Damascus question

hermit dave

hermit dave

Joined
Jul 19, 2011
Messages
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So, i picked up a Cold Steel Night Force (my 1st damascus knife), and I noticed that the reflection of a white LED bulb is orange/red when viewing the blade at one angle and blue/green when viewed at another. Anyone know why it does this?

BTW, a great knife. Probably the most refined folder in their current lineup (they even mirror polish the lockwork internals)
 
I knew I should have paid more attention in Physics. As far as I can tell your question is not Damascus-specific.
 
Don't different elements reflect different wavelengths of light? Being layered steel that would be what causes this. I don't really know. I know a similar system is used to identify gases in deep space.
 
hermit dave said:
So, i picked up a Cold Steel Night Force (my 1st damascus knife), and I noticed that the reflection of a white LED bulb is orange/red when viewing the blade at one angle and blue/green when viewed at another. Anyone know why it does this?

BTW, a great knife. Probably the most refined folder in their current lineup (they even mirror polish the lockwork internals)
Click to expand...

Have one too but didn't notice this. Will have to dig it out and see...
 
I read this somewhere on the web when someone was asking about Identifying Real Damascus steel, ( Check it closely, try to reflect light with it: real damascus should have visible layers with different light reflection.)
 
The only thing that would change the colors would be a change in refraction not reflection right? Is there some kind of coating over the steel?

Edit: Found this online,

If you make a reflecting surface out of a shiny (colorless) metal then it reflects all the wavelengths of light uniformally leading to no change in color of light.

If you have another shiny metal surface which is colored (e.g. copper, gold etc.) then it means they don't reflect light uniformally in the visible range.

One may see the reflection spectra of the surface to deduct which wavelengths are preferred in reflection. If the surface appears yellowish, you know it doesn't reflect bluish light in visible spectrum (as is the case with gold/copper)

The final color you see is the mix of various wavelengths of light in their respective strengths (You may read more about "colorimetry" to understand how human eye perceives colors)
Click to expand...
 
Night Rider said:
I read this somewhere on the web when someone was asking about Identifying Real Damascus steel, ( Check it closely, try to reflect light with it: real damascus should have visible layers with different light reflection.)
Click to expand...
That's just referring to to viewing the layers of steel, which is different than what the OP is describing, unless I am misunderstanding.
 
It's probably something to do with the finish. If it is a brushed finish, as opposed to a mirror finish, the minute striations in the individual layers would absorb and reflect different wavelengths from different angles. This is somewhat different from refraction, which is the separation of light into its spectral colors. It has nothing to do with the layers, but rather the smoothness(or lack thereof) of the surface.

I think....
 
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