The ferrotype and how to make it - The Grian Press

FOG. 119
black spots on the plate when developed. When
these occur, the remedy suggests itself: clean the
Collodion bottle, and remove all the dust from
the shelves where the plates stand.
Comets are particles of dust which fall upon
the surface of a coated plate, or are received from
the bath, on the ])late being dipped. These spots
of dust or dirt adhere to the surface of the Collo-
dion, and when the developing solution is applied,
they form neuclei for heavier deposits of silver,
little tails of silver forming in the direction of
the flow. Remedy : filter the bath, and keep
always covered, and keep the dark room free
from dust.
The silver bath receives from each plate that
is immersed a portion of its iodide. After the
bath becomes saturated, and can take up no
more, this iodide forms itself into innumerable
particles or crystals of iodo-nitrate of silver, com-
monly called "free iodide." This free iodide
deposits itself on the surface of the plate, pro-
ducing (on the negative) what is called " pin-
holes," and in the ferrotype the whole surface is
covered with tiny black spots. For remedy,
see article on silver. If not convenient to
change the bath at once, reverse the dipper and
turn the Collodion surface of the plate down-
ward.
Perpendicular streaks are caused most gener-
ally by the bath being either too strong or too
weak for the Collodion. An old and sh'ghtly de-