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The Barnet Book of Photography A Collection of Practical Articles

Ordinary transparency tissue will serve every purpose


The

glass plates are carefully selected, free from bells, scratches, and other defects; thoroughly cleaned, either by acid or rubbing with plate powder to remove every trace of grease, and then coated with the gelatine solution, and placed in a rack to dry; when dry, exposed to light to render the film somewhat insoluble. It is not desirable to print until the film is absolutely hardened throughout. The print adheres firmly to the plate when the substratum is not over-printed.

A positive intended for projection should show clear glass in the highest lights without undue density in the shadows, all details plainly seen--in a word, quite transparent.

Positives intended for enlargement must be fully exposed--that is to say, every detail on the highest lights brought out, but no more; beyond that point there is nothing to be gained. Over-printing in the transparency tends to bury detail in the shadows of the enlarged negative, and to blend the highest grades in the high-lights, reducing the roundness or modelling of the picture.

In the case of very hard negatives intended for enlargement, the usual treatment is to sun the whole surface of the transparency in order to secure detail in the high-lights. A moment's consideration will convince any practical printer that nothing but injury to the final print can result from such treatment of the transparency. The high-lights are degraded,

the details in the shadows further buried. The better method is to make an extra special transparency tissue, for the printing of such hard negatives, containing a greatly reduced proportion of pigment to gelatine. Such a tissue permits greater depth of printing, retains all details in the shadows and high-lights, and, in fact, enables the enlarger to produce a negative that will yield a thoroughly satisfactory print.

REPRODUCED NEGATIVES.

In making reproduced negatives from hard originals, ordinary transparency tissue will serve every purpose. The transparency is printed in the usual way, and developed on a prepared glass plate; when dry a negative is printed from the transparency without special treatment and also developed on glass, when a decided reduction of density will be found to have taken place. The reproduced negative will possess all the good qualities of the original, plus improved printing quality. It is only in the case of extremely hard negatives that the extra special tissue is required.

If a perfect reproduction of an original negative is required, the transparency must be printed either in very weak light or in direct sunlight. Either method gives a brighter image than that produced in ordinary diffused daylight. The same method must be adopted in printing the negative.

_Note._--Care must be taken when direct sunlight is used to see that the pressure frame and everything in and about it is thoroughly dry, otherwise the tissue may stick to the negative, spoiling the print and probably the negative also. It must also be noted that two tints, printed in direct sunlight, although of apparently the same depth, mean quite as much as three such tints printed in diffused light.


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