Getting Started Screen Printing

Start Printing

Most people starting out spend too much money.  If you are new to screen
printing, the risk is you will buy what you do not need or more than you need.

Local businesses and schools usually do not request more than two colors.  They may not
have the need or want to pay for more colors.

The orders requiring more colors or lots of shirts, or items that would be
a new printing problem can be sub-contracted to another screen printer.  That
allows a person with limited funds to start a business without spending a lot
of money on capability that will seldom be used.

The dryer can be a flash dryer rather than a faster conveyor.  An exposure
unit can be made at home for under $50 to avoid spending $1200 and more.  People
starting out do not need a lot of money to offer excellent quality to customers.

The starting point for a new business is a realistic assessment of who the
customers will be, and what they will need.  Keep it simple.  Planning
to print T-shirts and one other item at first, like tote bags, will make starting
a new business a more pleasurable, productive and profitable experience.  Too
many different items to print can create too many problems for an inexperienced
screen printer.

Training  Before spending any money, get training.  Screen
printing involves many cross roads at which you will make decisions.  Will
you go in the right direction?  For example, there are several types of
wooden screens, welded aluminum and retensionable screens.  There are
diazo, dual cure and photopolymer liquid emulsions and capillary films.  That
is just the beginning to the number of choices, and each requires training.

People starting out typically select the lowest purchase cost, and do not
consider the ownership costs.  If one screen costs $16 and another $35,
but the $16 will produce some misprinted shirts, slower production and aching
wrists, is the $16 screen the better buy?  Most people never ask the right
questions.

Training is available from many sources.  There are books, schools, seminars
at trade shows, trade magazines, audio and video tapes, and people who will
help you.  You might even take a job working for another screen printer
before starting out on your own.  During this process the choices of products
and technology should be itemized and evaluated.  The risk is, being new,
you might not know the right questions to ask.  What might seem like the
best option might not be the best option. Mistakes can be costly, and may ultimately
require investment a second time in a type of product that has already been
purchased.

To a large extent, a person new in business relies on what sales personnel
and screen printers suggest.  To make sure you are taking advice from
a major league player and not a career minor leaguer, the work of the mentor
should be inspected and critiqued.  There are lots of sales people who
have never printed.

 Many screen printers have not taken the time and spent the money to
itemize and evaluate the choices.  When offered a “satisfied customer” list,
consider the source.  Anyone can produce such a list.  Even cold
calling screen printers in the Yellow Pages does not establish whether the
person answering the phone is a major league player.

 You need to see the advisor in action to know if you have the best source
of information.  Trade shows, shop visits and published accomplishments
are good ways to evaluate the person whose advice you will be relying upon.  Their
advice is a form of training.

Training reduces risks.  Unfortunately most people start out without
any training.  Too many get frustrated and give up on their dream of having
their own business.

Press Selection  Most people starting out think more colors are
better.  Actually, more colors on a manual press result in lower productivity.

For each one foot increase in the diameter of a press, the person printing
will have to push the screens around in a circle an extra 3.14 feet per shirt.  That
is because the circumference of a circle is measured as diameter times Pi (3.14).  Selecting
a 6-color press with  an 8’ diameter rather than a 4-color with
a 3’ diameter adds 5’ x 3.14 or 15.7’ of movement per shirt,
or 1570’ for 100 shirts.

That machine will be the foundation to the print.  The foundation needs
to be rock solid.  If the platen or color arm in the registration gate
move during printing, printed images may be out-of-registration.  Push
down on the platen with the force used when printing.  Does the platen
deflect at all?  If it does, find another that does not deflect.

When the color arm is in the registration gate without a screen, an attempt
should be made to move the arm laterally and to twist the arm.  There
will be zero movement of platens and color arms on the best presses.  Larger
diameter presses are more difficult to design without deflection, because the
force you apply is being leveraged over a longer distance.

People often ask about the difference between a press with one platen versus
four or six platens that rotate independently from the screens.  If your
business will involve a lot of flash curing, the rotary press will be more
efficient.  A rotary press or platen is sometimes referred to as a speed
table.  A press with a speed table requires more space and costs more
money than a press without this feature.  The question, then, is whether
or not a flash is necessary.

A lot of flashing may be unnecessary.  For example, if screens are very
tight, a lot of printing can be wet-on-wet.  That means successive colors
are printed without flash curing.  The color of the garment, mesh count,
type of ink and choice of liquid versus capillary film bear on the answer whether
flash curing will be necessary.

There are all those cross roads in the decision making process again.  If
the customers are businesses and schools requiring typically two color images
rather than retail store customers who want 6 colors, the cost of a speed table
can be avoided.  The cost of lower productivity from flash curing on a
few jobs may be better than a larger, less productive, press on all jobs.

Micro registration is a key feature to be considered.  The image in
the screen is exposed from a “positive.”  A positive is a
black image on clear or transparent medium like vellum. The positive is taped
to the platen and the screen is moved until its image matches the positive
from which the screen was made, exactly.  When tightening the screen in
the press, often the screen will move slightly, especially if the screen is
over tightened.

Rather than loosen the screen, the micro is unlocked and micrometer-like fine
adjustments can be made.  That is micro registration – in theory.  In
practice, a micro may move a screen over a curved line or along a straight
line.  A curved line is almost impossible to work with, but the more common
situation, particularly if you buy an older, used press.  This is a feature
to see demonstrated, but only an issue if printing a lot of jobs more than
two colors where the colors are butt registered or four color process.

There are many other features in a press to examine.  What is the range
in size and weight of screens the press can accommodate without screens flying
up or falling down?  What attachments are available to expand revenue?  How
fast can an attachment be changed?  Are there knobs or press structure
for wet shirts to catch on and smear when the shirt is being removed?  Doing
your home work is important to getting the most value for your investment.

Dryer  Flash dryers cost less and take less space than a conveyor,
and can be used for a full cure.  A flash cure is typically 6-8 seconds
whereas a full cure is 60 seconds.

A flash cure prevents the ink from picking up under subsequent screens during
the printing process, but does not cure ink sufficiently for ink to survive
repeated washings.   Sometimes flashing is necessary.  Dark
shirts with a very soft feel, or “hand,” often have been printed
with a very thin coat of white ink, known as an underbase, flash cured, and
then over-printed with the same or different color.  Materials that do
not absorb ink like nylon jackets must be flashed before printing the first
color and between each color so shrinkage occurs before printing and inks are
not smeared by subsequent screens.

The problems with using a flash unit for a full cure are low productivity
and stress you suffer worrying about the cure.  At best you can fully
cure 30-40 shirts per hour with a flash unit compared to 100-150 and more with
a conveyor dryer.  A conveyor runs at a constant speed and temperature  giving
a consistent result.  The stress that comes with a flash unit is the concern
too short of a cure time will create unhappy customers when the ink washes
out.  Too long of a flash will scorch the shirt.  The margin between
too short and too long is very  thin.  Monitoring the cure time while
trying to load and print other shirts creates stress.  The solution is
slow curing and low productivity. 

When selecting a flash or conveyor, look first for a temperature control.  A
household iron has temperature control to regulate heat for 100% cotton versus
synthetics.  Heat control is a must, but many dryers do not include this
requirement.

Check flash dryers to see if they are top heavy and subject to tipping over
with an element at 350 degrees.  Check for legs that stick out for someone
to trip into the hot element rather than a stand positioned out of the way.  The
element must be absolutely parallel to the platen for puff inks to puff evenly.  You
might want casters on a flash unit for your convenience.

A flash unit in smaller shops will be 110 volts so it can be plugged into
any electrical outlet.  Outlets are designed for a maximum of 15 amps.  Some
flash units will draw 19 amps.  Excessive amps in a circuit can cause
a house fire.  A plug with two parallel bars is designed for a maximum
of 15 amps whereas one bar perpendicular to the other bar is designed for 20
amps.

Heat for curing comes from wattage.  Watts are volts times amps.  A
220 volt unit will produce the same wattage as a 110 volt unit that draws twice
as many amps.  A new shop can buy more curing capability by specifying
220 volts.  The circuits, switches, etc., in the dryer will last longer
with lower amps and higher voltage like 220, 230 or 240 volts.  Gas as
a replacement for electricity only makes economic sense in larger dryers.

Flash dryers and conveyors without vents bake the ink whereas conveyors with
vents have substantial convection.  A conveyor without a vent, or which
has a covered vent, runs much hotter, because less heat escapes.  That
is acceptable on a lot of jobs, but dark shirts being cured in a conveyor can
create an odor you won’t want to smell all day.  The choices will
be a vented dryer, or open the windows and doors.

You never want to find lint on shop surfaces, because that means you are breathing
lint which gets lodged in your sinuses.  Adequate draft in a vent makes
a dryer less efficient, but the work environment healthier.  Lint in sinuses
causes headaches.  I learned this when I was unable to work for five weeks
after printing 100% cotton shirts two consecutive nights in a 25,000 sq. foot
room without venting.

Screens  Every screen printer with 20 minutes or more experience
pulling a squeegee agrees tighter screens are better.  When a screen is
tight one color is less likely to bleed into another color.  Half tones
will be reproduced more accurately rather than be dragged across the shirt.  Ink
can be cut easier and more cleanly.  There will be less chance of ink
build up under a screen and more chance of a brighter, softer image in the
garment.

All mesh relaxes.  Higher mesh counts like a 230 or 305 threads per linear
inch composed of 35 micron diameter threads will lose 25% of its tension within
two hours of being tensioned close to its breaking point.  Lower mesh
counts lose tension more slowly.  Often screen printers receive what they
think are tight screens which they recognize as being softer at the end of
the first print run of 100 shirts or more.

The solution is to retension mesh after two hours, then four hours, and the
next day before using the screen on the first job.  When the job is over,
remove the ink and stencil, and retension after each job until 500 prints have
been accumulated on the mesh.  At about this point, the mesh becomes
work hardened, and will not need further retensionings.  Jobs will be
easier and faster to set up, but more importantly, image quality will be far
superior.

At a trade show, observe what kind of screens the press manufacturers are
using, and their image quality.  Find out what the large contract printers
use.  Then find out if your advisor is major or minor league by the screen
recommended.

Emulsion   Liquid emulsion should be applied with a scoop
coater devoid of any nicks.  The angle, speed and pressure applied during
the coating process affect the stencil thickness.  Other variables to
stencil thickness are the number of times the scoop coater is drawn up each
side of the screen, air temperature and humidity.  Capillary film avoids
all these variables as long as the person coating the screen does not squeegee
the wet, soft stencil material into the mesh.

Capillary film is fundamentally different from liquid emulsion.  With
film, the ink passes around the threads of the mesh and the image is created
by pure stencil material.  The image resolution will be better when the
mesh is not in the stencil influencing how the image is created.  That
is another reason not to squeegee wet capillary film into mesh.  The film
thickness controls the thickness of the ink deposit and therefore color.  With
liquid emulsion, the mesh count meters the amount of ink passing through to
the shirt.

Capillary film avoids production losses from pin holes and provides other
benefits, but most of the screen printers (the people you might ask for advice
and training) use liquid rather than capillary film.  Most of these folks
have not itemized and evaluated the choices in emulsion versus capillary film,
or did so before the newer, better formulas were developed.  Liquid emulsion
is fine for start up shops for non-critical work, short run jobs with large
images in multiple colors, and when you have time to fix pin holes in screens.

Ink  The ink companies all know each other’s prices.  When
you realize that you can print say 300-1000 shirts per quart, a dollar or two
difference works out to $ .006 - $ .002 difference in cost per shirt.  Performance
is the issue, not price.

Inks are the most difficult part of the screen printing process to understand.  The
ink companies worry about how their colors match to independent standards so
your image meets your customer’s requirements.  Suppliers talk about
viscosity which is a statement about flow.  An ink most screen printers
favor is viewed as creamy.

Too much  flow can result in dot gain.  That is ink that spreads
out on the garment.  The ink deposit might get thinner losing color strength
or sink into the garment allowing the color of the garment to influence our
recognition of color.

Inks should be stirred well before being removed from the container.  When
stirring, pull the stir stick straight out of the container.  Does the
ink drop off like yogurt would, or remain attached to the ink in the container
like a string when the stick is 6” above the container?  Now we
are talking about shear.  Shear is seldom mentioned by suppliers, but
is a critical performance characteristic to image resolution, color strength
and the feel of the printed image.

Conclusion  Starting a screen printing business means confronting
the cross roads to your success over and over again.  Your largest investment
will be your time and wisdom to select the right advisors.

 I am always amazed at trade shows and on telephone calls when people
only ask price.  Only twice in 22 years have I been asked the right question.  Ask
why you should buy a product and not other products.  Ask why you should
buy from the sales person and not the competitors.  Find out how the
competitors answer the same question.  Then find independent evidence
of who was right.

That will put you on the right road to success.