PRINTING ON RESINIZED PAPER.
The following is taken from another volume of this series.[27]
To Mr. Henry Cooper we are indebted for a valuable printing process,
founded on substituting resins for albumen or other sizing matter. The
prints obtained by this process are very beautiful, and lack that gloss
of albumen which is often called vulgar and inartistic.
The following are the two formulæ which Mr. Cooper has communicated to
the writer:--
Frankincense 10 grains
Mastic 8 "
Calcium chloride 5 to 10 "
Alcohol 1 ounce
When the resins are dissolved in the alcohol, the paper is immersed in
the solution, then dried and rolled. The sensitizing bath recommended is
as follows (though the strong bath given at page 126 will answer):--
Silver nitrate 60 grains
Water 1 ounce
To the water is added as much gelatine as it will bear without
gelatinizing at 60° Fah.
The second formula gives very beautiful prints, soft and delicate in
gradation.
The paper is first coated with an emulsion of white lac in gelatine,
which is prepared as follows:--
3 ounces of _fresh_ white lac are dissolved in 1 pint of strong alcohol,
and after filtering or decanting, as much water is added as it will bear
without precipitating the lac; 1 ounce of good gelatine is soaked and
dissolved in the pint of boiling water, and the lac solution is added
with frequent stirring. If, at any stage of this operation, the gelatine
is precipitated, a little more hot water must be added. The pint of lac
solution ought, however, to be emulsified in the gelatine solution.
To use the emulsion, it is warmed, and the paper immersed in or floated
on it for three minutes. When dry, the coated surface is floated in the
following for a couple of minutes:--
Ammonium chloride 10 grains
[28]Magnesium lactate 10 "
When dry, it is sensitized on a moderately strong bath (that given on
the last page will answer).
If more vigour in the resulting prints be required, it is floated on:--
Citric acid 5 grains
White sugar 5 "
This last bath improves by use, probably by the accumulation of silver
nitrate from the sensitized paper.
Any of the toning baths given in Chapter XII. will answer, though Mr.
Cooper recommends:--
Solution of gold tri-chloride
(1 gr. to 1 dr. of water) 2 dr.
Pure precipitated chalk a pinch
Hot water 10 ounces
2 dr. of sodium acetate are to be placed in the stock-bottle, and the
above solution filtered on to it. This is made up to 20 ounces, and is
fit for use in a few hours; but it improves by keeping.
In commencing to tone, place a few ounces of water in the dish, and add
an equal quantity of the stock solution, and if the toning begins to
flag a little, add more of it from time to time.
With the resin processes over-toning is to be carefully avoided.
Resinized paper may be obtained from most photographic dealers,
we believe, and for some purposes is an admirable substitute for
albumenized paper.