There are fifteen color channels available to armor pieces and articles of clothing, which basically divide neatly into five groups of three. Each of these five dyes provides a high-saturation color to each of a given grouping's three color channels (Primary: Red, Secondary: Green, Tertiary: Blue). The dyes are labelled accordingly in-game, so it should be pretty easy to get the gist of it.

Some armor and articles of clothing will combine multiple channels over the same surface. That is why I chose to stick with a very basic high-saturation RGB pallet for each grouping of channels. Thus, if you use one of these dyes, and see an aspect of the armor turn purple, you can be sure it's combining the Primary and Tertiary channels; yellow means it's combining the Primary and Secondary channels, etc. At least, that appears to be what is happening sometimes.

I made this originally for my own use, but figured that maybe others would find it useful too; people new to making dyes, for example. It could also come in especially handy if one person were requesting a very specific dye, meant for a specific armor piece or article of clothing, from someone who makes dye mods. That way both people can hopefully stay on the same page.

They appear in the tutorial chest, as well as being purchasable from Arron.

If you want to make a dye, but don't yet know how, I highly recommend AstralSprout's guide here on Nexus. As well as grabbing any dye mod which contains only a few dyes (or even just one) to unpack and use as a reference while reading through the guide. This mod, in fact, would work fine for that purpose.