Mixing letterpress inks: how to make 1600 colors from just 14 cans of ink
Watch our little letterpress video on how to mix your ink.
These are the supplies you’ll need to make all the colors in a Pantone Formula guide.
- the 14 Pantone Basic Colors (our premium letterpress ink starter kit has all these)
- Red (023)
- Pantone Black (mixing black)
- Blue (072)
- Transparent White (mixing white)
- Orange (021)
- Process Blue
- Reflex Blue
- Rhodamine Red
- Rubine Red
- Warm Red
- a Pantone Formula Guide (by itself here or it’s part of our premium ink kit)
- a scale that ideally measures in grams. Digital ink mixing scales are best. In the Boxcar shop, we use an Ohaus Triple Beam Scale. If you don’t have a scale, you could try a set of measuring spoons that have 1 tsp, ½ tsp, ¼ tsp and ? tsp. Your 1 tsp measure will equal 1 part. While not as accurate as a scale, it works.
- an ink knife
- a smooth mixing surface, like a piece of glass (ideal size is 8 x 10). For easier cleanup, put onto the glass a piece of wax paper, or freezer paper (with the glossy side up), or a large scrap of paper from your recycle pile.
Your Pantone Formula Guide tells you how much of each Basic Color to mix together.
Mixing inks starts with a Pantone Formula Guide. These guides are available on both coated and uncoated paper. If you’re printing on uncoated paper, use the uncoated guide. Older formula guides will show both percentage and parts. The newer PLUS formula guide has only percentages.
Turn the formula into grams so you can measure your ink.
Let’s say you want to mix Pantone 5645U, a lovely lighter olive (the U is for uncoated).
In parts, the formula is
- ½ pt Pantone Yellow
- ½ pt Pantone Reflex Blue
- ? part Pantone Black
- 20 ? parts Pantone Trans White
How do you turn these numbers into ink? You’re going to transform the parts into grams, with the goal of ending up with numbers more easily measurable on your scale. Generally 100 grams is a good amount of total ink to shoot for. Our scale does whole grams so we’re trying to get more whole numbers. We’ll going to multiple the above numbers by 2, or 4, or 6 until the numbers get nicer—keeping in mind the higher number you use, the more ink you’re going to make. In the case of Pantone 5645U, we’d multiply the numbers by 4.
- ½ part Pantone Yellow x 4 = 2 parts = 2 grams
- ½ part Pantone Reflex Blue x 4 = 2 parts = 2 grams
- ? part Pantone Black x 4 = 1.5 parts = 1.5 grams
- 20 ? parts Pantone Trans White x 4 = 82.5 parts = 82.5 grams
Alternatively, let’s take a look at the formula for Pantone 5645U using percentages.
- 2.3% Pantone Yellow
- 2.3% Pantone Reflex Blue
- 1.7% Pantone Black
- 93.7% Trans White
In this case, we’ll multiply things by 2 to make the numbers easier to work with. Multiplying by two means that we’ll end up with about 200 grams, more ink than we probably need, but we could always store the ink and use it again. Some would say if we use a formula with odd decimals (like 2.3%), we might mix up the ink incorrectly anyway and we’d have to throw it away.
- 2.3% Pantone Yellow x 2 = 4.6% = 4.6 grams
- 2.3% Pantone Reflex Blue x 2 = 4.6% = 4.6 grams
- 1.7% Pantone Black x 2 = 3.4% = 3.4 grams
- 93.7% Trans White x 2 = 187.4% = 187.4 grams
Measure your ink on your scale.
So now get out your scale. To keep the scale clean, we cut out 5 x 5 squares of paper ahead of time?we need as many squares as ink colors going into the mix. In the cast of 5645U, we’ll need 4 squares. Each square should be the same size. Put a clean 5 x 5 square onto the scale and then zero the scale out on that piece of paper. Using an ink knife, put an ink color on the paper, weigh it, then scrape the ink off the paper and put a clean paper down on the scale again. Use a different piece of paper and clean your knife completely (all five sides!) for each new can of ink you use.
If you are really adventurous, try your hand at mixing by eye or mix on the fly. May the force be with you!
Mix your ink completely so all colors are smoothly blended.
The motion is similar to scrambling eggs. Check out the No. 9 video on mixing ink at the top of this page. Your ink knife should move smoothly through your ink mixture. Printer tip: don’t add white to color. Add color to white.
Storing your letterpress ink.
Letterpress inks should last for several years if properly stored.
If you have a substantial amount of ink, store your extra ink in an ink can to preserve it for long term use. Don’t forget to label your mixture and whether it’s oil based or rubber based.
If you are storing oil-based ink (including metallics) in a can, try placing plastic wrap, wax paper, or anti-skin spray directly on the ink so it covers the ink’s surface. Then seal the can with electrical tape. This cuts down on the ink forming a skin.
If you have a small amount of ink to store, place the excess ink inside aluminum foil or wax paper and fold the foil or wax paper over many times to protect the ink. Label your ink and you can store many packets like this in a box for future print jobs. This works particularly well on rubber-based ink. It can be difficult to successfully store a small amount of oil-based ink because of how it skins.
Alternatives to getting the 14 Pantone Basic Colors
Try a basic ink starter pack: if you are happy printing with just a few inks and don’t need to match to a specific pantone color, we suggest the basic ink starter pack. Included are 4 Pantone Basic Colors:
- Warm Red
- Reflex Blue
- Transparent White (mixing white)
Plus Printing Black and Opaque White (printing white). These colors will allow you to mix a few hundred colors. When you need a color you can’t mix up, order a pantone custom ink (see below). Add the other Pantone Basic Colors gradually to build up your selection.
Custom ink mixes: if you don’t want to mix your letterpress ink yourself, you can always order custom ink too. Custom inks are are mixed scientifically at the Vanson ink lab just for you. Some printers prefer ordering custom mix inks for every job they print, though this can get expensive (and, since custom ink mixes come in 1 lb cans, you’ll have a lot leftover). We recommend custom ink if you’re going to be printing this same color ink over an extended period of time For instance, we ordered custom ink mixes of all the ink colors in our Smock and Bella Figura ink libraries so we can offer consistent color for all customer jobs. You know if you order a custom ink mix of 5645U, that when you need to order it again a year later, it will look the exact same. For very light colors, we tend to order custom ink mixes in our own shop because the formulas require such precise measurements (.2% yellow plus 99.5% trans white, etc.)