Actual violet paint?

[Fandyus]

So I was wondering, does such a paint exist? A paint that would reflect no red, only violet and UV, so that it would actually appear dark violet when in sunlight, not purple (which would be red+blue reflective).

[Andrea B.]

There are violet pigments which are not made with a mix of red & blue pigments. Cobalt Violet and Manganese Violet are two such pigments. But then the question becomes: how does the camera record these pigments? As a mix of red and blue = magenta light.

[Stefano]

A quick search for the reflectance spectrums of those pigments shows that they also reflect some red, and thus I think that the purple you see (which isn’t violet) is actually blue + red (+ actual violet). This isn’t surprising for me, as blue pigments are also very rare (there are only a handful, with the recent discovery of YInMn Blue, and violet ones require even tighter absorption characteristics. The fact that the human eye is not very sensitive to violet light doesn’t help.

 

[I have to understand again how to make embedded links]

[Andrea B.]

Yes, but the point was that the violet pigment was not made with a mix of red and blue pigments.

 

And the other point was that our cameras would record spectral violet as a mix in the red and blue channels.

 

So even if there exists a pigment which "reads" as violet 405 nm (for example), it wouldn't matter that it was spectral when we tried to photograph it.

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Copy your link then, in the Editor, select the phrase to be linked and click the little chain icon next to the quote icon. Paste the link into the box which appears.

 

 

[Stefano]

I think what he wants is an actual violet pigment, (he said it shouldn’t reflect any red), and those must be extremely rare, if they exist at all. They would probably look dark violet, almost black.

 

A camera would see it as it would a violet LED or laser: it depends. Newer cameras should see it correctly: https://www.ultravioletphotography.com/content/index.php?/topic/4923-making-an-image-with-more-than-three-color-channels/&do=findComment&comment=50530

 

Thanks for fixing my link. I now noticed it is the Italian page, not too bad if you want to practice your Italian.

[Andrea B.]

While looking at those violet pigments, I became so fascinated !!! They are beautiful. Then fell right down the rabbit hole looking at more pigments and charts and paints. It was fun.

 

Anyway, the question Doug raised is within a larger one:  are there any pigments which produce a "pure" spectral peak with no secondary peaks?

 

Here is a slight reframing: With narrowband filters one could capture the cobalt or manganese violet peaks. Of course, finding a good narrowband violet-pass filter is just as hard as finding good narrowband UV filters. And you'd have to worry about the same leakage questions too.

[Andy Perrin]

Quote

 

Anyway, the question Doug raised is within a larger one:  are there any pigments which produce a "pure" spectral peak with no secondary peaks?

 

I really doubt it, Andrea, not even in visible light.