THE DATA FRONT

26 | hands on
Hands on
Vincent DiTrolio, president of the DiTrolio Flexographic Institute (DFI), troubleshoots common practical
problems encountered in flexo printing, in this regular series of articles.
Bring ink to press on color part 2
While performing training at flexo printing companies another
important area that is always addressed is ink management.
When ink management is properly executed, press side
efficiencies and waste will be positively affected. The topics
that are usually addressed include but are not limited to the
following: anilox volume standardization throughout press
room, inking system standardization (doctor blades on all
presses), ink mixing procedures, ink room inventory control,
and hand proofer to press correlation.
In Part One of Bring Ink to Press on Color we discussed
the importance of repeatability and efficiently matching color
prior to going to press and the steps of hand proofer to press
correlation. In this Hands-on article we will discuss ink mixing.
Tools needed in an ink room
With the minimum of the following tools an efficient ink room
can be properly managed:
1. A quality hand proofer with a doctor blade to ensure
consistent metering of ink volume
2. A gram scale to measure and produce test samples and an
appropriate sized scale to weigh and produce production
size batches of ink
3. An updated Pantone Guide
4. A color viewing booth to visual check color samples
5. A pH meter and a Zahn Cup to ensure proper ink balance
6. A spectrophotometer
In this procedure, we will first mix 100 gram test batch to proof
and then once the formula is correct, we will proceed to mix
batch sized appropriately for the run. The 100 gram formula
is achieved by converting percentage to grams: 1% equals 1
gram. Hence, if a formula that consists of 50% Trans white, 25%
warm red and 25% yellow would convert to 50 grams Trans
white, 25 grams warm red and 25 grams yellow. There are a
few other items that would make the process easier.
1. Fresh and uncontaminated ink. Mixing ink should not be
used for press runs. The ink is easily contaminated from the
pan or during wash ups
2. Squeeze bottles for the mixing colors. Using squeeze
efficiently add small amounts of ink to the 100 gram test batch
3. Small containers to mix test batch in
Steps to mixing ink:
1. Obtain formula for color needed. Note: Due to the different
pigments used by ink suppliers not all the ink formulas in a
Pantone Matching Guide will work in a flexo. Therefore, it is
best when possible to get the formulas from the ink vendor
2. Gather and verify mixing inks are at correct ph and or viscosity
3. Let’s use the formula for PMS 169
4.7% warm red equals 4.7 grams
1.6% yellow equals 1.6 grams
93.7% trans white 93.7 grams
Pour the appropriate amounts into a small container and mix well
4. Pull a drawn down of the sample. (Please refer to Bringing
Ink to Press on Color Part One.)
5. Confirm the draw down matches; if not document changes to
test batch of ink. See example chart.
6. Once the batch formula is correct, then convert it back to
100%; this is done by dividing individual part by total parts and
then multiply by 100.
Original formula 1st change 2nd change 3rd change Final formula
Warm red 4.7 grams
For example:
• The above formula adds up to 105 grams or 105%.
• Take the individual part and divide by 105 and then multiply by
100 for new 100% formula.
• Warm Red: 4.7 divided by 105 and then multiply by 100 equals
4.48% warm red
• Yellow: 6.6 divided by 105 and then multiply by 100 equals
6.29% Yellow
• Trans White: 93.7 divided by 105 and then multiply by 100
equals 89.23% Trans white
The new formula would be:
4.48% Warm Red
6.29% Yellow
89.23% Trans White
7. To verify the new formula, mix a 100 gram sample, and then
pull a new draw down with a hand proofer. If it matches, mix
ink for the run, and if it doesn’t match, recheck your data and
adjust accordingly.
As always keep it simple and document!
4.7 grams
Yellow 1.6 grams +2 grams +1 grams +2 grams 6.6 grams
Trans white 93.7 grams
93.7 grams
Feel free to contact me with any questions through Labels &
Labeling or at v_ditrolio@flexotraining.com
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