<s>
Whiteprint	B-Application
describes	O
a	O
document	O
reproduction	O
produced	O
by	O
using	O
the	O
diazo	B-Application
chemical	O
process	O
.	O
</s>
<s>
Whiteprinting	O
replaced	O
the	O
blueprint	B-Application
process	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>
Two	O
components	O
underpin	O
diazo	B-Application
printing	O
:	O
</s>
<s>
The	O
resulting	O
coating	O
is	O
then	O
dried	O
yielding	O
the	O
specially	O
treated	O
paper	O
commercially	O
sold	O
as	O
Diazo	B-Application
paper	I-Application
.	O
</s>
<s>
Depending	O
on	O
the	O
thickness	O
and	O
type	O
of	O
the	O
master	O
,	O
the	O
intensity	O
of	O
the	O
UV	B-Application
exposure	O
light	O
is	O
adjusted	O
according	O
to	O
media	O
types	O
commonly	O
used	O
for	O
masters	O
in	O
any	O
particular	O
shop	O
.	O
</s>
<s>
The	O
original	O
document	O
is	O
laid	O
on	O
top	O
of	O
the	O
chemically-coated	O
side	O
of	O
a	O
sheet	O
of	O
diazo	B-Application
paper	I-Application
,	O
which	O
is	O
retrieved	O
from	O
a	O
light-protected	O
flat	O
file	O
,	O
and	O
the	O
two	O
sheets	O
are	O
fed	O
into	O
the	O
diazo	B-Application
duplicator	O
,	O
being	O
pulled	O
into	O
the	O
machine	O
by	O
rotating	O
rubber	O
friction	O
wheels	O
.	O
</s>
<s>
The	O
first	O
is	O
the	O
exposure	O
area	O
,	O
where	O
the	O
sandwich	O
of	O
the	O
two	O
sheets	O
(	O
the	O
master	O
and	O
the	O
diazo	B-Application
paper	I-Application
)	O
pass	O
in	O
front	O
of	O
an	O
ultraviolet	B-Application
lamp	O
.	O
</s>
<s>
Ultraviolet	B-Application
light	O
penetrates	O
the	O
original	O
and	O
neutralizes	O
the	O
light	O
sensitive	O
diazonium	O
salt	O
wherever	O
there	O
was	O
no	O
image	O
on	O
the	O
master	O
.	O
</s>
<s>
Once	O
this	O
process	O
is	O
complete	O
,	O
the	O
undeveloped	O
image	O
at	O
the	O
locations	O
where	O
the	O
UV	B-Application
light	O
could	O
not	O
penetrate	O
can	O
often	O
be	O
seen	O
as	O
very	O
light	O
yellow	O
or	O
white	O
marks/lines	O
on	O
the	O
diazo	B-Application
sheet	O
.	O
</s>
<s>
Next	O
,	O
the	O
original	O
is	O
peeled	O
from	O
the	O
diazo	B-Application
paper	I-Application
as	O
the	O
sandwich	O
of	O
master	O
and	O
diazo	B-Application
exits	O
the	O
machine	O
,	O
and	O
the	O
diazo	B-Application
sheet	O
alone	O
is	O
fed	O
into	O
the	O
developing	O
chamber	O
.	O
</s>
<s>
Many	O
blueprint	B-Application
shops	O
ran	O
ventilation	O
ducts	O
from	O
the	O
machines	O
to	O
outside	O
.	O
</s>
<s>
Smaller	O
and	O
mid-size	O
blueprint	B-Application
machines	O
were	O
often	O
outfitted	O
with	O
neutralizers	O
which	O
absorbed	O
some	O
of	O
the	O
ammonia	O
for	O
a	O
period	O
of	O
time	O
.	O
</s>
<s>
Sometimes	O
both	O
the	O
master	O
and	O
the	O
diazo	B-Application
print	O
are	O
inadvertently	O
fed	O
through	O
the	O
developing	O
chamber	O
together	O
.	O
</s>
<s>
If	O
this	O
occurs	O
,	O
one	O
simply	O
peels	O
the	O
master	O
from	O
the	O
diazo	B-Application
paper	I-Application
and	O
runs	O
the	O
diazo	B-Application
sheet	O
through	O
the	O
developer	O
once	O
more	O
to	O
more	O
fully	O
develop	O
the	O
lines	O
.	O
</s>
<s>
Diazo	B-Application
printing	O
was	O
one	O
of	O
the	O
most	O
economic	O
methods	O
to	O
reproduce	O
large	O
engineering	O
and	O
architectural	O
drawings	O
.	O
</s>
<s>
A	O
quirk	O
of	O
diazo	B-Application
blueline	O
prints	O
is	O
that	O
with	O
continued	O
exposure	O
to	O
ultraviolet	B-Application
light	O
,	O
either	O
from	O
natural	O
sunlight	O
or	O
from	O
typical	O
office	O
fluorescent	O
lighting	O
,	O
a	O
blueline	O
copy	O
can	O
fade	O
over	O
a	O
span	O
of	O
months	O
(	O
indoors	O
)	O
or	O
just	O
days	O
(	O
outdoors	O
)	O
,	O
becoming	O
illegible	O
.	O
</s>
