As per some requests, I found a couple hrs tonight to just type away hehe. This is how I approach matching a particular color, but there are many methods to do this. I'm just a very technical person and want to know exactly how everything works and why. First you have to start with the basics, the fundamentals. The 3 primary colors Blue, Red and Yellow. : these are the colors that you cannot mix from any combination of any other colors. The 3 secondary colors Orange, Violet, and Green. : these are a mix of 2 primary colors. For example: mix primary colors yellow and red to make secondary color orange. These 3 primary and secondary colors make upthe basics of the color wheel. This is in my opionion, the primary tool the color wheel serves, as for choosing paint to mix/match a color is dependant of factors of your physical paint. What I mean by this is something called "color bias." For example: Cadmium red is an orange red, and will be bias towards yellow. There is no such thing as a "pure red" or a pure "blue" they don't exist. Every paint brand uses different pigments to acheive their color, and use different colors to make their particular color. Take the color crimson for example. You can mix this several different ways. Typically, crimson is mixed using blue and red, therefore will have a bias towards purple. I have used green to tint back the blue so its not as cool before. This would then have a bias towards yellow, IF there is enough yellow in the way your green is made, . There really is no exact formula and this is why it's critical to stick with the same paint system and learn it well. This is the only way you will ever be able to match a color by eye. Tertiary colors These are the mixtures between the 6 colors mentioned above. While important, its not as important for mixing colors. This lends a hand more towards coming up with your color palette or scheme on an original piece. Analyzing the 3 properties of color To accurately mix or match a color you need to analyse it's properties. This takes a long time so don't get frustrated, it all comes with practice and understanding. The 3 properties are as follows; Hue, Value, Saturation Hue: Best way to explain this is it translates the color. The sun has a yellow hue, literally means if you had to mix the color with the closest pure color you can think of, as in red, orange, yellow etc, but not necessarily bright yellow. Value: How light or dark the color is if it was a black and white photograph. This is one of the most important factors in mixing accurate colors, but one of the hardest to master. If you have ever notice a painter squint, one of the reasons is squinting helps the eyes'black and white receptors to make better value judgments. Saturation: how bright, or intense the color is. It's sometimes referred to as Chroma or Intensity Now on with the fun part and what we are after. How to match that freaking color! Visual representation is best for this part. I don't have any paint near me at the moment, so I will just attach pictures found on the internet that hopefully most monitors will view the same. I will walk you through analyzing the 3 properties I just mentioned, and put them to practical use. Target Color First Step: analyze the hue - what color is closest on the color wheel? Lets go with the obvious choice of yellow. I've found that most yellows have an orange/red bias. Looking at the yellow against the color wanting to match, you can see that it's too yellow and the target color has a much more orange hue to it. I would add a little bit of red, which most I've found have a bias towards yellow. This should be mixed until an yellow-orange has been achieved. Second step: analyze the value - How light or dark is it? If you find your mix is too dark, you can add white, if its too light, we can add the complementary color. Looking at the color wheel to see what is opposite the yellow-orange we have mixed, you will find a dark blue-purple. Third step: analyze the saturation - How bright or dull is it? More than likely it will be too bright, so add just a little touch of blue-purple to tone it down. Be careful with using darker colors as they are stronger and tint easily so add very minute amounts and keep mixing until desired color is achieved. The final picture attached shows how purple added to yellow orange will darken to a point, then shift towards purple. controlling this slowly is key to getting a spot on color match. As you add very small amounts of blue-purple to your mix, you should eventually hit the target color. Hope this helps someone, I've tried to simplify classic teaching I received years ago when doing oil paintings. The other method is what helped me figure out the bias of the paints, but takes longer to catalog in your head and remember on a regular basis. This would be just mixing colors and see what happens. You will noticed a lot of artists, especially those in the auto industry that have to churn out large amounts of work quickly, will stick to the same color theme for most things. This is because they know their colors well, how to mix and match them, and this comes in handy to always have supplies ready, assisting in speed of job completion, and repairing damages and scratched airbrush work without having to redo the entire thing, saving you time, and making the customer freaking happy as hell. Well sometimes, you can't please everyone in this day and age.