SECTION II.. _imperfections in Paper Positives._

Imperfections in Paper Positives.

1. The Print marbled and spotty.--The quality of the paper is often inferior, which causes it to imbibe liquids unevenly at different points; or the amount of Silver in the Nitrate Bath is insufficient. In this case the spots are often absent at the lower and most depending part of the sheet, where the excess of liquid drains off.

2. The Print clean on the surface, but spotted when held up to the light.--In this case the spots are probably due to imperfect fixation (see p. 129).

3. The Print becomes pale in the Hyposulphite Bath, and has a cold and faded appearance when finished.--The Chloride of Silver in the paper may have been in excess with regard to the free Nitrate of Silver; which is especially likely if no bronzing could be obtained by prolonged action of the light, or if a weak solution of Nitrate of Silver was laid on with a brush, or by a glass rod. Prints formed on paper which has been kept too long after sensitizing present the same appearance, the free Nitrate of Silver having entered into combination with the organic matter.

4. Yellowness of the light parts of the proof.--The following causes are likely to produce yellowness:--acidity of the fixing and toning Bath (p. 139),--its action continued for too long a time,--the first washings of the proof not performed quickly,--the toning Bath laid aside until it had become decomposed and nearly useless,--the paper kept for several days after sensitizing.

A creamy yellowness is also common in Prints toned by Sel d'or, when the Hydrochloric Acid has been omitted from the formula; the proof exposed to light during the toning and fixing process; or too long a time allowed to elapse between the toning and fixing. It is also more frequently met with on albuminized paper.

5. Intense bronzing of the deep shadows.--In this case the Negative is in fault; remedy the evil as far as possible by printing on paper containing but little salt.

6. The definition of the Print imperfect, the Negative being a good one.--Much will depend upon the quality of the paper. Towgood's Positive gives good definition. The use of Albumen will be a great advantage. Citrate of Soda (p. 246) will also improve the definition on plain paper.

7. Markings of a yellow tint in the dark portions of the Positive.--These are common on Prints toned without Gold; care should be taken not to handle the paper too much, either before or after sensitizing; to wash the prints in a clean vessel; and not to lay them down whilst wet on a wooden table or in contact with anything likely to communicate impurities.

8. Small specks and spots of different hinds.--These, when not corresponding to similar marks upon the Negative, are usually due to metallic specks in the paper; or to insoluble particles floating in the bath.

9. Markings of the brush in Ammonio-Nitrate pictures.--In this case there is probably an excess of Ammonia, which dissolves the Chloride of Silver. Add a little fresh Nitrate of Silver, or use the Oxide of Silver dissolved in Nitrate of Ammonia (p. 249).

10. Marbled stains on the surface of the Print.--Draw a strip of blotting-paper gently over the surface of the Nitrate Bath before sensitizing the paper; and see that the sheet does not touch the bottom of the dish.

11. Streaks on Albuminized paper.--Apply the Albumen more rapidly and evenly to the paper. If this does not succeed, add a little Ox-Gall (p. 243).

12. Removal of the Albumen from the paper during sensitizing.--The Nitrate Bath is probably alkaline (see page 89).