Impressions - August/September 2023 - 43

Operators should be checking for quality
throughout the production run. Image by
Zamrznuti tonovi - stock.adobe.com
for cracking. Shirts printed with athletic plastisol or spandex
ink will stretch 25 percent even if they are not fully cured.
This test is not conclusive by itself.
7. Cellosolve Acetate Test: Open a shirt to the inside and
find an area that has some of the printed colors on the front
of it. Use a dropper to put a few drops of cellosolve acetate
behind the print on the inside of the shirt. Take a piece of
clean white fabric and squeeze it to the printed area on the
outside of the shirt where the cellosolve acetate has been
applied. Hold with pressure for two minutes. Remove the
piece of fabric and inspect for any staining. If there are no
stains, the ink is probably cured. Some ink colors are not
very stable and do stain slightly even though they are cured,
especially red.
If a print fails any of these tests, all the shirts that have been put
it is scorched. Run the tests again and compare the results. You
will now have the results of a print with ink that is definitely not
cured and one that definitely is. Hang these examples on the wall
so they can be used for comparison by others. Note: the last three
tests are for poly/cotton shirts. Again, these tests need to be run
before the shirts are printed.
After that, tests should be conducted at the following times:
first thing in the morning; just after the first break; just after the
second break. Long jobs run on automatic presses should be tested
on an hourly basis.
The following is an outline of the testing information to be
entered and the procedures to be used for the tests:
1. Temperature Setting of Dryer: This will probably not
be changed often.
2. Belt Speed: This will be changed often to allow either
more or less heat to be absorbed by the shirt. Slower speeds
= higher temperatures; faster speeds = lower temperatures.
3. Relative Humidity: This is very important for use in the
future. Eventually there will be a history of documented
settings to be able to adjust the dryers quickly as the relative
humidity changes so curing the ink is not a problem.
4. Thermo Probe: Use an Atkins probe and record the time
the probe reading was above 305°F and the maximum temperature
reached. The temperature should be 305 or above
for 10 seconds or longer. A fresh shirt should be used each
time this test is conducted. The same shirt can be retested
after two days. Shirts that are used prior to that period of
time may give a higher temperature reading than a shirt
that hasn't been put through the dryer, since the moisture
content has been removed.
5. Crock Test: The test sample should be placed on the Crock
meter with the long dimension in the direction of the rub.
Attach a clean crock cloth to the Crock meter and run 10
cycles. Evaluate against the AATCC Chromatic Transference
Scale (0-5 where 0 is total fail and 5 is no crock). Pass
is normally 3.5 or better. If you don't have a crock meter,
take a piece of light-colored fabric and rub it over the print
and check to see if any color rubs off. Some might, but an
excessive amount is not a good sign. Do not rub too much.
One or two medium pressure rubs will do. This test is not
conclusive by itself.
6. Stretch Test: For a standard plastisol ink to pass the stretch
test, it should be able to stretch about 25 percent without
cracking. Make a mark 4-inch-wide on the folding tables
and another mark at 5 inches. Hold the print to the 4-inch
mark and stretch it to the 5-inch mark. Examine for cracking.
This test is for shirts printed through a coarse mesh. Jobs
printed through a fine mesh will be very difficult to check
through the dryer since the last passed test need to be put through
again. If you're doing a long run job, it may be desirable to do
tests on an hourly basis so the number of shirts that would have
to be put through the dryer in case of a problem will be minimal.
There are many tests that companies perform to check if the
ink on a garment is cured (fused) properly. Most of these are quick
tests that are not completely reliable but are good for quick results.
The best test and most reliable is a wash test. Unfortunately, wash
tests take a lot of time, but if the job is big enough or the client
is important enough, then doing a wash test is the most reliable
way to check the ink and make sure it is fully cured.
Continuity between prints is an issue when printing certain
types of designs, especially four-color process since contamination
is an issue and changes the colors of a design. There isn't a specific
test to perform in order to control this but there are ways of setting
up, so the prints are viewed and inspected on a regular basis.
There should be an inspection station at the back of the dryer.
The inspection station should include a table with a controlled
light above it. One suggestion is a GE Kelvin 50 bulb, which is
supposed to simulate daylight. There should also be a rail across
the station so a sample or control-printed garment can hang from
it. A roll of colored tape can be used to make out where there
is a pin hole or some kind of misprint or damage to a garment.
Measuring tape to check the placement of a print is also useful.
For runs where colors can shift easily, such as a four-color process,
the following can be done to see if the colors are shifting: buy a
piece of cork or Gray Wall that is about 18 inches high and about
10 feet long and mount it to a wall. Take the approved print, fold
it in half the long way and mount it at the extreme left or right
of the cork or Gray Wall.
During the run, take a garment every 50 to 75 prints, fold it
the long way and see how it matches up to the control-approved
print. If it matches, continue printing. If the colors are starting to
drift away too much, either add fresh ink to what is in the screen
or remove the ink in the screen and add fresh ink. If this is done
on a regular basis, it is unlikely that the colors will drift too far
apart. If too many garments are printed before inspection, it is
very possible the ink will have to be changed.
The most important thing about a quality control system or
quality assurance system is that it gets used for every job, every day
no matter who the client is, even if it's an in-house job. Quality
is king if you want to land high quality clients. 
Veteran decorator and screen-printing guru Charlie Taublieb
is both the principal of Taublieb Consulting and a regular
Impressions Expo conference program presenter. His new
book, The Screen Printers Handbook & Survival Guide, is
available either digitally or in the form of a spiral-bound
book at taubliebconsulting.com.
Aug./Sept. 2023
P.43
http://stock.adobe.com http://www.taubliebconsulting.com
Impressions - August/September 2023

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