433 OF ENGINEERING FORMULÆ,
Fekeotype (or Blue) Process.
By this process prints are produced in prussian blue and
white, a print taken direct from an ordinary tracing in indian
ink giving white lines on a blue ground.
SENSITIZING SOLUTION.
. f Citrate of iron and ammonia .. .. 100 grains.
( Water................................. 1 ounce.
g f Red prussiate of potash .............. 70 grains.
(Water .. .. ................ 1 ounce.
These solutions will keep indefinitely before mixing, but,
when mixed, they should be used at once or left in the dark.
PREPARING THE PAPER.
Mix equal quantities of A and B and apply to one side of
the paper with a sponge. The sponge should be as full as it
will hold of the solution, which should be liberally applied to
the paper for about two minutes. Then squeeze out the
sponge and wipe off all the solution from the surface of the
paper, care being taken to use tbe sponge lightly without
abrading the surface. The paper, which is now of a bright
yellow colour on the prepared side, should be hung up to dry
in the dark.
PRINTING.
The printing is done in every respect in the same manner
as for ordinary photographic silver prints, the tracing repre-
senting the negative.
Behind the glass of the printing frame lay the tracing, face
next the glass, behind the tracing the prepared paper, prepared
surface next the tracing. Put out in the sun or diffused day-
light until sufficiently printed.
In bright sun-light from 9 a.m. to noon the time required
will be from 8 to 10 minutes. In the afternoon a somewhat
longer exposure must be given.
1’IXIKG.
The print is fixed by simply washing thoroughly In clean
water.
ADDITIONS AND ERASURES,
A white line may be taken out by going aver it with a quill
pen or brush dipped in the sensitizing solution, exposing to
the nun, and washing as before. Additions or corrections in
white may be made with a quill pen dipped in a solution of
40 grains of carbonate of potash to 1 ounce of water. After
using this solution, the potash must be dried with blotting
paper and washed, or the lines will spread and become blurred.
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