68degrees
Well-known
Ok then can we say that white reflects 100% and black reflects 0% and simply mix white and black together 82% black and 18% white?? Why cant it be this simple?
I want 18% middle gray what do I tell the paint guy at home depot?
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Ok then can we say that white reflects 100% and black reflects 0% and simply mix white and black together 82% black and 18% white?? Why cant it be this simple?
icebear
Veteran
First of all this clearly reveals that a metric system with ml might be a lot easier than parts of fl.oz or even oz by weight.
This always makes we wonder how NASA ever got someone to the moon.
As for your paint job:
Just get a the smallest jar blended they can do and look at it once it's dry. Weight rations of their proprietary paints (pigments) will never match any other formula, although the result might be pretty close.
And next time don't bother people 2 minutes before store closing with such questions...but the customer is always right 😎...?
68degrees
Well-known
Oh you must work retail to sympathize so much. hahahaa Hey I let her off the hook. I felt bad for her because she just cleaned the mixer. 😀
ColSebastianMoran
( IRL Richard Karash )
Take a look at Michael Tapes WhiBal. I use these and I find them very helpful.
A couple points from their site:
- For a metering reference you might want 18%, but for color balance you want more reflectance
- Gray? How do you know it's really gray and not warm or cold.
I like the WhiBal cards anytime the lighting is even slightly unknown.
68degrees
Well-known
Thank you colonel but I think thats for digitals isnt it? I wanted to calibrate some old manual film cameras and see how far off they are so i can compensate manually. Now I just want to figure out what mix of paint makes 18% reflectance. It cant be this complicated. How much white and how much black? Does anyone know?
venchka
Veteran
The surface you apply your newly mixed paint to will affect the paint's ability to reflect light. Add some gloss flatener. Latex or oil? You really have opened a ginormous can of worms.
What was the original purpose?
Wayne
What was the original purpose?
Wayne
venchka
Veteran
Here's a novel thought: Buy a Kodak 18% grey card. Like I did about a hundred years ago. I still have it. They are approximately 8x10. Use it to check your meters. Like I do.
K.I.S.S.
Information: Free for nothing.
http://www.bhphotovideo.com/c/product/27715-REG/Kodak_1903061_Gray_Cards.html
Wayne
K.I.S.S.
Information: Free for nothing.
http://www.bhphotovideo.com/c/product/27715-REG/Kodak_1903061_Gray_Cards.html
Wayne
Dan Daniel
Well-known
I have mixed custom paint colors for a variety of designers and architects, I can tell you that there isn't *a* formula for any color. White? I've probably made 150 different shades of what most people would be happy to call 'white.' Add in issues like metamerism and making neutral gray is not a simple matter.
Taking a color formula from one company to another? Means nothing. 'Red Oxide' is not a fixed color. Neither is black or thalo green or.... well, just too many variables.
I bet if you took the same gray card to three different places and they used a spectrometer to do a color match, you'd get three different grays.
I could go on, but think of this: Tri-X developed in D-76 1:1 at 68F/20C- how long to develop for? Imagine all the answers you would get. And then realize that color mixing has about four thousand more variables to deal with.
Taking a color formula from one company to another? Means nothing. 'Red Oxide' is not a fixed color. Neither is black or thalo green or.... well, just too many variables.
I bet if you took the same gray card to three different places and they used a spectrometer to do a color match, you'd get three different grays.
I could go on, but think of this: Tri-X developed in D-76 1:1 at 68F/20C- how long to develop for? Imagine all the answers you would get. And then realize that color mixing has about four thousand more variables to deal with.
68degrees
Well-known
Thank you all for your responses I really appreciate the discussion. As you know I am new and I have lots of questions so much thanks to all.
This is no longer about calibrating or possessing a gray card, it is about knowing what ratio of white and black paint will reflect 18% of the light shining on it. Nobody seems to know the answer. So far the best answers have been to have a known gray card scanned at a paint shop and they will mix the paint accordingly. This is what I will do but still it is gray, why is it so complicated? Black and white makes gray. How much black and how much white?
68degrees
Well-known
Shades of white is not white is it? When you make a shade of white, isnt one of the color codes simply 'white'? Thats the whtie I mean when i say white.
I once wanted white ppg lacquer paint for my car back in the day. I went in to the store and said I wanted white. He said there are lots of white which one do you want. I said I want white white.. He said there is no such thing they all have tints and hues in them. I said ok... I looked through the book and said I want this white whats the formula. He said well that has yellow, blue, white and a little black. I said to him, I want just the white without the yellow blue and black. Then he understood and made me a can of paint.
Is there really that much diffrence in white and black pigment? Is it just a matter of precision? How much could it be off by when mixing just black and white pigment from brand to brand? 1% ? 5%? Its hard to imagine ther being that much disparity.
willie_901
Veteran
68
I admire the free time you possess to pursue this topic.
I admire the free time you possess to pursue this topic.
68degrees
Well-known
hahaha great post!
watanabe
Newbie
What you seem to not realize is that color is a property of a material, ie cobalt/red oxide etc, and different companies produce the same materials to diff tolerances/specifications, heck even from batch to batch there can be variance. There is no "white paint" there are materials that have different reflective/diffusing/spectral properties.
68degrees
Well-known
How much difference between one manuctures black is another manufactures black. Or white. In your estimation. Do you think an 18% grey can be off by 5% from manufacturer to manufacturer or less than 1%?
Just curious.
jtm6
Well-known
You need to lower your expectations. The days of walking into a hardware store and talking to someone who can actually help are over, especially at Lowe's. The last time I was there, I had to teach the person in Lighting what a compact fluorescent bulb is (while I stood between two sides of an aisle with hundreds of compact fluorescent bulbs).
As others have said, just take a grey card and have the person match it. Expect the card to get trashed. Double check the final product before you buy it. Do your research beforehand to understand how to make true 18% paint. As venchka said, you probably want flat/matte. Don't go there with questions. Go there knowing exactly what you need. Beware of any "help". Listen to that inner voice. 🙂
bjornkeizers
Established
You know, I think this is turning out to be the best thread of the year... or at least the past week or so 😀
The pursuit of knowledge is its own reward. Many a times I've been wondering as to how or why things work or don't work the way one would expect. I salute 68degrees for his endeavors.
I googled it, and actually found another thread on another photography forum, where the poster asked the exact same thing - and got mostly the same answers
http://www.boards.ie/vbulletin/showthread.php?t=2056773486
They did mention that Dulux Ice Storm 2 paint would be close to 18% reflective properties, so you might get further researching that particular paint.
The pursuit of knowledge is its own reward. Many a times I've been wondering as to how or why things work or don't work the way one would expect. I salute 68degrees for his endeavors.
I googled it, and actually found another thread on another photography forum, where the poster asked the exact same thing - and got mostly the same answers
http://www.boards.ie/vbulletin/showthread.php?t=2056773486
They did mention that Dulux Ice Storm 2 paint would be close to 18% reflective properties, so you might get further researching that particular paint.
Peter_wrote:
Well-known
as others already stated your are mixing up "computer" numbers with the reflection properties of real materials.
so what would be 100% white? something that reflects 100% of the light. that wouldn't be something like a white colour at all, but something like a mirror.
even the same colour mixture can reflect different amounts of light. grey with a rough texture will reflect less light than a polished one.
and black? just think of a (well cleaned) black car. although black, the car body reflects a lot of light.
the only way to achieve a black "colour" would be to drill a very little hole which leads to a darkroom with highly light absorbing walls.
i illustrated that for you.
Unbenannt von picturing the cat auf Flickr
so what would be 100% white? something that reflects 100% of the light. that wouldn't be something like a white colour at all, but something like a mirror.
even the same colour mixture can reflect different amounts of light. grey with a rough texture will reflect less light than a polished one.
and black? just think of a (well cleaned) black car. although black, the car body reflects a lot of light.
the only way to achieve a black "colour" would be to drill a very little hole which leads to a darkroom with highly light absorbing walls.
i illustrated that for you.
Unbenannt von picturing the cat auf Flickr
Ronald M
Veteran
Whibal is not 18% grey, maybe 12%. It is a neutral grey meaning no tint so it is perfect for doing a white balance test.
Kodak 18% grey cards are for setting exposure and they do have some tint, but not much. You read the red channel on a color densitometer.
Whibal is an outstanding tool for what it is. I set all my digi cameras WB with it and they all balance perfectly. I save it as a preset.
I save the WB on the M8 & 9 as I feel it is more neutral. The Nikons change very little but I have a sun preset and a sun + Tiffin pola and can flip between them easily. The Tiffin polas all have a ghastly green + ? color cast. Leicas and B+W are a nice Neutral. I just screw them on and use them. The upside is Tiffins are dirt cheap in comparison and I can fix the WB from raw easily.
Kodak 18% grey cards are for setting exposure and they do have some tint, but not much. You read the red channel on a color densitometer.
Whibal is an outstanding tool for what it is. I set all my digi cameras WB with it and they all balance perfectly. I save it as a preset.
I save the WB on the M8 & 9 as I feel it is more neutral. The Nikons change very little but I have a sun preset and a sun + Tiffin pola and can flip between them easily. The Tiffin polas all have a ghastly green + ? color cast. Leicas and B+W are a nice Neutral. I just screw them on and use them. The upside is Tiffins are dirt cheap in comparison and I can fix the WB from raw easily.
Richard G
Veteran
as others already stated your are mixing up "computer" numbers with the reflection properties of real materials.
so what would be 100% white? something that reflects 100% of the light. that wouldn't be something like a white colour at all, but something like a mirror.
even the same colour mixture can reflect different amounts of light. grey with a rough texture will reflect less light than a polished one.
and black? just think of a (well cleaned) black car. although black, the car body reflects a lot of light.
the only way to achieve a black "colour" would be to drill a very little hole which leads to a darkroom with highly light absorbing walls.
i illustrated that for you.
Unbenannt von picturing the cat auf Flickr
Best picture posted on RFF for some time.
Roger Hicks
Veteran
First of all, 18% grey is nothing to do with the ISO standards for calibrating exposure meters. It's a Munsell mid-tone. That's all.
Second, a dead neutral grey -- neither 'warm' nor 'cold' can be surprisingly hard to achieve.
Third, what sort of light are you planning on using for your 'calibrations'? International White Light SA (2848K)? Or one of the various forms of 'daylight'? International White Light SB is 4800K; SC is 6500K; SD is 7500K.
Fourth, a diffuse 'pure' white is traditionally a block of magnesium carbonate which reflects about 90% of the light falling on it (a diffuse reflector can never reflect 100%)
The underlying lesson is this: don't look for precision that isn't there.
Cheers,
R.
Second, a dead neutral grey -- neither 'warm' nor 'cold' can be surprisingly hard to achieve.
Third, what sort of light are you planning on using for your 'calibrations'? International White Light SA (2848K)? Or one of the various forms of 'daylight'? International White Light SB is 4800K; SC is 6500K; SD is 7500K.
Fourth, a diffuse 'pure' white is traditionally a block of magnesium carbonate which reflects about 90% of the light falling on it (a diffuse reflector can never reflect 100%)
The underlying lesson is this: don't look for precision that isn't there.
Cheers,
R.