-1

I want to replicate a color scheme that is given in Hex codes (RGB, equivalently) - example here.

Given that I have red, yellow, blue, white and black paint, how am I supposed to systematically reproduce these colors? How can I determine the exact proportions of red, yellow, blue, white and black paint I should mix in order to get the colors shown? (Or any Hex-coded color for that matter.)

In any case I want to avoid mixing things "by eye". It seems too... dangerous given that suddenly factors like light can make a huge difference. I.e. if I am repainting after working hours, I may have to mix the paint on artificial light and may mix something different from what was initially planned. Also, if I am trying to stick to a pre-defined color scheme, then even minor differences in a particular color can produce major difference when combined with the minor differences in the other colors of the color scheme I'm trying to use.

3
  • It doesn't make sense though; the colorset you want is cyan, magenta, yellow, not red, yellow, blue.. And the color perception of a human is variable; one cannot simply say "a ratio of paint x:y:z will result in a color that looks exactly like #50D0FF when you place your painted surface next to your computer monitor" - colors don't work like that, your eyes don't work like that and monitors don't work like that
    – Caius Jard
    Mar 8 at 16:46
  • 4
    Yes, I'm afraid your question is rooted in a serious misconception about how color works. Even if you sidestep over to the CMYK color space, it's still not a simple formula and you will NEVER be satisfied with a translation, even if your light and monitor calibrations are tip-top. There is no substitute for eye matching. I know of a case where the Smithsonian mixed colors intentionally wrong to account for the artificial lighting in the display area. Mar 8 at 18:28
  • I found this website called sensual logic where you input what paint set you have and it tells you how much of each to use. Sadly I use crappy off brand Amazon paints but if you have cool paint sets it could help.
    – Idkman
    Aug 17 at 20:16
7

Re-think this. It's not going to work.

You're starting by eye anyway if you're picking from a colour on-screen. Unless your display is fully calibrated using a hardware colorimeter* you already don't know what colour it should be. Most consumer displays are set up intentionally punchy & over-contrast. This makes them look better in the shop. Setting your computer to the 'correct' profile provided by the manufacturer will not get you really much closer. You must use a colorimeter.

Ink/paint mixing doesn't use Blue, Red, Yellow, Black it uses Cyan, Magenta, Yellow & Black. The primary colours everyone was taught at school don't actually work in practise.

The conversion from RGB to CMYK requires not only your display to be accurately profiled, but also your output 'printer', because you are always expected to be 'printing' on a white substrate. Profiling, even on a CMYK colour-match system such as Pantone, depends also on the paper quality, reflective quality & absorbency.

Finally, you cannot mix under anything except calibrated light. If you don't have calibrated light, the best you can achieve is to go outdoors on a cloudy day. No domestic interior lighting is anywhere close to being accurate enough to attempt this task.
You also cannot know what colour paint will dry to based on a wet mix.

By the time you lump all those inaccuracies together you would be far better off going to your local paint store & selecting a paint chip. Get them to mix it. Their systems are fully calibrated to work from a wet mix to when the paint is dry.
Buy more than you need, because even on a fully-calibrated system, there will be batch discrepancies [this is why when you buy pre-mixed paint, you make sure all the labels say they're from the same batch].

*$£€ 250 for a decent one, already 10 times the cost of your paint.

You can convert RGB colour to RAL colour using such as https://rgb.to - however you are still not going to know if your RGB was correct in the first place. The RAL Colour Standard is used for information defining standard colours for paint and coatings and is the most popular Central European Color Standard used today.

4

Aside from the fact that a hex value is a proportion (each pair of characters represents a decimal quantity), you can't. Paint colors don't mix the way light does. This is why paint stores have libraries of pre-developed colors, plus a set of tints that are more specific, and not digital color wheels.

If you want to approach it mathematically, use a hex converter to get decimal values, then mix that number of parts for each color. Don't expect great results, though, partly since your RGB paints probably aren't exactly FF0000, 00ff00, and 0000ff, and also because compounds tend to change when brought together.

Related: How to convert RGB colors into CMYK (real paint colors)?

4

Paint stores can custom match any paint color using their equipment. The exact proportion of tints are based on the color sample you bring them and the base color of paint and sheen you select.

Not all paint base colors are exactly white, and they use more than just "red", "yellow", "blue" and "black" to make the color matches. It's been a bit since I last bought paint, but it seems to me the mixer at my local big-box store had upwards of 16 different tint colors to choose from in order to create the desired shade.

I'd suggest that you:

  • Sit down at your computer and generate a square of each of the exact hex color combinations you're after.
  • Print them on a high-quality ink-jet printer (preferably a photo-quality printer, on photo paper)
    • Alternatively, send it to your local "pharmacy" or other place that'll print photos for you. It might cost as much as $0.25 for each "picture" to do so (in the US, substitute local currency as required).
    • Note that unless you've color calibrated your monitor and printer, your printed sample probably won't be exactly the color shown on your monitor, but, unless you're a professional photographer, it will probably be close enough.
  • Bring the picture to your local paint supplier and have them use their equipment to make up a batch of paint to match.

Paint stores will custom mix colors (from either a predefined color chip from among the hundreds they have in stock or a color sample you bring in) for free, you just pay for the container of base paint you're after.

If you've already got paint that you're trying to mix from, I'd submit that you're going to be disappointed in your results, as the "red" you've got is probably not the exact "red" specified by a full FF (or 255) in the red channel as displayed on your monitor. Same goes for your "yellow", "blue" and even your "black". Note, too, that you're trying to mix from RGB as specified in the color picker on your computer and make that from R(YB)B in physical paints. How much yellow and how much green go into making that "blue" hex number you're looking at?

If you've already got the paint in hand, and you're painting a small area that will be fully covered by the amount of paint you've got, and you're willing to experiment, then by all means, approximate the proportions and go for it. (Make sure you use a paint shaker or a paint stirrer "bit" in your drill for a very thorough mixing.) Just don't expect to ever get another batch of paint to exactly match this one without bringing a sample to the store. Some paint will inevitably stick to whatever measuring container you use, so your measured 5ml (for example) won't put exactly 5ml of paint into your mix. You'll probably lose 1ml (give or take) in paint stuck to the measuring cup.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.