Paint is mixed in a Pigment Laboratory, using eleven base ingredients and four catalysts. Paint mixing is person-specific; a recipe that works for one person will probably not work for another.
Each color can be represented by three numbers, giving the intensity (from 0 to 255) of each of the three primary colors: red, green, and blue. This triple is called an RGB value. The RGB value of pure white is (255,255,255), black is (0,0,0), red is (255,0,0), and so forth.
There are 142 unique paint colors that can be produced. When you mix a paint that has a given RGB value, the color from the list that is closest to that RGB value will determine what color paint you have mixed. For instance, if you produce a paint with an RGB value of (250,4,0), the paint will be red. Bug note: The game has been known to give out color requirements of Cyan and Magenta; these have the same RGB value as Aqua and Fuchsia, and so can not be produced (the paint will be named Aqua or Fuchsia, never Cyan or Magenta). If you get one of these, you'll either have to re-roll requirements (if possible), or devcall, unless it gets fixed so that the game accepts based on the RGB value and not the name.
There are eleven base ingredients, and each has a starting RGB value, listed below:
| Ingredient | Short | Red | Green | Blue |
| Cabbage Juice | cj | 128 | 64 | 144 |
| Carrots | cr | 224 | 112 | 32 |
| Clay | cl | 128 | 96 | 32 |
| Copper Ore | co | 64 | 192 | 192 |
| Dead Tongue | dt | 112 | 64 | 64 |
| Earth Light | el | 128 | 240 | 224 |
| Iron Ore | io | 96 | 48 | 32 |
| Lead Ore | lo | 80 | 80 | 96 |
| Red Sand | rs | 144 | 16 | 24 |
| Silver | si | 16 | 16 | 32 |
| Toad Skin | ts | 48 | 96 | 48 |
When you mix two ingredients, their colors are averaged according to how much of each ingredient is present. For example, if you mix two iron ore and one dead tongue, the resulting RGB value will be:
io + io + dt
Red = ( 96 + 96 + 112 )/3 = 101
Green = ( 48 + 48 + 64 )/3 = 53
Blue = ( 32 + 32 + 64 )/3 = 43
This color (101,53,43) is closest to SaddleBrown, so that would be the color of the paint. However, you will be unable to remove this paint from the pigment lab, since you must have added a minimum of ten ingredients (not necessarily unique) in order for the paint to be concentrated enough to use.
Ingredients are normally added in .1 deben quantities (when making one deben of paint), so if your recipe calls for one addition of el, you are actually only using one tenth of an earthlight mushroom; the remainder of the mushroom is kept in the paint lab for future use. If the paint lab runs out of a given ingredient, it will try to take another unit from your inventory.
Pigment labs can now be upgraded to make paint in batches of 10 or 100. The amount of ingredients used is also multipled by 10 or 100, so adding one el when making a batch of 10 paint uses an entire earthlight, and uses 10 earthlights when making a batch of 100. You must still add 10 ingredients to complete the batch of paint.
You may realize that it seems some colors, like white and black will be impossible; no mixture of the base ingredients will ever result in (0,0,0) or (255,255,255). However, there is a twist: some ingredients react with each other, to produce shift in one or more of the red, green or blue components of the color. Mixing together iron ore and copper ore will produce a different color that you might expect from the basic averaging. The magnitudes of these reactions for any given pair of ingredients are constant, but are also different for each person. The list of ingredients which react, however, is the same for everyone.
A crucial part of planned paint mixing is knowing your "reaction values", and how to apply them. See Paint Reaction Values for how to measure your reaction values.
The shift in the RGB values is constant for a given pair of ingredients, and is added on to the basic average. For instance, your io-co reaction might be to increase the blue component by 36, leaving the red and green components untouched. It will always be the same, unaffected by how much iron ore or copper ore is present.
A reaction between two ingredients is order-dependant. The shift produced by io, followed by co may be different than co followed by io. Also, a reaction between any two ingredients will only take place once, regardless of ordering. So, if you add io, co, io, only the io-co reaction will take place.
A reaction will occur whenever an ingredient is added to a mix containing ingredients it reacts with, and will react will all of those ingredients, subject to the above conditions. After five unique ingredients (reacting or otherwise) have been added, no further reactions will occur.
Finally, the reaction shifts are not included in the averaging when adding additional ingredients So, to calculate the final RGB value of a given recipe, average together all the ingredients, then add all the accumulated reaction shifts. For example, if you have a recipe cj io co io rs cl cr cr cr cr cr, the final color value will be the averaged RGB value of all the ingredients, plus the shifts from the following reactions: cj-io, io-co, cj-rs, io-rs, io-cl, and co-cl. Carrot does normally react with iron ore and red sand, but those reactions don't take place because by the time carrot is added, there are already five unique ingredients in the mix.
In addition to the eleven base ingredients, there are four catalysts: lime, potash, saltpeter, and sulfur. These have no color of their own (and so don't affect the normal average mix), and do not count towards paint concentration. They do, however, react with other ingredients, in the same way ingredients react among themselves. Among the catalysts, sulfur and potash react with each other to produce yet another shift. The other catalyst combinations produce no reaction of their own. Catalysts do count towards the number of unique ingredients for reaction purposes.
When striving for a particular color, most mixers will check the RGB value on a color chart (see above). Then compare that color to one of the 2-element averages to get a base mix. Then plan a catalyst / reaction strategy that gets you close, and begin experimenting.
Once you have a color, don't settle for that one recipe. Most recipes can be tweaked using reactions to avoid costly ingredients like rare mushrooms, silver, or red sand.
Research
Buildings
For the amount of paint you will need in your life, it may not be worthwhile for you to learn paint mixing. If that is the case, you will want to contact someone who does have a lot of recipes to mix your paint for you. You can probably track down someone easily enough, and the following painters have posted their recipe lists so that you can contact them for your painting needs (or get an idea of how to mix that color yourself).