Ink (re)mixing

Ink (re)mixing
Difficulty	Beginner
Duration	20 minutes
For series	All series
Tools	Pliers Electric drill/driver Paint mixing attachment Drill bit(s) Ink tube cap Gloves Spatula

The preferred method of mixing (or remixing) riso inks is directly in the ink tube—this can be done with any paint mixing drill attachment which is small enough to fit within the ink tube.

Background

There are two main reasons to mix inks:

1. To reconstitute separated ink back into printable ink.
   • So long as ink or oils haven't drained out of the end of the tube, the separated contents can be remixed and printed with again (though it is recommended to quarantine separated tubes until they can be remixed, due to the risk to the drum when printing with separated ink).
   • While new inks have a shelf life of 2–5 years (generally), a remixed ink will probably separate again within 6 months to a year, so they should be printed with immediately.
2. To mix custom color riso compatible inks—usually ratios of existing riso inks, though sometimes with non-riso pigments in Clear Medium (though the pigment itself must be quite small).
   • A tube of riso ink holds approximately 1000 g of ink, so mixing is usually done by weight.

Procedure

The process is very straightforward—open up the back of an ink tube, remove the plunger, insert the mixer, create a closure at the top of the tube, remix the ink, clean excess ink off the mixer, reseat the plunger, re-enclose the back of the tube. If mixing a custom color, the whole process can be done on a kitchen scale to mix an appropriate ratio of component colors.

Preparing for mixing

Ink mixing can be a very messy process, it's recommended to lay out scrap paper or a drop cloth, wear gloves (and maybe an apron), and take any other desired precautions. It's best also to have all the tools readily available, along with a trash bin and lots of rags to wipe up extra ink. All ink tubes to be remixed (or source tubes for custom colors) should be out and ready to go.

A "sealing cap" can be made by drilling a hole through the center of an ink tube cap, which is the same diameter as the shaft of the paint mixing attachment.

To simplify cleanup, plan on mixing a batch of inks all in the same session, working from lighter colors to darker colors. This way the paint mixing attachment doesn't need to be fully cleaned from one tube to the next—the remnants of the lighter inks will get swallowed in the darker ones.

Accessing the ink tube chamber

1. With the tube standing cap down, use pliers or a screwdriver to careful pry up the black plastic cage.

Once this cage is off, the ink tube must not be flipped cap-side-up and the cap must not be removed until the cage is returned. The cage helps hold the tube in a circular shape—without it the tube can easily deform, freeing the plunger and spilling the ink.

2. Use a pair of pliers to grab onto one of the fins of the plunger inside the ink tube—tilt it to an angle and pull it out of the tube. Excess ink stuck to the plunger can be scraped off back into the tube.

Measuring for a custom color (optional)

1. Use a rag to try and wipe excess ink out of the sides of the tube (though some will likely remain—the effort required to fully clean a tube is usually not worth the slight impurities in the mixed color from residual ink).
2. Place the ink tube on a kitchen scale and tare it.
3. Prepare the source tubes for plunging by removing their nozzle inserts. See ink tube transfer for specific instructions.
4. Plunge the inks into the tube in the appropriate ratio, for a total of 1000 g of ink.
5. The tube can be propped up in a paper jogger to knock out some of the trapped air from this process.

Mixing the ink

1. Push the paint mixing attachment in the ink tube, blade/fan down.
2. Slot the "sealing cap" onto the shaft of the paint mixer, flat side down—and press it into the slightly flared end of the ink tube to create a seal.
3. Attach the electric drill/driver to the paint mixer.
4. Run the mixer for ~90 seconds, moving the mixer up and down inside the tube.
5. Remove the electric drill/driver from the paint mixer, then pry the "sealing cap" off the end of the tube (this may require a flathead screwdriver or palette knife, as sometimes it's a very tight seal).
6. Use a spatula to scrape the excess ink off the paint mixer and back into the tube.

Resealing the ink tube

1. Press the plunger back into the tube, holding it at a 45° angle—and pushing it partially into the ink.
2. Flatten out the plunger inside the tube (the goal here is to trap as little air under the plunger as possible).
3. Use a rag to clean excess ink off the end of the tube.
4. Press the cage back onto the tube, clicking it fully into place.

The ink is now ready for use in the drum.