The Barnet Book of Photography Part 21

_Printing from Thin Negatives._--Thin negatives on the other hand, require quite different treatment. In order to get plucky prints from very thin negatives, useless in other processes, we must give a very brief exposure at some distance from the gas; and here it may be well to note that removing the negative to a greater distance from the light is equal to decreasing the actual time of exposure and has other advantages in connection with thin negatives with which theory does not seem to agree. To print from a very thin negative, then, instead of four seconds at eighteen inches, let us cover it with a sheet of tissue paper and give it four seconds at a distance of three or four feet and note the result on development.

If it appears to be over-exposed, we may reduce the time of exposure to three seconds at the same distance and modify the developer, as will be explained later on.

_Development of Prints._--All my remarks in this article apply equally to most commercial brands of bromide paper; but it is only fair to state that they are particularly intended for that made by the firm of manufacturers publishing this book. Development, and so on, is very similar with all makes of paper, but most of my recent experiments have been made on the "Barnet" matt surface bromide.

I shall presently describe the use of several well-known developers, but it must be well understood that, whatever formula is adopted, a preliminary soaking of the print before development must be done.

When we are about to develop a number of prints we must first soak them in plain cold water until quite flaccid, otherwise the application of the developer would cause the dry print to c.o.c.kle and curl, and the development would not be regular. This rule applies equally in the case of one print only as when a hundred are ready for development; a prolonged soaking in plain water having no ill effect.

_The Iron Developer._--This is one of the developers most frequently recommended for bromide work, but personally I never advise its use (especially by a novice) because the use of the acid clearing bath, which is an essential part of the process, is so frequent a cause of disaster and yellow prints. The Barnet formula is as follows:--

A.

Pota.s.sium oxalate 1 lb.

Pota.s.sium bromide 5 grains Hot water 48 ozs.

B.

Iron sulphate 1 lb.

Citric acid 4 drams.

Hot water 32 ozs.

To six ounces of A, add one ounce of B; this order of mixing must be observed or a dense precipitate of ferrous oxalate will be formed.

Place one of the soaked prints face (which may be distinguished by its "slippery" surface) upwards in a clean porcelain dish and pour the developer over it as evenly as possible. With this developer, the image comes up very rapidly, so that it is not advisable to try and develop more than one at a time. If the first print of a batch appears to be over-exposed, that is, if it flashes out instantly and the high-lights become rapidly clouded, add to each ounce of mixed developer from 10 to 30 drops of a ten per cent. solution of pota.s.sium bromide which will act as a restrainer, r.e.t.a.r.d development, and keep the high-lights clear while the shadows acquire density. Under-exposed prints can rarely be made to give pa.s.sable results with ferrous oxalate. The addition of a trace of hypo to the developer has been recommended for bringing up their detail, but the result is far from good.

As soon as development is complete the prints must _not_ be put in clean water, but must be transferred direct from the developer to the following acid bath:--

Acetic acid 1 dram Water 32 ounces

After an immersion of one minute, the operation must be twice repeated in similar baths that have not been previously used; this is to remove the iron from the print. A thorough washing must next be given to remove the acid and the print may then be fixed for at least fifteen minutes in

Hypo 2 ounces Water 20 ounces

After fixing (no matter what developer has been used) the prints must be thoroughly washed in several changes of water for at least two hours.

The chief reasons against the use of ferrous oxalate are lack of control over development and the necessary use of an acid bath.

Unless the acid bath is used, the prints will be yellow because of the iron in them, and if the acid is not entirely removed before fixing the prints will be yellow owing to the decomposition of the hypo by the acid in the print which causes deposition of sulphur.

_Metol Developer._--With this, and the other developers I shall mention, an acid bath is not necessary and so one cause of failure (and extra work) is obviated. I have somewhat amended the Barnet formula to meet the needs of workers on a small scale and have also arranged A and B to balance each other without disturbing the relative proportions of the ingredients.

A.

Metol 120 grains Water (cold) 24 ounces

Dissolve _completely_ and then add

Sodium sulphite 2-1/2 ounces Pota.s.sium bromide 15 grains

Shake until completely dissolved but do not apply heat.

B.

Pota.s.sium carbonate 350 grains Water 8 ounces

For use, mix three parts by measure of A and one part of B.

With this developer and a normal exposure, the image should appear in a few seconds and development should be complete in about two minutes. As fast as the prints are developed they should be immersed in

Salt 2 ounces Water 20 ounces

to stop development. When all are developed, they must be rinsed for a minute or two in clean water and then fixed. Over-exposure is remedied by the addition of pota.s.sium bromide solution (as in the case of ferrous oxalate); under-exposed prints should be developed in a weak solution such as

A 3 parts B 1 part Water 4 parts

Development will take longer, but the weaker solution will help to bring up the detail without the harshness of the shadows that would be the case if the normal developer was used.

_Hydroquinone and Eikonogen._--The advantage of combining eikonogen with quinol lies in the fact that one provides what the other lacks, the eikonogen tending to give detail without density and the quinol (in inexperienced hands) giving density without detail. The following formula will be found very satisfactory:--

A.

Quinol 40 grains Eikonogen 120 "

Sodium sulphite 480 "

Citric acid 20 "

Water to 20 ounces

Dissolve the sodium sulphite and citric acid in 15 ounces of water, then add the other ingredients and enough water to make a total bulk of 20 ounces.

B.

Sodium carbonate 60 grains Sodium hydrate 30 "

Pota.s.sium bromide 5 "

Water to 20 ounces

For use, mix one part of A, one part of B and two parts of water.

The same remarks as to over and under-exposure apply as in the case of metol.

_Toning Bromide Prints._--The "tone" or colour of the deposit depends largely upon the accuracy of exposure and the developer employed. Ferrous oxalate gives a rich black deposit, but to my mind metol and the combined eiko-quinol give tones at least as beautiful with pretty gray half-tones.

But some people prefer warmer colours, brown and red for instance, and some get brownish blacks (through over-exposure and the use of bromide) which they would like to change.

The colour of the deposit may be changed in various ways by treating the print in baths of different metals. I will give a brief outline of the methods employed, leaving readers to modify them to suit each particular case.

_Black and Blue-black Tone._--Brownish black prints can be much improved after fixing by immersion in a strong bath of gold chloride; the following is the strength used by me:--

A.

Ammonium sulphocyanide 20 grains Water 1 ounce

B.

Gold chloride 2 grains Water 1 ounce

When quite dissolved add B very gradually to A, shaking almost continuously. The fixed print should be washed for at least fifteen minutes before toning and should then be placed in a clean tray while the toning bath is poured over it. The solution must be kept moving and the print must be removed and washed directly the desired tone is reached. Prolonged immersion will cause the print to acquire a deep blue tone.

_Brown and Red Tones with Uranium._--Prints immersed in the uranium toning bath gradually become warmer in tone, changing from black to brown and brownish red until they a.s.sume a deep red nearly approaching the well-known Bartollozzi chalk.