When the paper comes off, wash the print gently with the warm water. The pigment not acted on by light will gradually loosen and fall away from the tissue, and the image will begin to appear. Now, if the printing is correctly done, the development will be at a normal speed and well under control; but if an overexposure was made, somewhat hotter water will be required to dissolve away the gelatine pigment. Conversely, if an under-exposure is indicated by a wholesale falling away of detail, we must quickly arrest development by cold water, and modify the developing temperature to suit. Extreme latitude is thus secured. Skillful carbon printers lose few sheets of tissue by errors.

When development is complete we stop it by immersion in cold water. It should be rinsed till the drippings are quite clear. After this, a bath of alum serves to move the bicarbonate and to harden the gelatine film.

It is here necessary to explain the "safe edge. " We wish to prevent the light from acting clear to the edge of the tissue, for in this case the paper back would cling to the tissue and tear away pieces of the image. By putting on the safe edge we preserve a soluble border of gelatine around the printed image, and the paper back detaches easily.

The "actinometer" makes a better printing guide than the plan above suggested. It may be constructed in a few minutes spare time. Get a small printing frame about 4x5, with a glass to fit. Cut a strip of tracing cloth, or onion skin paper, about 4 inches long, and an inch wide. Next cut a similar strip of 4 3/4, 4 1/2, 4 1/4 in., etc., of the same width as the first. Lay the set over one another on the glass so that the longest is on the bottom, and we will then have a series of steps and cover the rest of the clear glass on the plate with black paper. Number with opaque ink the various steps from one upwards.

The actinometer is used in place of the trial negative mentioned before. One negative may need printing till the actinometer shows light action under the number 8, for instance; another may need but 5, and so on. Once the correct number is found it is marked on the negative. It should be possible to make perfect and uniform prints from a negative from here on, as the actinometer is an accurate measure of light.

As stated before, the single transfer process is only applicable to a few subjects. A portrait is allowable in single transfer, and landscapes in an artistic sense. There is, however, a curious difference between the two sides of a face in an ordinary person, and while always recognizable, a single transfer print sometimes gives queer expressions to familiar faces. Similarly a landscape reversed from right to left will sometimes be unrecognized by people who know the locality well. A picture including a sign of any kind would, of course, be ridiculous, as the printing of the sign would run backward.

The description of the carbon process, like many another of the photo operations, is much more complicated than the operation itself. Thus, in the soaking of the tissue before the first transfer, a little judgment must be used. Too long an immersion in water spoils the sticking property of the tissue. When the tissue is hard and brittle it curls inward in the water and must be soaked till it starts to flatten out and become limp. But as soon as the flattening commences it indicates the time for squeegeeing to the temporary support. If the tissue be left in the water till it curls outward, the chances are much against its adhering at all.

The double transfer process is quite easy after a little experience with the simple single process. We need now, in addition to our outfit, some temporary supports. These may be of ground opal, or the more convenient "flexible temporary support " may be obtained at the dealers. Note that the temporary support must be waxed thoroughly else the print would stick to it permanently and could not be transferred.

The waxing solution is made as below:

No, 1. Benzol, 1 oz., brown wax, 3 gr.

No. 2. Spirits turpentine, 1 oz., resin, 12 gr.

Dissolve separately and mix. Pour a little on a cloth and rub over the temporary support, polishing with a second cloth.

The flexible temporary support is covered with insoluble gelatine and shellac. The waxing prevents the tissue from sticking fast at the last transfer.

The exposed print is carried through the preliminary processes just as for single transfer. We are now ready to make the last transfer, and while the developing operations are going on, a piece of commercial " double transfer paper" should be soaking in warm water. When the transfer paper becomes shiny we may then proceed to the final transfer.

The developed print on the temporary support is fixed from bichromate by the bath of alum. It is then thoroughly rinsed and put away to dry. The transfer should be made as soon as the drying is complete. We bring the shiny transfer paper of the preceding paragraph into immediate contact by squeegeeing. This serves to remove air bubbles and superfluous moisture.

We next dry the tissue, double transfer paper and attached temporary support in a warm current of air, after which the temporary support may be removed. The tissue will adhere to the final support if all the operations are correctly performed, and the image now shows in the correct position.

Failure to leave the temporary support shows incomplete waxing; failure to stick to the permanent support shows this support to have been incompletely sealed. If ground opal has been used for a temporary support the print takes on a matt surface, but remains smooth if the commercial support is used.

We come now to a most curious property of the carbon process which is used by experienced carbon printers with great success. We refer to the continuing action of light, which is the property of exposed carbon tissues to gain detail without further action of light when not developed immediately after printing. If we have a batch of carbons which do not develop fully, we may set them aside a day or so, and the remainder of the lot will develop perfectly well. A carbon printer of long experience uses this property to save time in printing when rushed. He prints several actiuometer tints short of the correct time, then lets the tissue rest and gain density over night.

The keeping quality of sensitive tissue is fair. It is wiser to make for immediate needs, however. Tissue kept too long becomes insoluble and won't develop. The same defect is caused by dampness. The correction of these defects is quite obvious.

Another cause of insolubility comes from acid bichromate of potash or from impurities in the chemical. Slow drying also produces bad effects. The drying, however, in sensitizing or in the ordinary processes should never be greatly forced. A natural drying is preferable in every branch of photo work.

Before squeegeeing the tissue to temporary supports we should blot off the excess of moisture, otherwise spots may develop on the finished prints. Drying between blotters is recommended to remove the moisture.

Tissue which has just been sensitized does not work well; after two or three days the results are more even and satisfactory. The newly sensitized tissue is lacking in details in the high lights, which defect may also come from underprinting or too hot developing bath.

An operation called " sunning " is recommended by many professionals. This a few seconds exposure of the blank sensitized tissue to sun before placing in the printing frame. It has the effect of tinting over the high lights and making the surface of the tissue entirely insoluble. It, therefore, adberes perfectly to the supports. Sunning is almost a necessity for prints with extreme contrasts.

To retouch or spot out defects, use some of the first drippings in the development. Obviously the color matching will be perfect.

Carbons may be transferred to other supports than paper. If wood, canvas, stone, etc., are used, it is first necessary to prepare the surface with gelatine made insoluble. This may be done by means of chrome-alum, or some of the gelatine may be treated with bichromate and a vigorous sunning given to the prepared surface.