A number of factors can
cause puckering and tunneling of a premask or application tape laminated on
a screen printed vinyl graphic. These factors fall into three broad categories:
environment, material processing and product selection.
Controlling your plant
environment and your processing are certainly important. High humidity causes
many tunneling and puckering issues. When
the humidity is high, the paper tape absorbs the moisture and it grows, resulting
in the tape pulling away from the printed vinyl. Problems can also occur when a
plant changes from air conditioning to a heating cycle.
While humidity is a common problem
during the summer months, temperature is frequently a factor in the winter. When
temperatures in a plant are colder, the adhesive on the premask become stiffer
and does not flow out so readily over the surface of the decal as when plant
temperatures are warmer. Without proper adhesive flow out, the tape may not stick
adequately.
Processing is also critical.
Before the screen printed decal is premasked, the ink must be thoroughly cured.
Inadequate curing may cause the premask to release from the print. Or in
storage, the bond between the tape and print can grow unacceptably. Neither
situation is desirable.
In screen printing, laminating is the recommended method
for applying a premask to a print. Too much unwind tension in the laminating
process, however, will stretch the paper inducing mechanical stresses in the
tape. As the stretched tape returns to its original state, the graphic can curl
as well as pucker from the print.
If you are have an issue with puckering
or tunneling, application of a little heat (100⁰F
or 38⁰C) when laminating the tape to the graphic can cause
the adhesive on the application tape to flow out better and create a better
bond to the graphic. Of course, you must have a laminator with a heated roller.
The most important factor,
though, is material selection – selecting the right tape for the application. In
some cases, a standard weight paper application tape will work as a premask for
printed decals…sometimes but, not always. Standard paper application tapes are
formulated for sign shop applications, not for screen printing.
RTape has developed a series
of premasks designed specifically for screen printed graphics. These premasks
utilize a heavier, more stable paper facemask with a high concentration of
latex saturant. Because heavyweight papers have more saturant, the tape absorbs
less moisture, even when humidity is high. Standard weight paper tapes have a
lower saturant concentration. When the humidity is high, the paper absorbs
moisture and the paper grows.
For screen print applications, RTape has developed a series of heavyweight paper premasks.
Screen print premasks also have
a heavier coat weight of adhesive. This is important for any screen printer
printing with UV inks. UV inks are 100% solids. What that means is that 100% of
what you print on the substrate stays on the substrate. This heavy deposit of
ink creates a textured surface. To adhere to the print, the premask adhesive
must flow into the valleys of the texture. If it doesn’t, the tape will pucker.
The hand of the paper used
in making the premask is also critical. Some papers have a softer hand than others.
“Hand” describes the suppleness of the sheet. Paper with a harder hand is not
sufficiently malleable to flow with the texture of the print. Stiffer sheets
are prone to tunneling and puckering.
The final factor affecting
the performance of a screen print premask is the concentration of RLA® additive
in the adhesive. RTape’s 4760RLA and
4775RLA are two premasks which will adhere well to smooth release liners.
Pressure sensitive embossed release liners, by comparison, are challenging. For
these type of films, RTape recommends use of it 4761RLA, which features a much
higher concentration of RLA® additive.
4760 – Premask
for UV Inks and Clear Coats. (Use on square cut printed panels
with no exposed release liner.)
4760RLA – Premask/Prespacing Tape for Printed or
Unprinted Decals. (Use on cut-to-shape large format
graphics with exposed, smooth release liners.)
4761RLA –
Prespacing Tape for Air Egress Vinyls. (Use on cut-to-shape
large format graphics with exposed, embossed air egress release liners.)
4775RLA –
Prespacing Tape for Small & Medium Size Die Cuts. (Use
on small to medium cut-to-shape graphics with exposed, smooth release liners.)
Related Stories
Vinyl Application Videos
Squeegee Technique. Nothing is more basic in vinyl application than the squeegee. But some squeegees work better than others. And there are right ways and wrong ways to use this simple tool. This video clip reviews squeegee selection, squeegee care and squeegee technique. Click to Link
Wet Applications. Dry applications are typically recommended for most vinyl applications. For those exceptions to the rule, this instructional video explains the right way to perform a wet application. Click to Link
Application of Window Graphics. Installing vinyl graphics on glass can be challenging, because the adhesive aggressively grabs onto this high energy surface. Repositioning graphics on window is generally difficult, if not impossible. This instructional video explains how to dry apply window graphics right the first time. It also describes the necessary steps required for surface preparation. Click to Link
Transferring Frosted Window Graphics Films. Because frosted window films are highly textured, transferring cut vinyl graphics can be problematic. This video provides direction in selection of the right application tape and how to apply these films quickly, easily and without problems. Click to Link
3-Step Surface Prep. This instructional video describes how to properly clean the surface of a vehicle before applying pressure sensitive vinyl graphics to a trailer or doing a full wrap of a car or van. This three step surface prep involves detergent washing, solvent cleaning and a final wipe down with IPA. Click to Link
Vinyl Application Over Rivets. Applying vinyl graphics on vehicle surfaces with rivets is challenging for most sign makers. Vinyl failures to these surfaces are all too common. This video demonstrates some tips and procedures, used by professional decal installers, which will make these demanding applications easier and more trouble-free. Click to Link
Vinyl Application to Corrugations. Learn how to apply vinyl graphics to corrugations in a relaxed state. Forcing films into the valleys of corrugations puts too much mechanical stress on the film. Sooner or later, the vinyl will lift or tent in valleys. Click to Link
Applying Air Egress Vinyls. Vinyl films with air egress release liners have almost eliminated bubbles and wrinkles from applied graphics. Air egress release liners with their highly textured surface structure are problematic. Not much will stick to these liners other than the vinyl film. At RTape our best premask solution for air egress liners is a special Conform® tape called 4761RLA. Click to Link
About Jim Hingst: After fourteen years as Business Development Manager at RTape, Jim Hingst retired. He was involved in many facets of the company’s business, including marketing, sales, product development and technical service.
Hingst began his career 42 years ago in the graphic arts field creating and producing advertising and promotional materials for a large test equipment manufacturer. Working for offset printers, large format screen printers, vinyl film manufacturers, and application tape companies, his experience included estimating, production planning, purchasing and production art, as well as sales and marketing. In his capacity as a salesman, Hingst was recognized with numerous sales achievement awards.
Drawing on his experience in production and as graphics installation subcontractor, Hingst provided the industry with practical advice, publishing more than 150 articles for publications, such as Signs Canada, SignCraft, Signs of the Times, Screen Printing, Sign and Digital Graphics and Sign Builder Illustrated. He also posted more than 325 stories on his blog (hingstssignpost.blogspot.com). In 2007 Hingst’s book, Vinyl Sign Techniques, was published. Vinyl Sign Techniques is available at sign supply distributors and at Amazon.
© 2016 Jim Hingst
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