So, how much more effective is a 99.9% black compared to a modest 60% black for our purposes.
I say, not much, in fact the 99.9% is an insignificant improvement for our purposes.
So, how much more effective is a 99.9% black compared to a modest 60% black for our purposes.
I say, not much, in fact the 99.9% is an insignificant improvement for our purposes.
60% black, Jac? ... (hmm, a rhyme)... That means twice as bright as a gray card, or for sake of all the bearded ones, Zone VI. "Black" generally implies something a lot lot darker than that ! What kind of purposes do you have in mind? Inducing flare? ... Or are you merely referring to pigment load per volume? Generally, the more pigment in relation to binder, the more fragile the surface is, and the harder it is to retouch. Deep flat blacks are simply the most difficult to make in this respect. I'm not a Hassie guy, but does someone here remember when they introduced "papilli" coatings to inhibit internal
reflections. I heard some horror stories about it. Maybe new nano technology will bring an improvement.
Originally Posted by Drew Wiley
Yep, I messed up on that. Thanks for the correction.
Jac, the best black coatings use carbon as the pigment, and from there the differences are the binder and the surface structure of the coating. Carbon black has a uniform 6% (I think... as I get older I forget more and more) reflectivity across the visible spectrum. Binders only increase the reflectivity from there. Krylon Ultra Flat Black if properly applied has about 7%. You’d be hard-pressed to improve on that for anything less than $100 an ounce.
Those are direct measurements that I made and verified independently (you used to be able to dig and find the actuals if you knew where to look. The link is gone now) about 15 yrs ago. I measured because it was that important at the time. Basically Krylon UFB is damned good stuff:.. any other relatively cheap coating was 1 or 2% higher including flocking paper and stuff like that. In the infrared (near and far) it is about the same.
Newly made large format dry plates available! Look:
https://www.pictoriographica.com
Aside: I happened to have a black so-called military type belt pack in my darkroom while I tried some IR binoculars. The pack was brilliant white! I laughed out loud imagining all the play-acting preppers loaded up with such crap.
(The pack happens to be perfect for holding five 4x5 holders.)
The other funny thing was when I tried to photograph the SR-71 Blackbird at the science museum at night with my point and shoot digicam, and the IR auto focus refused to focus on the nearby finish, probably due to anti-infrared compounds in the paint... :-)
Steve K
Reflectance can also be significantly affected by the degree of humidity and temp at the time of drying - too slow a dry generally means the binder will have more gloss. A lot depends on the solvent, but Krylon being a consumer product, it's
not formulated ideally for this kind of application.
What to you make of its top-side red lines? To identify by satellite?
No-step areas
Newly made large format dry plates available! Look:
https://www.pictoriographica.com
Interesting! The lines are not on all SR-71, but I suppose the crews are adequately trained. They might also lay down temporary stripes for maintenance. Whatever. My imagination soars with the SR-71. I guess you have been close enough to one to see how very tiny the cockpit(s) are, then look back to the engines! It almost makes me dizzy.
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