Print Ringspun or Open-End Tees?

T-shirt

Ringspun has a slightly softer feel and appears to be better for printing
a process job for a modestly higher price per shirt.  Which is the better
shirt?  That is where the mystery begins.

Screen printers and their customers may notice the fibers of the shirt coming through
the ink giving the image a faded or fuzzy look.  This problem may not
be apparent when the image is first printed, but rather after multiple washings.  Many
printers believe this problem occurs more with ringspun.

When the ink appears to fade after being washed, most screen printers would conclude
the ink was not fully cured.  If under curing is the cause, the fading
would be inconsistent, that is, the ink would appear to fade in some areas,
but not others.  An image that is faded consistently and has fibers coming
through the image is not a curing problem.  The problem is fibrillation.  Printers
may associate this problem with ringspun, but actually the problem can also
occur with open-end yarn.

The potential for fibrillation and a screen printer’s ability to control the problem
should be considered when deciding which shirt is better.  Shirt selection
has a lot to do with the chance the fibers will break loose from the ink when
the shirt is subjected to rubbing from repeated washings.  Fibrillation
is more noticeable when the ink colour and shirt colour are contrasting colours.

A more coarse yarn is more likely to produce fibrillation also.  The length of
individual fibers and size (count) of the yarn are key concerns when selecting
tees to print images you can see, but hardly feel.  A higher numerical
count is finer and better for printing.  The higher numerical count means
there are more stitches per inch, more manufacturing time, and a higher cost.  That
is the ringspun being compared to the open-end tee.

A light weight cotton shirt is less susceptible than a heavy weight cotton shirt to
fibrillation.  Polyester content shirts are also less likely to produce
fibrillation, because polyester does not have fibers like cotton.  Polyester
also doesn’t absorb perspiration like cotton or allow colour to be reproduced
as accurately on process jobs as cotton.  So for four colour process,
printers will want 100% cotton.

Comparing and selecting a shirt, then, requires examining a number of issues beyond whether
a shirt is simply ringspun or open end.  To these criteria the manufacturers
and distributors will add how the garment is stitched, style, cut, shrinkage,
available colours and availability.

When the comparisons are completed, and the shirt is selected, the screen printer may
still be faced with printing, for example, a heavyweight 100% cotton shirt
with ink colours that contrast sharply with the shirt colour.  Of course
the consumer wants to see the image, but not feel the ink.

Fibrillation is more likely to occur when the ink deposit is thin, or soft hand.  A
heavier deposit may cover the fibers or fuse to the garment with the fibers
laying down and sufficiently covered so the repeated rubbing will not break
the fibers loose from the ink.  Process images have such small dots of
ink that insufficient ink may be deposited to hold the fibers down.

There is a solution, however.  Actually there are several solutions.  These
more demanding situations show the value of better printing materials and methods.  One
is the retensionable frame with mesh stretched at very high levels, that is,
45 N/cm2 and higher.  High tension helps to prevent driving ink into the
shirt.  Ink should be cut off and deposited on the top of the shirt thoroughly
covering the fibers.

A sharp, square edge squeegee blade is important also.  In fact, squeegee blades
should be sharpened daily to be sharp.  Similarly, the blade should have
a hard center like 75-92-75 durometer so that the squeegee angle will be consistent.  A
bowed blade will deflect ink down into the shirt rather than cutting off an
ink deposit thickness that is determined by the squeegee angle, squeegee speed,
mesh count and capillary film thickness.

Capillary film is fundamentally different from liquid emulsion.  The stencil is
a separate layer under the mesh.  If the capillary film is applied with
only water, and not squeegeed into the mesh, the thickness of the stencil is
much more predictable than squeegeed film or liquid emulsion.  Typically
process jobs are printed with 20 micron capillary film, but 30 micron may be
more appropriate when fibrillation is a concern.  That extra 10 microns
of ink sitting on the surface of the shirt provides extra protection without
creating an objectionable hand, or feel, to the print.  Capillary films
on very tight screens produce smoother prints than soft screens or liquid emulsion.

An off-contact distance of .03” allows the mesh to peel off and produces minimal mesh
distortion.  The squeegee pressure must be controlled to place the ink
on the surface rather than driving the ink into the open areas of the weave.  The
texture of the shirt should be bridged over with ink rather than used like
sandpaper to wipe ink off the bottom of the screen.

A uniform .03” can be achieved easily with T-shirts by purchasing a piece of Plexiglass
.06” thick that covers the platen.  T-shirts are typically .03” thick,
and that leaves .03” for the off-contact.

Consistency also requires that the platen not move at all when pushed downward.  The
instability of such movement downward is a very common industry condition that
almost always contributes to driving ink into the fabric of the shirt.  The
better screen printers use less pressure and control the amount of ink deposited
by mesh count, stencil thickness, squeegee angle and speed rather than simply
pressure.

 To duplicate the advantage of an automatic press, I recommend manual
printers lock their wrists, noting the squeegee angle, and then stepping back
to print rather than moving their arms back.  A cheap plastic protractor
as used in school can be used to measure the squeegee angle.

 Converting the variables of printing to constant, numerical values gives
the screen printer the tools required to print both ringspun and open-end yarn.

A simple, snap decision to select ringspun or open-end yarn over the other ignores many
other decision criteria that may weigh heavily in the balance.  In some
cases, certainly, the screen printer does not even have a choice, because the
customer has selected the garment.  Then the printed results depend on
the materials and methods used.