Impressions - March 2016 - 56

HYBRID

REMOVING EMULSION
Hybrid

An important part of screen cleaning is

Hybrid

removing emulsion. To do this, emulsion
removers, also known as strippers, are
available on the market and vary greatly
in price.

SBQ

SBQ

You can buy emulsion removers that
are ready for use (RFU) for a relatively

Resin

Diazo
Diazo

low per-gallon price. You also can buy
granular solids that need to be dissolved
or liquids that need diluting. The solids

SBQ Emulsion

Diazo Sensitizer

SBQ-Dual Cure Emulsion

Diazo Sensitizer

are more expensive, but you can make
gallons of product. This type also gives
you control over the concentration.
When you use the right chemicals and
follow the instructions, you typically
won't have problems with hazing or
ghosting. These are stains that remain
in your screen after you finish cleaning
it. If you still can see part of the image
on your screen after cleaning, you have
used the wrong chemicals. This problem
typically occurs when mineral spirits are
used because they lock stains in. Any
petroleum-based product will burn the
image into the mesh.
Haze remover is designed to remove
persistent stains, but you shouldn't use
it because, similar to toilet bowl or pool
cleaner, it is very caustic. It works by
eating off the surface of the mesh. Once
you have used a haze remover, the mesh
becomes reduced in diameter and,
therefore, brittle. Thus, it will no longer
allow you to achieve and maintain optimal tension. This forces you to print with
a low-tension screen, which can create
an array of problems.
- Impressions archives

P.56

come in single-cure and dualcure formulations.
The primary difference between
single- and dual-cure emulsions
is that the former has one curable
component and the latter has two.
Both diazo- and SBQ-sensitized
emulsions come in single-cure or
dual-cure formulations.
Dual cures (both diazo and SBQ)
contain UV-curable resin and
single cures (both diazo and SBQ)
do not. Dual cures are capable
of dual resistance (solvent and
water) but it is not a given,
while single cures are not. It's
important to note that single
cures offer single resistance to
either solvent or water, but not
both. The pictograms use an icon of
the sun to represent each curable
component (diazo, SBQ, UV-curable
resin) contained within each type
of emulsion.
Many
T-shirt
printers
traditionally have used singlecure emulsions but now are using
inks that may require both water
and solvent resistance, something
single-cure emulsions do not
necessarily do well. Co-solvent
water-based inks (like many of
the new HS-As) require not only
water resistance, but also solvent
resistance from their emulsion.
Also, some plasticizers used in
new eco-friendly plastisol inks
require greater solvent resistance
than that which currently
is provided by some singlecure emulsions.
Currently, emulsion preferences
are trending toward SBQ dual cures.
Since they don't use diazo, they

I M P R E S S I O N S M A G . C O M MARCH 2016

are faster exposing than diazo
dual cures and, thus, are better
equipped to handle the demand
for faster throughput required
by busy shops and those investing
in CTS equipment with integrated
LED exposure systems. Compared
to single-cure SBQs, dual-cure
SBQs typically have better copying
properties (resolution, mesh
bridging and edge definition) and
solvent resistance.
There's some confusion about
the term "hybrid," as it relates
to describing some (but not all)
SBQ dual cures. If UV-curable
resin is the defining trait of
a hybrid emulsion, then diazo
dual cures - which also contain
UV-curable resin - also must be
considered hybrids.
A hybrid results from the
combination of two different
elements, which more accurately
describes what occurs when diazo
is added to either SBQ or SBQ dualcure emulsion. Adding diazo to
SBQ emulsions means essentially
combining two different emulsion
varieties (diazo and SBQ), which
together better fits the hybrid
definition and should be easier
to understand.
When selecting an emulsion
for your facility, it always is
important to do your homework to
ensure the emulsion you select
will yield favorable results with
your current exposure system and
meet the demands of the ink system
you currently have in place or
intend to add.
Most single-cure emulsions
used by textile printers are
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Impressions - March 2016

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