metalresearcher - 16-12-2011 at 09:02
According to Wikipedia this is 525oC. I tested it with an electric furnace with two thermocouples (K and S) in it one of it (the S one) sheathed and used or
the Sestos temperature controller set to 540oC.
When the temp is 530oC I still see the sheathing very dull red (in a completely darkened room). The problem is that the Kanthal wires are always
hotter so the give an extra glow, so I have to turn off the electric heater and then let it cool so that I see no darker objects (the thermocouple
with its sheathing) and look into the furnace (covered with well insulating brick with a small peephole covered with stove glass).
Not the best way to calibrate, but it works.
UPDATE: I still saw a very very dark gray and read the display and saw 510-520oC. Gray ? Yes the cones of the eye are too insensitive to detect 'red'
but the rods of the eye still work monochrome.
Any ideas on this ?
[Edited on 2011-12-16 by metalresearcher]
[Edited on 2011-12-16 by metalresearcher]
dann2 - 18-12-2011 at 12:09
I have seen the 'gray' colour in subdued light (inside on a dark day) @490 degrees C. The same piece of material viewed in the dark showed up a very
dull red.
Dann2