What can you do to prevent fading on printed self adhesive
(sticky) labels when exposed to sunlight?
by Dr Adrian Steele
Published on this site: April 7th, 2006 - See
more articles from this month
What can you do to prevent fading on printed self adhesive
(sticky) labels when exposed to sunlight?
This article describes a the problems of fading print when
different types of printed self adhesive labels are exposed
to sunlight. This is a common problem for industrial users
of self adhesive labels who want their labels to be used outside,
in near constant exposure to the potentially harmful UV rays
in sunlight.
Dr Adrian Steele of Mercian Labels, a specialist in self
adhesive labels has been looking into this problem. Labeling
specialists
are frequently approached by clients with queries about the
potential effects of sunlight on print labels. This is most
often a result of the degrading effects of UV light in sunlight
when exposed to labels used outside or on view from the outside.
The "bleaching" or fading effects of sunlight are
commonly accepted as occurring on many coloured surfaces.
The purpose of the interesting experiment they are currently
undertaking was to examine the effects of sunlight on printed
labels, manufactured using the following printing techniques:
- flexography - solvent based ink - dye based
- flexography - water based ink - pigmented
- letterpress - UV cured ink
- hotfoil - heat and pressure cured ink
- thermal transfer - wax resin based foil image
The experiment commenced in early 2006 and it is planned
to record the results throughout the year. The experiment
is only resigned to test the effect of UV light on the printed.
The method they used was to select some recently printed self
adhesive labels manufactured early in 2006. These labels were
stuck onto 7 A4 sheets of paper, along with a tick box description
of the printing method and any varnish or lamination.
The abbreviations used are as follows:
- HF - hotfoil printed
- FW - flexo printed with a water based pigment ink
- FS - flexo printed with a solvent based dye ink
- LPUV - letterpress printed with a UV curable ink
- TT - thermal transfer printed with a wax resin ribbon
- LAMI - laminated with a 23 micron clear polyester overlamination
- VARN - varnished with a UV cured clear gloss varnish
The sheets were then cut in half, with half the label on
each part of the sheet. The left half of all 7 sheets were
labeled as "Exposed to UV" and permanently displayed
in window fully exposed to sunlight. The right half of all
7 sheets were labeled as "Not Exposed to UV" and
stored in a draw away from all forms of light.
At approximately 2 week intervals the exposed halves were
removed from the window and photographed by a digital camera
in indoor light conditions adjacent to their unexposed counterpart.
The purpose of this was to allow a direct comparison with
an undamaged version of the label over time.
The same digital camera and lighting conditions were used
throughout, and
the images were not manipulated in any way apart from cropping
and rotating using basic image manipulation software.
The results can be seen on their webpage that describes
the experiment:
An experiment on the effects of UV (ultraviolet) daylight
from the sun on self adhesive labels printed by hotfoil, letterpress,
flexography and thermal transfer, including laminated and
non laminated labels by Mercian Labels (UK) using comparative
photography
Initial conclusions were that most images were very stable,
but one form of printing (solvent dye based flexo inks) exhibited
notable colour changes relative to the others.
Dr Adrian Steele PhD is a leading specialist in
self adhesive labels at Mercian Labels Ltd (UK) - www.selfadhesivelabels.com and www.securitylabels.com
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