The Barnet Book of Photography Part 20

THE CHARACTER OF THE NEGATIVE FOR PLATINOTYPE.

In the earlier days of platinotype printing it was generally insisted upon that the most suitable negatives were such as we should describe as somewhat vigorous or "plucky." Whether it is that some alteration has been made in the manufacture of the paper or that taste as regards what const.i.tutes a good print has changed, I cannot say. Certain it is that in the experience of a good many, a "plucky" negative is by no means essential to the production of a good platinotype print.

The soft, delicate negatives, of which the best professional portrait negatives are a good sample, yield the best possible results, whilst with the CC paper, negatives so thin and delicate as to be suitable for hardly any other printing process, give all that can be wished for.

Much, of course, will depend on the kind of print desired and the paper used, and here it may be remarked that from a given negative the different kinds of platinotype paper give different results.

From a given negative the hot-bath papers yield the greatest amount of half-tone, the hot development tending to yield flatter results.

Next comes the smooth, cold-bath paper, and finally as yielding the maximum amount of vigour is the CC paper. Hence if we make our negatives specially for our chosen printing process, a stronger negative will be needed for S, RS, A and C than for the AA and CC, whilst for the latter a negative distinctly erring on the side of extreme thinness will be best.

If a negative gives prints which are too weak and flat for our purpose, a great improvement may be effected by printing through blue gla.s.s. If on the other hand the prints are too hard and harsh in contrast, it is advisable to print through "signal" green gla.s.s.

TONING PLATINOTYPE PRINTS.

Several formula and methods have been published from time to time, the object of which is to change the colour of the platinotype print by subsequent staining or toning, and whilst by such methods pleasing colours may sometimes be obtained, they possess an element of uncertainty, and must not be too much relied upon. An exception in this respect must, however, be made in the case of what is known as Packham's method, the effect of which is to change the black platinotype to a sepia brown, or a brown slightly tinged with green.

The necessary "tinctorial powder" must be obtained from Mr. Packham or through a dealer. To prepare the bath a packet of this powder is dissolved by boiling for three or four minutes in five fluid ounces of water, to which when cold add one ounce methylated spirit. This forms the stock solution and will keep for a long time if well corked. For use add thirty or forty minims of the stock solution to one pint of water, and in this steep the prints, turning them over frequently. Toning may occupy several hours. To expedite matters, the dilute solution should be made with water of 150 F., and the bath maintained at this temperature as in the case of hot-bath development. As soon as the desired tint is secured, remove the prints and wash well in three changes of cold water.

Prints may be so treated at any time after they have been made.

Glycerine developed prints are not suitable. Prints must have been very thoroughly washed, so as to free them from every trace of acid, also thoroughly fixed in acid if they are to be "toned" by Packham's method. If after "toning" and was.h.i.+ng the whites of the print appear to have suffered, the prints should be placed for five or ten minutes in the following bath, which should be kept at a temperature of 180 F.

Castille soap 40 grains Bicarbonate of soda 80 grains Water, hot (180 F.) 1 pint

This will clear the whites and intensify the colour generally.

Platinotypes may be toned to a red-brown by uranium nitrate, or to a bluer colour with chloride of gold. They may also be intensified by pyrogallic acid or hydroquinone, but as the purpose of this article was merely to give simple working instructions for platinotype printing for the beginner, he may defer the consideration of such side issues until he has become _au fait_ in the production of a good platinotype print.

_A. Horsley Hinton._

_Contact Printing on Bromide Paper._

[Ill.u.s.tration]

It is well to bear in mind at the outset that bromide paper is extremely sensitive to light, almost as much so as is a rapid dry plate. For this reason, it is obvious that it must not be carelessly exposed to actinic light. All manipulations except the actual printing must be conducted by red or yellow light, such as is allowed to pa.s.s through gla.s.s of these colours.

For evenness of result, it is better to use a lantern than daylight, because the fluctuation in intensity of the latter is very misleading and liable to lead to failures through over or under development.

The actual colour of the light, also, is of far more importance than one would suppose: ruby light tends to give one the impression that development is complete long before that is the actual case; it is also somewhat more difficult to handle the paper satisfactorily by this light than by a good yellow.

For these and other reasons I strongly recommend the use of yellow light, a thoroughly safe one being given by gas or lamplight pa.s.sing through one sheet of yellow gla.s.s and one thickness of "canary medium."

This light, while being absolutely safe, gives such perfect illumination that it is as easy to control and estimate results as it would be by ordinary unfiltered gaslight.

If a ruby glazed lantern is already in use for negative work, it can readily be prepared for bromide printing by merely removing the ruby gla.s.s and subst.i.tuting the yellow and canary medium. With these brief hints as to illumination, let us consider the entire process in its various stages.

_Unpacking the Paper._--The sensitive paper is generally packed in envelopes sufficiently opaque to protect it from the admission of light. The packet must be opened in the dark-room from which _all_ light (even stray streaks beneath the door) is excluded, excepting only that given by the yellow glazed lantern. The outer envelope being carefully undone, an inner cover will be found and these wrappers should be placed on a dry table while a sheet of the paper is removed.

It is a good plan to have a "light-tight" box (obtainable from any dealer) in which to put the paper after unpacking it; this prevents loss of time and awkwardness of handling in having to replace the paper in its wrappers each time a piece is withdrawn for use.

When several prints from one or more negatives are required, it is an excellent thing to have two of these boxes, one for the unexposed paper and one in which to put the prints as made until all are ready for development.

_The Cla.s.s of Negative._--Bromide paper gives us a great command over results; in fact, so vast is the control we may exercise that it is possible to secure good results from almost all cla.s.ses of negatives, from mere ghosts to those with density almost equal to that of a brick wall. But there is, of course, a cla.s.s of negative that gives a good result with the least expenditure of skill, such a one is generally known as of average density, having a full scale of gradation with high-lights dense, yet not so opaque as to prevent you seeing a window clearly defined when looking towards it _through_ the densest parts of the film, such as the sky, for instance. Another way to test the density is to put the negative, film side down, on some large print on white paper, the large letters should be just visible through the sky, but the smaller print should not be readable.

That is the cla.s.s of negative usually considered in Instructions for Use, as an "average" negative.

_The Sensitive Side of the Paper._--A difficulty sometimes occurs in telling which is the sensitive side of the paper: this may be easily ascertained by the appearance of the edge, which turns slightly inwards _towards_ the sensitive side. This is quite apparent to the sense of touch as well as sight. Some people moisten their finger and thumb and squeeze the paper and see which sticks (the sensitive side), but that is a dirty method and quite unnecessary.

_Printing from the Negative._--Having unpacked the paper, after making sure that all but the yellow (or ruby) light has been excluded from the room, we are ready to print.

For this purpose, different workers favour different cla.s.ses of light: one prefers gaslight, another swears by magnesium ribbon, and some even prefer the light of day.

Personally, I favour ordinary gaslight pa.s.sed through a No. 5 Bray's burner, because it is quite rapid enough for all practical purposes and is perfectly under control and free from serious variation.

[Ill.u.s.tration: Fig. 1.]

The burner should be within easy reach of the worktable and should be fitted with a byepa.s.s to obviate the necessity of continually striking matches. Several years ago I had my bromide printing rooms fitted with an excellent lantern of this cla.s.s in which the byepa.s.s was connected to two jets (one inside and the other outside the lantern) in such a way as to turn down the white light with the same movement that raised the coloured light, and _vice versa_. By this means no gas was wasted and the simple action of pulling or pus.h.i.+ng a lever operated either light at will. By placing the same lever "amids.h.i.+ps," both jets were lowered to the point of invisibility and could so remain for days at a time, yet always ready at a moment's notice. The accompanying sketch (fig. 1) will give some idea of its construction.

If the dark-room is small, and s.p.a.ce is an object, the sink may be fitted with a wooden cover and this may be used as a table for printing the paper, but care must be observed to avoid the slightest moisture upon it or satisfactory work is impossible and the negatives may be ruined. In a large room, it is much better to have an ordinary kitchen table removed some distance from the sink; with this and a comfortable chair bromide printing is a very pleasant occupation. The following sketch (fig. 2) will explain the arrangement of the table, and it applies equally well to the movable top of the sink.

[Ill.u.s.tration: Fig. 2.]

Supposing that some arrangement of this sort is devised, we must unpack some bromide paper and put it in its box and then put a negative of "average" density in an ordinary printing frame. On the film side of the negative we must now place a sheet of bromide paper with its sensitive side in contact, replace the back of the frame and it is ready for exposure. Before exposing it, _make sure that both boxes are shut_ or their contents will be ruined the moment the white light is turned up.

Upon reference to the instructions that accompany each packet of bromide paper, you will observe a certain number of seconds'

exposure is advised at a certain distance from the light; in the case of the Barnet extra rapid paper the time is given as about four seconds at a distance of eighteen inches.

When all is ready for exposure, place the printing frame upright opposite the lantern at the mark indicating eighteen inches (see fig. 2), note the time on the seconds hand of the clock and throw the lever over for white light for four seconds and then reverse it.

Remove the paper and if many are likely to be required from that negative, it would be well to develop the first print in order to judge as to the accuracy of the exposure. If over or under-exposed, the time must be reduced or lengthened as required. When the best time and distance has been ascertained for a certain negative, mark it with a narrow strip of paper bearing full particulars for future guidance, such as: "4 sec., 18 in., No. 5 Bray;" in this way absolute correctness of future exposures is a.s.sured. Of course, if gas is not obtainable, magnesium ribbon may be used instead. In this case the negative would be marked "1 inch (or more) ribbon, 3 ft.

distant," as the case may be.

_Using Masks and Discs._--Prints are sometimes required with an oval (or square) centre and white margins: this is effected by interposing a black mask of the desired size and shape (obtainable from all dealers) between the negative and the sensitive paper. The black paper prevents the pa.s.sage of light and leaves white margins to the print. If grey margins are required, a disc (to fit the mask) is attached to a sheet of gla.s.s the same size as the negative and arranged so that registration is easily effected; the print is first made with a mask and is then placed in contact with the disc and plain gla.s.s (the negative being removed from the frame), and again exposed for a second to the light. If a black border is required the exposure of the margin must be extended three or four seconds.

_Vignetting._--To vignette bromide prints, the printing frame must be covered with a piece of cardboard in which a small hole (about 1-1/2 inches by 1 inch for a cabinet head and bust) is pierced. The hole _must_ be covered with a sheet of white tissue paper which will diffuse the light and cause it to travel without harsh lines beneath the opening, and make the print with perfectly gradated edges. It is sometimes an advantage to move the negative while printing vignettes; but it is not absolutely essential if the hole in the cardboard is not too large and if the card is removed some little distance from the negative. If the card is too close to the negative, the gradation will be abrupt and the vignette will not look well.

_Cloud Printing._--This requires some care in order to avoid harshness and sharply defined lines. If the sky of the negative prints white, the addition of clouds from another negative is not difficult; but if it is at all thin, the entire sky must be carefully painted out with a deeply opaque pigment in order to make it quite dense and unprintable.

As a bromide print cannot be examined while in progress: that is, cannot be seen at all before development, careful registration is desirable in order to prevent printing the clouds across the landscape instead of above it. To do this an opaque mask should be made thus: Make a print from the negative on P.O.P. and, without fixing or toning it, cut it carefully in two parts following the horizon line as nearly as possible, then expose to light, until quite black, that part representing the landscape. Attach this to the gla.s.s side of the cloud negative (with the paper side of the P.O.P. in contact) and see that the bottom edge and the right corner of the paper and gla.s.s (viewed from the gla.s.s side of the negative) exactly coincide. To make use of this arrangement, you first make a print from the landscape negative, making sure that the negative and paper are firmly pressed against the bottom and left-hand side of the printing frame when looking towards the film side of the negative; mark the registered corner with lead pencil thus =L= in order to prevent mistakes in the second printing.

To print the clouds, you put the negative in the frame and press it well home to the left-hand corner and the base of frame (looking at the film side, of course), and then put the print in contact with the same precaution and replace the back. Now take a piece of brown paper with one edge roughly torn in shape of the horizon line of the mask and cover the entire negative on the gla.s.s side. Hold the covered frame in your hands at a distance of (say) four feet from the gas and turn on the white light. Directly the light is up, draw the paper slowly downwards until the horizon line is just pa.s.sed, and then _immediately_ begin to slowly push it upwards towards the top of the sky. Do this steadily and slowly for (say) four to six seconds, according to the density of the cloud negative. With a good thin cloud, four seconds should be quite enough, but you can easily settle this point on developing the first print.

_Printing from Dense Negatives._--Dense negatives require much longer exposures than those of "average" (or ideal) density. This may often be prolonged to twice or three times the normal exposure at the same distance. A yellow coloured negative increases the exposure greatly, as much as ten to thirty times the normal frequently being requisite to get a decent print. An over dense negative that gives very harsh prints by other printing processes can be made to yield prints of exquisite softness on bromide paper by giving a full exposure at a _short_ distance from the gas.

[Ill.u.s.tration: CUPBOARD LOVE. T. LEE SYMS.]