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This is what I came up with:

Colorant---BL---CL---FL---KXL
OZ--------3----0----0----7
384th-----54---176--64---0
Nope. Think base 384 math. You're not converting the mantissa back into 384ths ;)

Do you really need a gallon of N5 paint or is this simply an intellectual exercise?
 

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Harpmaker, I just realized that you are the one who took the Kodak credit card to the paint store. How do you know that it was truly neutral gray? I have purchased many 18% gray cards by various manufacturers and none of them match color wise.
 

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Harpmaker, I just realized that you are the one who took the Kodak credit card to the paint store. How do you know that it was truly neutral gray? I have purchased many 18% gray cards by various manufacturers and none of them match color wise.
The N5 paint that results from this formula is more neutral than my Kodak Gray Card, I only used the Gray Card to get close. I then used color theory and a spectrophotometer to get the paint more neutral by trial and error. IIRC it took me three tries to get the final mix to it's current level of neutrality.
 

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The N5 paint that results from this formula is more neutral than my Kodak Gray Card, I only used the Gray Card to get close. I then used color theory and a spectrophotometer to get the paint more neutral by trial and error. IIRC it took me three tries to get the final mix to it's current level of neutrality.
Hi,

I am acquiring a grading suite for colour correcting video, and have been trawling the web for info about neutral gray paint and where to get it, with surprisingly confusing results. You guys seem far more knowledgeable than those that are on the colour grading forums so I thought I'd ask you. First off I will show you what I am trying to achieve with the walls:

View attachment 43188
View attachment 43189

The first priority is that they are neutral (in L*a*b* colour space, a* and b* being between -0.5 and +0.5). Secondly, as I'd rather have 2 shades on the go instead of a rather bland 1, rather than have just 50% gray (in terms of lightness, not reflectance) I'd like to have two shades equally far apart from 50%, say 25% and 75% (thereabouts is good enough).

Addressing the first point:
a) research suggests that if I go to a custom paint mixer and ask for nothing but black, it won't actually be a neutral black; similarly for white
b) taking an 18% gray card for colour matching won't get me neutral either
c) I have a Gretagmacbeth Eye1 Display 2 spectrophotometer, but can this be used to assess neutrality? So far I've only used it for monitor calibration, by placing it directly on the monitor surface - but they emit their own light. How are you using your probe, is it designed to assess more than monitors?
d) If my Eye1 is of no use I plan to buy a WhiBal white balance card (which is certified neutral), then take a photo of the (dried) paint with the WhiBal in frame (using a single light source), correct the image so that the WhiBal is displayed in my software as being neutral and compare to the walls using both a vectorscope and the digital color meter you get in Mac OSX
e) Once I've seen how bad things are, is it a particularly complex trial-and-error process to get to within acceptable levels of neutrality? If this was video and it was too yellow I'd just add some blue, but I don't know if paint works that way
f) I could just take my WhiBal to a paint mixer and have them match that, but then presumably when I ask them to make it darker things will go awry again

Addressing the second point:
Research suggests that mixing white and black paint in a ratio of 1:1 won't actually get me a gray that is perfectly in the middle, rather I will get a shade of gray heavily biased towards black. Therefore trying 1:3 and 3:1 for 25% and 75% is similarly futile. Is this true? The exercise on this webpage suggests I'd be fine going with the simple maths: http://kaplanpicturemaker.com/ccc_painting_i/p-i_assignments

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Now, the lightness value of a WhiBal is in fact 75 so that would sort that one out, but then I'd still need to get the 25% shade. This assumes that I would like the look of 25% and 75% of course, the shades in the images look like they may be more around 50% than that.


Any insights or rebuttals to anything I've said above would be most welcome :T
 

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The attachments didn't show up. :dontknow: It may be because you didn't have 5 posts at the time or because you posted a bit too quickly after your fifth post.

a) In our experience, this is correct.
b) This is going to be hit or miss. Generally speaking, the equipment at most paint stores isn't that accurate as it has no real need to be that accurate. It just has to be close (within a dE of 3) for paint. You could get an accurate match but if you did it 9 more times, 7 of the 9 could be unacceptable.
c)You can use your i1pro to measure paint. :T We use a variety of programs to do it. I use BabelColor and/or CalMAN normally. But those cost money. You should be able to use the free software from X-Rite to get simple readings. I know that I used it for awhile but it does require some conversion as I believe it uses D50 as the standard. Harpmaker probably knows of some free software that escapes me right now. He'll chime in if he does.
d) No need as the i1pro will work.
e) When dealing with just paint, you are correct. It can be tough sometimes though, especially when you throw in something much more complex such as aluminum.
f) It may be tough getting that 25%. :huh:

Have you looked into the GTI Neutral gray paint? It's my understanding that that is what the pros use. It's a little bit expensive but if you're looking for accuracy, I'd think it should be there. I know that they make a N8 or a N7 paint IIRC. If you really want the darker gray as well, what I would do would be to add 'Mars Black' (Liquitex and Golden sell this in an artist acrylic) to the GTI paint until you get it as dark as you require - double checking for neutrality along the way.
 

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c)You can use your i1pro to measure paint. :T We use a variety of programs to do it

Have you looked into the GTI Neutral gray paint? It's my understanding that that is what the pros use. It's a little bit expensive but if you're looking for accuracy, I'd think it should be there. I know that they make a N8 or a N7 paint IIRC. If you really want the darker gray as well, what I would do would be to add 'Mars Black' (Liquitex and Golden sell this in an artist acrylic) to the GTI paint until you get it as dark as you require - double checking for neutrality along the way.
I'll look into those programs but I think you have the wrong idea about which probe I have. I have this one:

http://www.xrite.com/product_overview.aspx?ID=788&Action=Specifications

and I'm guessing you have this one:

http://www.xrite.com/i1basic-pro-2

I'm going to do some more research but I think i might be out of luck. Can you just hold your probe up to a wall then or do you need a sample on a piece of paper? And how far away do you hold it? And I'm guessing that ambient light isn't a factor.

I'm going to try one of the attachments again:

DR2.jpg

As for GTI that looks very helpful thanks, I can get it in N8 in the UK, I'll do more digging though to see if I can get N7. Wouldn't have guessed you could mix artist paint with wall paint successfully
 

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I'll look into those programs but I think you have the wrong idea about which probe I have. I have this one:

http://www.xrite.com/product_overview.aspx?ID=788&Action=Specifications
I just saw where you said you had an i1pro spectro. I missed the Display 2 part. You have a colorimeter, not a spectro.

I'm going to do some more research but I think i might be out of luck. Can you just hold your probe up to a wall then or do you need a sample on a piece of paper? And how far away do you hold it? And I'm guessing that ambient light isn't a factor.

I'm going to try one of the attachments again:

View attachment 43203

As for GTI that looks very helpful thanks, I can get it in N8 in the UK, I'll do more digging though to see if I can get N7. Wouldn't have guessed you could mix artist paint with wall paint successfully
A close N3 match would be S7500-N and a close N2.5 match would be S8000-N. You should be able to find a paint store that knows how to mix these up. If you need verification, you can send a sample to Harpmaker or myself and we can get a reading for you. :T
 

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Hi mintgreen! :wave:

You should be able to use your colorimeter to read L*a*b* values, a spectrophotometer isn't required for that. Ambient light isn't a problem when using the i1Pro since the meter is in contact with the surface being measured. I don't know about the Display 2, but I would assume this is how it would work for taking "spot" readings as well.

As for software, the i1Share that came with your colorimeter should work fine. I think that in the neutrality parameters you have set (that are the same as ours are for "perfectly neutral") it won't matter much what Illuminant is used. However, if you need more accurate readings you can still use i1Share to take measurements, but save them to a text file and use the Lindbloom spreadsheet to do the required math.

How much paint do you need? If you only need a small amount Golden makes neutral grays from N8 to N2. These are heavy body acrylic paints that would need to be thinned with water to use like a house paint.

I you truly require a* and b* values that are at or below 0.5 then you may have to adjust even the artist grays for stricter neutrality. This can be a royal pain, but once you get a light neutral and a dark neutral you should be able to mix these in any ratio and the result will still be neutral.

In my experience Mars Black is more bluish than Ivory Black, but even Ivory Black is cool and needs to be warmed with yellow a bit.

A less expensive N5 paint is Liquitex BASICS 'Neutral Gray Value 5', but they only have the one neutral shade.

The link you gave about mixing grays does not create neutral grays, but rather is about getting a range of gray colors to make paintings more interesting. Most people consider a true neutral gray as being ugly and "dead" and artists prefer to have some color in their shadows.

As for getting a true neutral gray from a paint store reading a Kodak Neutral Gray card, you kind of get the luck of the draw. I have had such matches that were almost dead on to ones that missed it by almost a full Munsell level.

When color correcting paint manually don't forget that you can only make a paint darker by adding tint to it (unless the tint is lighter than the color). This is why there are no (or at least none I know of) pure N10 white paints. To get a N10 white literally every component of the paint (vehicle, binder and tint) would have to be either perfectly clear or N10 itself.
 

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As for software, the i1Share that came with your colorimeter should work fine.
I don't know if we have a disk still that came with the i1 but if we do it's pretty well hidden, and knowing our former tech guys I'd say it's been binned. I downloaded the version listed on x-rite alongside my discontinued product, however I just can't get it to work either on PC or Mac. The computer recognises my device and I can run iMatch, but in iShare it only shows the icon for the new i1Pro not my model, and the 5 coloured lights beside it don't show up anything, not red or green. The monitor icon underneath shows 5 red lights beside it. I've checked through their 'help' but it really is no use at all and I just can't seem to get anything to happen. I've also tried that BabelColor program, and although it recognises my i1, again I can't get it to do a thing with it. All the Calibrate buttons are grayed out, I can't input text anywhere, can't get anything to happen. It is only the trial version but it's not much of a trial if I can't try anything out.

How much paint do you need?
2 small rooms (not large enough to fit more then 2 ppl seated pretty much) and possibly 1 slightly larger one for client viewings. 4 walls, 2 coats (possibly 3 around the monitor), with the 2-tone pattern, and possibly the ceiling just with a single tone (haven't much thought about the ceiling but it will have to be neutral too)

I you truly require a* and b* values that are at or below 0.5 then you may have to adjust even the artist grays for stricter neutrality.
Liquitex Soft Body Mars Black has a Chroma value listed as being 0.04, this should translate well surely? Or their Basics Mars Black still has chroma at a mere 0.12

In my experience Mars Black is more bluish than Ivory Black, but even Ivory Black is cool and needs to be warmed with yellow a bit.
Have you checked out Lamp Black by Winsor and Newton? It uses Carbon Black which I think is supposed to be very neutral

The link you gave about mixing grays does not create neutral grays, but rather is about getting a range of gray colors to make paintings more interesting. Most people consider a true neutral gray as being ugly and "dead" and artists prefer to have some color in their shadows.
I was using this to check whether simple math can be used to get certain lightness values of gray rather than being about neutrality. I got an impression from another forum that this wouldn't be the case, but I don't believe that now (assuming that the white and black used are of the same concentration or whatever, I doubt that it would take too much acrylic paint to significantly darken wall paint but I could be wrong)


I have acquired a 50% (...) gray card from ProSpecImaging that claims to be certified neutral with L*a*b*, though they don't give thresholds. I'll use this, a camera, Final Cut Pro's color corrector and OSX's digital color meter to compare levels with what I can get from a paint store. Real shame I can't get those thresholds for my gray card though.
 

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I don't know if we have a disk still that came with the i1 but if we do it's pretty well hidden, and knowing our former tech guys I'd say it's been binned. I downloaded the version listed on x-rite alongside my discontinued product, however I just can't get it to work either on PC or Mac. The computer recognises my device and I can run iMatch, but in iShare it only shows the icon for the new i1Pro not my model, and the 5 coloured lights beside it don't show up anything, not red or green. The monitor icon underneath shows 5 red lights beside it. I've checked through their 'help' but it really is no use at all and I just can't seem to get anything to happen. I've also tried that BabelColor program, and although it recognises my i1, again I can't get it to do a thing with it. All the Calibrate buttons are grayed out, I can't input text anywhere, can't get anything to happen. It is only the trial version but it's not much of a trial if I can't try anything out.
having said that, I remembered my grading monitor can take readings from the probe in both xyY and XYZ; however if I place the probe on anything that doesn't emit light then it just registers black, so I think this avenue is well and truly scuppered
 

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having said that, I remembered my grading monitor can take readings from the probe in both xyY and XYZ; however if I place the probe on anything that doesn't emit light then it just registers black, so I think this avenue is well and truly scuppered
Yeah, it sounds like your colorimeter isn't working properly in reflectance mode. Bummer. :thumbsdown:

Something I have always meant to do, but never did, was to contact Golden and Liquitex and find out what their tolerances are for color (or neutrality) from batch to batch.

Ivory Black is produced from burning bone, Carbon Black (AKA Lamp Black) is made from burning petroleum and Mars Black is made from magnetic iron oxide. House paints in the U.S. that are made with Lamp Black and a regular white paint (which is "warm") becomes a "cool" color when much Lamp Black pigment is added to it. Neutral gray house paints are made with a regular titanium dioxide white base to which is added Lamp Black to darken it, and also Red Oxide and Yellow Oxide pigments are added to counter the blue push caused by using Lamp Black alone.
 

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Hi there - resurrecting long dead thread as my first post. Found the site through a search for grey theater paint. I'm thinking of doing the entire area forward of our viewing area in 18% grey - crazy talk? The big question is which style of Behr ultra deep base for the formula - flat? Does flat/matte/eggshell affect the formula? There's also a dead flat option but no idea what that means and description doesn't help. If anyone's listening, thanks for the advice!
 

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Hello and welcome to Shack!:)

No, the various finishes (matte, flat, eggshell) do not affect the formula. Couldn't understand exactly...do you want to paint your screen with N5 or the surrounding area?
 

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Thanks! I had a gallon made up, will put it on next week after priming the new drywall. It's not for the screen (have a 20 foot chunk of white 1.0 reflective screen material ordered off ebay - had it set up before at old place, looks great. This time, will be 185" 16:9), it's for the entire room forward of seating - walls and ceiling. Going on the advice that it's ideal for a viewing lab and it's not so dark that it will be a total cave.
 

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Sorry for resurrecting an old thread... I have been looking for paint that is spectrally flat before running into this thread.

Has anyone tried Behr N520-5 "Iron Mountain"? When I look at the gray on their website by inspecting the code, it is rgb (117, 117, 117), which is the same RGB as the N5 18% gray's I've seen elsewhere. I am curious if a spectrometer would see it as N5.

I think it is a newer color then when this thread was created, so if this is N5, then it is probably easier to have them make that then to have them use this formula.
 
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