CHAPTER XIX.

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.