CHRIS25
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UV Light and Blocking
Direct questions into google turn up nothing, physics sites force you through pages of of data without knowing whether or not you will get the answer.
It's a simple question that I can not find a simple direct answer to on the internet and would be grateful for the answer please.
What colours block UV light, the few tit bits that I have found suggest yellow and brown, yellow and amber. But this was a casual comment. I need to
use pigment inks to block UV, Black I know works, but I need to increase the block a bit with yellow or red? Or a mixture of both. (This has to do
with Potassium Ferrocyanide and ferric aluminium citrate). So some final concrete answer would be so appreciated. Thankyou.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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kristofvagyok
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In a photo lab we use red lights and red filters if the BW photopaper(extremely sensitive to UV) is taken out from the casing.
If the red filter is attachet to the photoenlarger, then the photopaper could be placed under it and could be modified a bit, while it won't get
damaged, but if any else light source will reach the paper it will get darkened in a minute.
So: use red.
Or if glass is needed, then use brown reagent bottle, they also block UV in high percent, but the absolutely best is the brown bottle coated with a
black polymer film.
But as I remember this question was discussed a few month ago....
[Edited on 2-9-2012 by kristofvagyok]
I have a blog where I post my pictures from my work: http://labphoto.tumblr.com/
-Pictures from chemistry, check it out(:
"You can’t become a chemist and expect to live forever." |
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bquirky
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the simple answer is definitely red..
Red things appear red because they absorb blue light. since UV is closesr to blue it will generally be absorbed more by red objects and reflected by
blue.
Blue/UV light has more energy per photon and This is indecently the reason why red things fade the most when outdoors.
look at any old shop sign that has red in it or plastic objects that get left outside like kids play toys the red always fades worst
Transparent glass or plastic blocks alot of UV but definitely not all. if you where trying to keep it out id suggest black paper/plastic or non
crinkled AL foil
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CHRIS25
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Hi Guys, I think I should havebeen more plain, I am not refrring to putting things in storage. I am actually referring to pigment ink. I mentioned
it above but not clearly enough, I want to block UV light with inkjet pigment ink, not resin ink. Black does a lot of blocking but not enough, I have
heard that yellow is the next best thing, but red and yellow mixed in equal parts is also a possibility. I was therefore looking for some science on
this rather than photographers' opinions.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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platedish29
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I didn't know paints could work in the invisible spectrum like that! Interesting information you provided. Why dont you try useing a UV lamp crossed
by paint and highlighter fluid in the other side?
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bquirky
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Can you use a laser printer ? people use toner for UV masking all the time making PCB Bords
perhaps you can print on the same peice of paper multiple times to get a higher pigment loading
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CHRIS25
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Hi Folks. Well firstly I can not get hold of a suitable UV set up, I am no good at electrics and so can not build one. I use the sun, it's free and
not complicated to set up. Facial lamps are ideal and reasonably priced but hard to get in Ireland, the lamps I have to order from England, so you
can see it's all a pain. Hence asking. I am printing on Transparency to get a negative, many tests have shown how matte black pigment ink works fine
(don't use gloss as recommended) but black by itself does not work in shadow areas where less ink is laid down for the UV to penetrate. I add yellow
to the black ink and this helps a bit. But I thought I would ask the question because Red also works - trouble is I did not want to be wasting
valuable ink, so thought someone might have a definitive answer, such as black yellow red, or black red+yellow in equal amounts, just to save me bit
of time and a lot of ink and transparency paper. bquirky, I don't have a laser printer, but this would not be good enough for the photograph.
[Edited on 3-9-2012 by CHRIS25]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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Quote: Originally posted by CHRIS25  | | But I thought I would ask the question because Red also works - trouble is I did not want to be wasting valuable ink, so thought someone might have a
definitive answer, such as black yellow red, or black red+yellow in equal amounts, just to save me bit of time and a lot of ink and transparency
paper. |
Frankly, without knowing the composition of the proprietary pigments and their dye spectra, it's hard
to say for sure whether one color will generically work at a different band.
Instead, I suggest that you make up a test page in Adobe Illustrator or somesuch, print a test page, and minimize the amount of ink you spend on
validating what you end up using. This is likely going to get you a good result faster than fiddling with parameters on single images. Since it's gray
scales that are the problem, you want gradient fills. You want one large bar for each pigment color; I assume that's four. Then you want a bi-gradient
square for each pair of pigments. That would be six. And then you want to be able to specify in the output stage that certain colors correspond
exactly to different pigments, which I am given to understand Illustrator supports for things like Pantone pigments, although I have no idea of the
details. Make sure to put witness marks, graticules, and numbers on the axes. After you've got the test page, expose it. You should be able to
determine what's acceptable by examination of the result. And if you're reusing a mask, you could leave a test page in the sun for a while to see
if/when you might have a problem with UV degradation.
(edit) Postscript : I seem to recall that some folks have developed UV-resist pigment inks for circuit board work. They're sold as DIY refills, as I
recall. Now I understand your reluctance for mail order, but it's entirely possible that you'll get an overall-cheaper process by using a purpose-made
pigment rather than pressing into service one that's not designed for it.
[Edited on 3-9-2012 by watson.fawkes]
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CHRIS25
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Funny Watson, I never thought about doing what you said. I have nine inks on my printer - that's a lot of combinations, but I know that I can
eliminate cyan and light cyan. So I will use yellow, magenta, light magenta the three blacks I think. The made for UV blokkers I am aware of,
unfortunatley that woul dmean re-designing the ink flow in a printer which of course would be a volcanic disaster. But your testing plan seems very
practical, why didn't I think of that?
[Edited on 3-9-2012 by CHRIS25]
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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watson.fawkes
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| Quote: Originally posted by CHRIS25 | | Funny Watson, I never thought about doing what you said. I have nine inks on my printer - that's a lot of combinations, but I know that I can
eliminate cyan and light cyan. [...] But your testing plan seems very practical, why didn't I think of that? |
I'd test even your cyan and light cyan, at least with single gradient bars. Not that I'd hold high hopes, but you might get lucky
that they happen to be UV-opaque. Perhaps with nine inks you might simply start with just gradient bars and do bi-gradient squares on a second pass
with the most promising candidates.
As for why you didn't think of, it's likely because the concept of a "parameter space" is ordinary to scientists and moreso to mathematicians. A
parameter space is the conceptual space of all possible combinations of the variable parameters in a given situation. In the case of your printer,
it's a 9-dimensional cube, that is, nine numbers each ranging from zero (no ink) to one (max ink). My idea is really to sample with parameter space
with some test patterns.
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platedish29
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You mean, many empirical x-Y% combinatory?
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CHRIS25
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OK, well, I decided not to waste expensive ink and valuable time by experimenting with all inks. I decided to concentrate on certainties and leave
futility behind. After studying a wee bit about the colour spectrum, I chose to take the Matte black which is a known UV blocker, albeit not 100%,
and it's the "not 100%' that is bothering me, so with matte black I added a combination of yellow and magenta, now exactly how much this is in
picolitres I will never ever know, but the arbitrary measurements are all that I need. It worked pretty well so far, but I need to do more testing.
Yellow and magenta are directly opposite Cyan, and since cyan is green and blue this makes sense as to these colours being very weak UV blockers.
Yellow and magenta make red, and red is opposite the cyan. So everything is going well. Just in case anyone is confused - I'm sorry - I am referring
to the RGB spectrum and CMYK physical ink. Not the colours that painters mix. Adding yellow and magenta to black I think gives brown, but I am no
expert on colours, and I guess it's not the brown that is important, more that yellow and magenta are high UV blockers on the colour spectrum. So
glad I didn't need maths for all this......
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
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ItsAChitzen
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How far into the UV do you need to go?
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