, and pressed an edge hard
with my thumb. The material yielded by producing white flakes of
various sizes, from snow-like to larger flakes, even some distance
(~1/8"+) away from the contact point.
I took a pin and dragged the tip across the surface, vertically and at
an angle, quickly and quasi-statically, with high pressure and with
minimal pressure. In all cases I produced white snow-like debris at the
edges of the track, and either ahead or behind the pin.
Quasi-statically, I could even build up a thin rooster tail of wax
snow.
I penetrated the pin vertically through the candle, quasi-statically
and quickly. In both cases I produced some snow at the entrance hole,
and large (extending ~1/2"+ away from the pin) white transverse sheets
(and perhaps clouds) inside the candle, as one might observe in an ice
cube that had cracked internally.
I held the pin transversely, and pushed the side against the candle,
either at an edge or against the side. Large white flakes were raised
and built up, extending far (~1/8"+) ahead of the contact zone.
I penetrated the pin through to an opposite side, and the pin emerged
with small scattered amounts of white wax snow or particles on it, but
no detectable smear. After every one of these tests with the pin, I
examined it for a wax smear, by etching a fingernail against it, and
rubbing with my fingers, trying to find a difference between the part
that had pressed against the wax and the part that had not. I never
found a detectable smear, only a few isolated wax flakes or snow.
I repeated all the same tests after first putting the pin under running
hot water (~130F, well below the melting point of paraffin), and
quickly putting the pin against the wax before it cooled excessively.
In all cases the snow or flakes were not produced until the pin had
cooled. For example, tranversely, the pin at first raised a translucent
slice, and then after cooling, raised white flakes as before. With less
initial pressure, it made a translucent indentation, and then rode upon
the surface after cooling. Upon the penetration tests with the warm
pin, the white sheets were not formed inside, until the pin was cooled
enough while inserted further.
I put my thumb under the hot water until the point of pain, and quickly
pressed it against the side of the candle. I was able to form a
translucent thumbprint on the surface and feel the wax yield. I took my
other (normal temperature) thumb, and pressed it as hard as I could
against another side of the candle, with my other thumb on top, also
exerting maximum pressure. I was unable to form an imprint on the
surface.
I repeated some of the tests with the pin with water droplets at the
contact site. Though the droplets made observation more difficult, it
appeared as if the snow and flakes did not form.
At the end of the tests, I had some wax snow or fine particles on my
fingers, which easily rinsed off under running water, which then
thoroughly wetted the surface of my skin.
>From these results, I conclude that paraffin wax is brittle at room
temperature (about 20 °C) or below, and malleable at higher
temperatures still below melting (40-60 °C). Whatever happens at the
interface, bulk temperature effects the state of the extruded wax
debris. At room temperature or below, snow debris seems to be ejected
away from the metal surface and the contact point. In hot climates, the
situation might be different.
