Fig. 3.
We now put out our first piece of platinotype paper to print, and alongside it so as to receive the exact same amount of light, we place our actinometer.
The first print must admittedly be guess-work.
After an interval of time, which may vary from say fifteen minutes to an hour according to the amount of light, we will withdraw the frame containing the platinotype print, and simultaneously turn the actinometer over with its face down, thus stopping its printing whilst examining the platinotype.
Retiring from the light we examine the progress of printing precisely as in silver printing, and we shall probably find that the image on the negative is now faintly visible on the platinotype paper, impressed in a sort of warm grey colour.
If the darkest portions are of about the tint which we might produce by shading with an H pencil on a piece of primrose yellow or pale buff paper, we may reckon that the print has been sufficiently exposed.
Now refer to the actinometer and see what has taken place on the silver paper which we put into it. Probably while the platinotype paper has been reaching the required depth of printing, the silver paper has also registered the image of the strips of paper, and has become printed through up to the fourth or fifth step of the tissue strips, showing on each strip its letter in white. Make a note of the highest letter visible and proceed to develop the platinotype print. If upon development the print is weak and grey, lacking depth or intensity in the deepest shadows, and having blank and detailless whites for the higher tones, we may reckon that our print is under-exposed. The letter visible then, with that particular negative is not sufficient. We then shift the paper in the actinometer so as to get a fresh portion under the tissue strips, or we substitute a new piece. We refill the printing frame and print again until the actinometer registers one, two, or three more steps and letters, and then try again. If, however, in the first case the platinotype print upon development gives a heavy dark print, with the details in shadows blocked up, and the high-lights grey, the whole possessing an overdone appearance, then in our second attempt we shall stop printing when the actinometer records some one or two letters less. But we may be more fortunate in our first attempt, and the print may be about right. In that case we mark on that negative in some way the tint or step or letter in the actinometer at which we arrested action, and henceforth, no matter the time of year, hour of the day, or latitude, that negative will give a similar print if stopped in accordance with that memorandum which it bears.
If, however, we do not hit the right exposure the first time, we are pretty certain to do so the second, or at the most the third time, and having done so, we have not only an infallible guide for all subsequent prints from that same negative, but we have also some sort of index to base our calculations on for other negatives. Thus if we at once proceed to print from another negative, that is, before any considerable alteration takes place in the light, we may by comparing the negatives at least estimate what will probably be the second negative's printing letter or step on the actinometer. Sooner or later every negative (especially those from which we anticipate wanting subsequent prints) should bear either on the negative itself, or else in a carefully kept register or note book its correct printing letter.