Removing residual colors on printers running Neutral K7 or K6 inks

Description of the problem:

You may see a color tint in your NK6 or NK7 printed images, particularly in the highlights. Even after running multiple print head cleaning cycles, the color tint remains.

In all cases where we have encountered this tinting problem, the cause is due to color ink that remains in the capping station of the printer, and may not be removed by running print head cleaning cycles. The remaining color ink in the capping station can transfer to the print head and then print onto the image. Below is a description of the problem and a solution is presented to clean out residual color ink. It is a very simple and effective procedure. It is also useful as a "print head cleaning" technique, especially if you see a nozzle check pattern become worse after running multiple print head cleaning cycles.

Background:

The capping station serves a few purposes in a printer. First, it seals against the print head when the printer is at rest, keeping the ink in the print head from drying out. Secondly, the cap is used in certain print head cleaning cycles: a small vacuum pump connected to the bottom of the cap pulls ink out of the print head and through the cap, removing clogs. The capping station sits beneath the print head, on the far right side of the printer carriage.

The cap consists of a black, rectangular raised rubber gasket, which surrounds a sponge (certain printers, such as the R800, R1800, R2400, and 7000/7500/9000/9500 series printers have two print heads and two caps). The sponge in the cap is porous in order to allow the vacuum pump to pull ink out of the print head during cleaning cycles, and also to allow excess ink to drain away from the print head and into the printer case. Occasionally the pores of the sponge may clog with dust, paper fiber, and paper coating fiber. If the sponge clogs it will not drain completely, or it will not drain quickly enough, and this will allow waste ink to contact the ink nozzles of the print head. When waste ink contacts the print head it can block nozzles from the outside of the print head, making it appear as if there is a clog, or else waste ink may transfer back into the print head nozzles, and then print out again. If there is still color ink in the sponge when this happens, it can print tinted ink onto the image, making it look like the Neutral K7 or K6 ink set is tinted. This staining is most apparent in shades #7 and #6 because they are so light and color staining will be more apparent there.

Even on a new printer, the cap may be completely clear of blockages, but color ink from the original ink set may stay in the sponge and not be removed by cleaning cycles. This small amount of color ink is enough to stain shades #6 and #7 of the K7 ink set.

You can very easily solve this problem by manually cleaning the capping station sponge. This procedure is easy to perform. The results are quite often immediate and long lasting. If the problem returns, you can repeat the procedure.

Procedure to clean the cap station sponge:

1. On desktop printers, press the "ink change" button and allow the print head to move to the left side of the carriage. On large format printers, use the keys on the printer control panel to initiate a "cutter replace" function to move the print head off the cap. On certain models of desktop and large format printers, the print head may only move slightly off the cap, rather than further to the left (and out of your way). In those cases, unplug the printer power cord and manually slide the print head more to the left.
   
   
2. Using a flashlight if necessary, look into the bottom of the right side of the print head carriage where the print head normally sits when not printing. The capping station is a black (possibly colored as well) rectangle, approximately 1"x2" (2.5cm x 5cm) in dimension (the actual size varies according to the printer model. Certain models of printers have two capping stations (for example, models R800, R1800, R2400, 7000, 7500, 9000 and 9500). Most other printer models have only one capping station. Some printers, such as the 7600 and 4800 have a second rectangular object to the left of the cap, which may be mistaken for a cap. However, this is just a sponge-covered hole leading to the printer case, which is used by the print head as a "spittoon" during certain cleaning cycles. If you are in doubt as to whether it is a capping station, press on it gently with your finger- if it is mounted on a spring loaded fixture it's a cap. If it doesn't move it's not a cap.
   
   
3. Deposit a few drops of Windex or warm water, onto the sponge or sponges, using a straw (or the tube from inside the Windex bottle), being careful not to spill any inside the printer. After the liquid drains away, redeposit the water or Windex. As you deposit more and more fluid on the sponge(s) you may notice that the sponge is changing color, or that the liquid drains out more quickly .
   
   
4. Fold a paper towel into a small rectangular pad, and use it to dab gently at the sponge(s), to remove inky liquid. To avoid damaging the capping station, which is mounted on a delicate fixture, push gently down and to the right as you dab the sponge. After dabbing on the sponge three or four times you will remove much liquid, although you will never remove all of it.
   
   
5. Next, dampen a few cotton swabs with water or Windex, and use them to wipe gently around the gasket around the cap to remove any buildup of paper or coating solids that may be there as well. Again, be careful not to move the cap off its fixture.
   
   
6. Return the print head to its parked position, plugging the printer back in if necessary. Run one or two head cleaning cycles, and print a nozzle check pattern. Once you can print a perfect nozzle check pattern, make a test print and verify that the color staining is gone.