Over-exposure adds an equal amount of silver to all parts of the negative, but over-development of properly exposed negatives adds proportional amounts of silver to the various parts of the negative. If you wish to secure 50% proportional reduction you must take 50% of silver from the highlights, which is a great deal- 50% from the middle tones, which is a much smaller amount, and 50 % from the lower tones and shadows, which is a very little.

To secure this result the action of the reducer must take away silver in the same proportion as the developer has deposited it, so that the result after reduction is the same as if the negative had received less development in the beginning.

The action of such a reducer is remarkable and it is certainly very useful. It has often been claimed that Permanganate would reduce proportionately - but such is not the case. The following is the only known reducer of the kind and as it has been in use less than two years it may be new to you:

Proportional Reducer


Water......... 82 ozs.

Permanganate of Potash ............. 4 ozs.

10% Sulphuric Acid .............1/2 oz.


Water.........64 ozs.

Persulphate of Ammonia ........... 2 ozs.

For use, take one part of A to three parts of B. When sufficient reduction is secured the negative should be cleared in a 1% solution of bisulphite of soda or metabisulphite of potash. Wash the negative thoroughly before drying.

Proportional Reducer StudioLightMagazine1918 103


By T. L. Halldorson

Middle Atlantic States Convention

Once your apprentice has had the use of these reducers thoroughly explained to him he should be required to reduce a number of negatives. He should first choose the proper reducer for each of a number of negatives and be set right if he makes the wrong selection.

He should then be given a standard to work to and should practice reduction until he is able to secure results that are, by comparison, practically uniform.

For the intensification of negatives we recommend the method of bleaching with mercury and re-developing with sulphite of soda. The same precautions must be observed as when reducing negatives, that is, they must be thoroughly washed and fixed to insure even intensification, permanency and freedom from stains.



Water ... -..... 12 ozs.

Mercuric Chloride .... 120 grs.

Potassium Bromide .... 120 grs.


Water......... 8 ozs.

Sulphite of Soda..... 1 oz.

Immerse the negative in solution A until the image is thoroughly bleached through the film. Then rinse well and blacken or re-develop in solution B. If intensification is too great the negative may be dipped into hypo which will immediately start a reducing action. If left in the hypo too long the negative will be reduced to its original density.

Local intensification is difficult, but there is a very simple method of securing results without taking chances. For example, you have a negative of a bride in which the white drapery is perfect but the shadows are very much in need of intensification. If the entire negative is treated the drapery will be too dense.

Instead of locally intensifying the shadows, reduce the white drapery, thoroughly wash the negative and then intensify. The white drapery which was reduced will be brought back to its original density but all other parts of the negative will be intensified.

When you have selected a number of discarded negatives for the apprentice to work on, be sure that they remain in a washing tank long enough for the gelatine films to be thoroughly soaked up before they are treated.

Don't overlook the

Kodak Advertising Competition

Intensifier StudioLightMagazine1918 105


By T. L. Halldorson

Middle Atlantic States Convention