<s>
A	O
heliographic	B-Application
copier	I-Application
or	O
heliographic	O
duplicator	O
is	O
an	O
apparatus	O
used	O
in	O
the	O
world	O
of	O
reprography	O
for	O
making	O
contact	O
prints	O
on	O
paper	O
from	O
original	O
drawings	O
made	O
with	O
that	O
purpose	O
on	O
tracing	O
paper	O
,	O
parchment	O
paper	O
or	O
any	O
other	O
transparent	O
or	O
translucent	O
material	O
using	O
different	O
procedures	O
.	O
</s>
<s>
In	O
general	O
terms	O
some	O
type	O
of	O
heliographic	B-Application
copier	I-Application
is	O
used	O
for	O
making	O
:	O
Hectographic	O
prints	O
,	O
Ferrogallic	O
prints	O
,	O
Gel-lithographs	O
or	O
Silver	O
halide	O
prints	O
.	O
</s>
<s>
All	O
of	O
them	O
,	O
until	O
a	O
certain	O
size	O
,	O
can	O
be	O
achieved	O
using	O
a	O
contact	B-Application
printer	I-Application
with	O
an	O
appropriate	O
lamp	O
(	O
ultraviolet	B-Application
,	O
etc	O
...	O
)	O
but	O
for	O
big	O
engineering	O
and	O
architectural	O
plans	O
,	O
the	O
heliographic	B-Application
copiers	I-Application
used	O
with	O
the	O
cyanotype	O
and	O
the	O
diazotype	B-Application
technologies	O
,	O
are	O
of	O
the	O
roller	O
type	O
,	O
which	O
makes	O
them	O
completely	O
different	O
from	O
contact	B-Application
printers	I-Application
.	O
</s>
<s>
In	O
the	O
"	O
argot	O
"	O
of	O
engineers	O
,	O
architects	B-Application
and	O
designers	O
,	O
the	O
resulting	O
plan	O
copies	O
coming	O
from	O
any	O
type	O
of	O
heliographic	B-Application
copier	I-Application
no	O
matter	O
they	O
were	O
either	O
blue	O
or	O
white	O
,	O
were	O
traditionally	O
called	O
blueprints	B-Application
,	O
name	O
derived	O
from	O
the	O
blue	O
background	O
color	O
of	O
the	O
cyanotype	O
technique	O
,	O
which	O
was	O
the	O
previous	O
process	O
for	O
obtaining	O
blueprints	B-Application
,	O
When	O
the	O
diazo	B-Application
based	O
compounds	O
changed	O
the	O
background	O
color	O
to	O
white	O
,	O
in	O
technical	O
environments	O
,	O
-by	O
tradition-	O
,	O
the	O
name	O
for	O
copies	O
of	O
technical	O
drawings	O
remained	O
Blueprint	B-Application
,	O
although	O
in	O
English-speaking	O
countries	O
,	O
it	O
was	O
intended	O
,	O
without	O
much	O
success	O
,	O
to	O
change	O
the	O
name	O
from	O
Blueprint	B-Application
to	O
Whiteprint	B-Application
.	O
</s>
<s>
Depending	O
on	O
the	O
color	O
or	O
the	O
line	O
and	O
background	O
,	O
the	O
appropriate	O
paper	O
may	O
be	O
developed	O
for	O
blueprints	B-Application
(	O
blue	O
background	O
)	O
,	O
whiteprints	B-Application
(	O
blue	O
line	O
and	O
white	O
background	O
)	O
,	O
black	O
line	O
(	O
white	O
background	O
)	O
and	O
sepia	O
,	O
using	O
the	O
same	O
machine	O
and	O
process	O
.	O
</s>
<s>
Using	O
the	O
right	O
compound	O
some	O
"	O
cyano	O
copiers	O
"	O
could	O
be	O
adapted	O
to	O
be	O
used	O
as	O
"	O
diazo	B-Application
copiers	I-Application
"	O
.	O
</s>
<s>
When	O
Herschel	O
developed	O
the	O
process	O
,	O
he	O
considered	O
it	O
mainly	O
as	O
a	O
means	O
of	O
reproducing	O
notes	O
and	O
diagrams	O
,	O
as	O
its	O
use	O
in	O
blueprints	B-Application
.	O
</s>
<s>
Engineers	O
and	O
architects	B-Application
used	O
to	O
draw	O
their	O
designs	O
on	O
cartridge	O
paper	O
;	O
these	O
were	O
then	O
traced	O
by	O
hand	O
on	O
to	O
tracing	O
paper	O
using	O
Indian	O
ink	O
,	O
which	O
were	O
kept	O
to	O
be	O
reproduced	O
with	O
the	O
cyano-copier	O
whenever	O
they	O
were	O
needed	O
.	O
</s>
<s>
Introduction	O
of	O
the	O
blueprint	B-Application
process	O
eliminated	O
the	O
high	O
expenses	O
of	O
photolithographic	O
reproduction	O
or	O
of	O
hand-tracing	O
of	O
original	O
drawings	O
.	O
</s>
<s>
By	O
the	O
latter	O
1890s	O
in	O
American	O
architectural	O
offices	O
,	O
a	O
blueprint	B-Application
was	O
one-tenth	O
the	O
cost	O
of	O
a	O
hand-traced	O
reproduction	O
.	O
</s>
<s>
The	O
blueprint	B-Application
process	O
is	O
still	O
used	O
for	O
special	O
artistic	O
and	O
photographic	O
effects	O
,	O
on	O
paper	O
and	O
fabrics	O
.	O
</s>
<s>
Different	O
blueprint	B-Application
processes	O
based	O
on	O
photosensitive	O
ferric	O
compounds	O
have	O
been	O
used	O
.	O
</s>
<s>
The	O
process	O
of	O
diazotype	B-Application
(	O
Whiteprints	B-Application
)	O
replaced	O
the	O
cyanotype	O
process	O
(	O
blueprints	B-Application
)	O
for	O
reproducing	O
architectural	O
and	O
engineering	B-Architecture
drawings	I-Architecture
because	O
the	O
process	O
was	O
simpler	O
and	O
involved	O
fewer	O
toxic	O
chemicals	O
.	O
</s>
<s>
The	O
different	O
names	O
blue-line	O
copier	O
,	O
whiteprint	B-Application
copier	I-Application
or	O
diazo	B-Application
copier	I-Application
,	O
were	O
given	O
,	O
due	O
to	O
the	O
nature	O
of	O
the	O
process	O
,	O
which	O
consists	O
in	O
exposing	O
to	O
an	O
ultraviolet	B-Application
light	I-Application
a	O
previously	O
sensitized	O
paper	O
with	O
a	O
component	O
called	O
diazo	B-Application
,	O
and	O
finally	O
developing	O
it	O
in	O
a	O
bath	O
(	O
a	O
solution	O
of	O
ammonia	O
in	O
water	O
)	O
which	O
converts	O
the	O
parts	O
not	O
exposed	O
to	O
light	O
,	O
to	O
a	O
dark	O
blue	O
colour	O
(	O
blue-line	O
)	O
over	O
an	O
almost	O
white	O
background	O
.	O
</s>
<s>
A	O
little	O
smell	O
of	O
ammonia	O
and	O
a	O
faintly	O
purplish	O
paper	O
colour	O
are	O
the	O
main	O
characteristics	O
of	O
a	O
whiteprint	B-Application
.	O
</s>
<s>
The	O
diazo	B-Application
copies	I-Application
are	O
of	O
different	O
sizes	O
and	O
for	O
this	O
reason	O
the	O
diazo	B-Application
paper	I-Application
is	O
obtainable	O
in	O
standard	O
sizes	O
that	O
vary	O
from	O
30cm	O
to	O
60cm	O
wide	O
,	O
after	O
de	O
process	O
the	O
copied	O
paper	O
can	O
be	O
cut	O
to	O
the	O
desired	O
size	O
.	O
</s>
<s>
The	O
paper	O
used	O
for	O
the	O
diazo	B-Application
copies	I-Application
is	O
usually	O
a	O
bond	O
paper	O
or	O
similar	O
type	O
,	O
with	O
a	O
diazo	B-Application
coating	O
sensitive	O
to	O
the	O
UV	B-Application
light	O
.	O
</s>
<s>
The	O
original	O
plan	O
and	O
the	O
sensitized	O
paper	O
,	O
are	O
introduced	O
,	O
in	O
perfect	O
contact	O
,	O
within	O
the	O
copier	O
rollers	O
that	O
pull	O
and	O
expose	O
them	O
to	O
a	O
source	O
of	O
ultraviolet	B-Application
light	I-Application
,	O
typically	O
a	O
blacklight	B-Application
lamp	O
,	O
similar	O
to	O
the	O
manual	O
action	O
to	O
expose	O
both	O
sheets	O
strongly	O
bonded	O
directly	O
to	O
the	O
sunlight	O
,	O
and	O
once	O
exposed	O
:	O
</s>
<s>
In	O
the	O
diazo	B-Application
copier	I-Application
,	O
the	O
paper	O
is	O
immersed	O
in	O
a	O
developer	O
solution	O
made	O
from	O
ammonia	O
(	O
or	O
ammonia	O
vapor	O
)	O
converting	O
the	O
parts	O
of	O
the	O
paper	O
not	O
exposed	O
to	O
the	O
light	O
source	O
to	O
a	O
characteristic	O
dark	O
blue	O
colour	O
.	O
</s>
