5.
EXPOSING
Very
importantly
before
exposing
‐
switch
on
the
exposure
unit
for
4
‐
5
minutes
to
ensure
that
the
tubes
are
warmed
up.
The
exposure
time
will
depend
upon
the
type
of
unit
you
have
and
also
which
dry
film
you
are
using.
As
a
guide,
if
you
are
using
one
of
our
4
or
6
tube
units,
exposure
time
will
be
45
‐
50
seconds
for
our
ferrous
dry
film
and
15
‐
20
seconds
for
our
non
‐
ferrous
dry
film.
However
to
be
completely
sure,
you
should
do
test
exposure
using
our
21
step
Stouffer
step
wedge
(Mega
part
Number:
500
‐
102).
This
is
done
by
placing
the
step
wedge
onto
a
laminated
plate
and
then
placing
a
piece
of
the
film
on
which
you
are
going
to
your
artwork
over
the
top
of
it.
Then
set
a
short
exposure
time
and
expose
the
plate
through
the
step
wedge
with
the
rest
of
the
plate
covered
by
a
piece
of
black
film,
so
that
it
is
not
exposed.
After
exposure
move
the
step
wedge
to
the
unexposed
area
and
cover
the
exposed
area
with
black
film
and
then
set
the
time
to
double
the
first
setting.
Then
remove
the
plate
and
develop
the
image.
This
will
show
you
if
you
are
in
the
correct
area
of
exposure.
What
you
are
looking
for
is
a
solid
7
to
8
with
a
clear
9
to
10.
You
may
have
to
repeat
this
process
a
few
times
to
get
the
correct
setting.
When
you
have
this,
set
the
required
time,
and
then
expose
the
dry
film
surface
through
your
artwork,
making
sure
that
the
ink
side
is
always
in
contact
with
the
dry
film.
6
.
Remove
the
exposed
plate
and
if
you
do
not
have
a
yellow
light
room,
place
it
in
a
bag
/
drawer
or
black
bag/
bin
liner
to
ensure
it
cannot
be
exposed.
Leave
the
plate
for
20
minutes
minimum
before
developing,
and
then
remove
the
top
protective
clear
film
and
plate
is
ready
to
be
developed.
NB:
Leaving
the
plate
for
1
hour
or
more
after
exposure
will
give
better
adhesion.
7.
DEVELOPING
Whether
you
develop
in
a
heated
tank
or
spray
system,
the
developer
should
be
at
28°C
–
32°C
Optimum
30°C.
Developer
should
have
a
pH
between
10.4
‐
11.4
when
mixed.
If
pH
goes
below
10.4
(minimum
10.2)
‐
change
developer.
Always
make
it
up
with
deionised
water.
In
order
to
achieve
the
correct
development
time,
you
need
to
establish
the
break
point.
This
is
the
point
where
the
resist
is
just
removed
down
to
the
metal
surface.
This
will
depend
on
the
type
of
dry
film
being
used
and
whether
the
developer
is
fresh
or
used.
After
this
break
point
time
has
been
established,
the
plate
should
be
left
in
the
developer
for
40%
of
the
time
taken
to
reach
this
point.
e.g.
time
to
reach
point
2
minutes,
then
total
time
in
developer
will
be
2
minutes
48
seconds.
Obviously
a
few
seconds
either
way
will
not
matter.
N.B:
If
you
are
using
a
static
tank
to
develop
the
image,
then
every
minute
you
need
to
move
the
board
up
and
down
a
few
times
to
create
some
agitation
of
the
liquid.
If
the
tank
has
bubbles
blowing
through
it
this
is
not
necessary.
As
a
rule,
tank
developing
will
take
4
‐
5
minutes
and
spray
developing
1
‐
2
minutes.
NB
:
If
developer
starts
to
foam
add
1ml
of
anti
‐
foam
per
5
litres
of
developer.
8
.
Remove
the
plate
from
the
developer
and
thoroughly
wash
under
running
water
preferably
using
a
soft
clean
sponge
to
wipe
over
the
surface
as
you
are
washing
the
plate.
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