366. While instructions for using this paper already sensitized, ready for use, will be found in the previous paragraphs, the following formula for preparing your own paper may be employed. This same sensitizing solution can be applied to a number of other surfaces, such as cloth, silk, post cards, etc.

367. Formula For Sensitizing Solution

Formula For Sensitizing Solution.

Stock Solution No. 1

Water..................

8 ozs.

Citrate of Iron and Ammonia............

1 7/8 ozs.

Stock Solution No. 2

Ferricyanide of Potassium........

1 1/4 ozs.

Water.................

8 ozs.

368. The Ferricyanide should be in clear, bright ruby crystals, and it is always well to rinse them in plain water before final dissolving, as almost all of these crystals have a slight brown coating on them and it is best to remove this. Place in a bottle and mark it Solution No. 2.

369. When the solutions are dissolved keep them in a dark place. If you do this they will keep for a long time; in fact, the bath will work better after standing for at least one week.

370. Sensitizing The Paper

Sensitizing The Paper. The best paper to use is the plain Rives paper, which can be purchased at any photographic stock house. Mix equal parts of No. 1 and No. 2 solutions and with a brush apply to the paper; or if you desire, float the paper on the solution. For the beginner we advise the cutting of a sheet of paper into small sheets, especially if you intend to float it. Place the solution in the tray (this tray should be used for nothing else but this sensitizing solution). Catch the sheet of paper at two corners, between the fore finger and thumb of both hands, and then lower it onto the solution, having the center of the sheet touch first, and then slowly lower the rest of the paper over the solution, being careful that you float the paper and get none of the solution on the back. (See Illus. No. 52.) As soon as the sheet is on the bath, raise the paper from one corner and gently remove any air-bells that may have gathered. (See Illus. No. 53.) Allow the paper to float for about three minutes, after which hang up to dry. The paper must be dried in the dark, and when dry it can be rolled up and placed in a light-tight box, or cupboard.

371. When sensitizing post cards it is advisable to do it with a brush, applying the sensitizer only to the parts of the post card on which you are going to print. Occasionally you will find that the prints look foggy, that is to say, it is impossible for you to obtain clear whites. It is then advisable to add one-half grain of potassium bicarbonate to the above sensitizer. When sensitizing post cards they should be dried as rapidly as possible. It is advisable to do this sensitizing in artificial light.

372. An excellent bath, which gives a very sensitive and quick printing paper, is made according to the following formula:

Illustration No. 52 Sensitizing the Paper   Lowering onto the Bath

Illustration No. 52 Sensitizing the Paper - Lowering onto the Bath.

See Paragraph No. 370

Illustration No. 53 Sensitizing the Paper   Removing Air bells

Illustration No. 53 Sensitizing the Paper - Removing Air-bells.

See Paragraph No. 370

(a)

Ferric Ammonium Citrate (green)..

no grains

Water ...............

1 ounce

(b)

Potassium Ferricyanide.................

40 grains

Water ................

1 ounce

Mix in equal parts; keep in the dark, and filter just before use.

*If the ordinary brown citrate is used, the formula should contain 80 grains, and the ferricyanide should be increased to 60 grains. This solution is applied to the paper in exactly the same manner as the first formula given.