تويت
التصوير الفوتوغرافي الحديث
التقنيات المهنية المتقدمة ..
تحسين الطباعة ..
التخفيض المحلي للمطبوعات الجافة
تقليل البقع للطباعة
LOCAL REDUCTION OF DRY PRINTS
You can re - soak dried prints in hypo and reduce them with ferricyanide alone , using the technique just given . However , there is much less likelihood of stain if the print is soaked in plain water and the combined hypo - ferricyanide solution used .
First soak the prints until they are thoroughly limp . After they are properly soaked and not before , prepare the reducing solution . Since Farmer's reducer keeps only a few minutes after mixing , it should not be prepared until you are ready to start using it . The following proportions of the formula given earlier in this Assignment are recommended :
25 % hypo solution - - 1 ounce
10 % ferricyanide solution - - 1/4 ounce
Water - - 6 ounces
This is a fast working solution , so you may find it easier to use half the quantity of ferricyanide ( or double the water if you do not have an accurate small graduate ) .
Place the wet print face up on the flat surface and wipe off all the surplus water with a soft rubber squeegee . Dip a small swab of cotton into the reducer , squeeze out the surplus to prevent dripping and apply it to the print . From here on you use exactly the same technique as outlined in detail in the preceding pages - except that you omit the hypo soak at intervals . Instead , wash out the reducer thoroughly , using lots of water and a large dripping swab of cotton , or better still , play hose on the print if you can . After reduction is complete , fix and wash thoroughly in the usual way .
SPOT REDUCTION OF THE PRINT
Up to now we have been dealing with wet prints and for a very good reason . We have been concerned with reducing either the entire print or poorly defined areas . The water in the emulsion was needed to allow good diffusion of the reducer so that it would act uniformly over the area worked on and diffuse out imperceptibly from it , thus avoiding sharp tell - tale lines between these areas and the rest of the print .
There are times , however , when we do not want to diffuse edges at the spotting zones . For example , a black spot in the sky caused by a clear speck in the negative must be cleanly removed - there must be no perceptible diffusion of the reduced zone . Fine telephone lines running across a landscape present a similar problem . For such work a minimum of diffusion and a maximum of accuracy and sharpness are necessary - and for such work the minimum amount of water must be used . This means a dry print and minute amounts of very concentrated solutions .
For spot reduction you need concentrated Farmer's reducer , two small pieces of clean white blotter , two spotting brushes ( No. 0 and No. 3 ) , plenty of good light and , of course , the print .
With everything in readiness , mix the hypo and ferricyanide . Because it will be applied to the print in very small quantities with a brush that is barely moist , the reducer may be used full strength , one part of the hypo solution to two parts of the ferricyanide solution . If you don't have a small graduate , measure out the required quantity of each stock solution you want with a medicine dropper . Dip your spotting brush into the reducer and take off the excess on the side of the graduate . The brush is still much too wet , so dry it by drawing it across one of the blotters with a slight rotary motion . This motion will cause the brush hairs to come to a fine poin thus permitting you apply the reducer to the print exactly where you want it without fear of spreading . ( See Figure 17 ) You should wipe the brush on the blotter this way until it is almost dry . The idea is to use such a small amount of solution that when it is applied to the print there is not enough water to penetrate deeply or to diffuse beyond the actual line of contact between the brush and paper .
Figure 17 Removing black spots with concentrated - ferricyanide solution .
Hold the brush almost vertically over the spot you want to remove . If the spot is elongated , draw the brush along the spot in the direction of its maximum length if the spot is round , work the brush in a circle , taking care to cover its entire surface . Do not press downward ; it is the chemical action and not the friction that does the work . Keep the area of contact between the brush and paper as small as possible , because that is the only way you can do accurate work .
In a little while , the reducer will begin to take hold and you will see the spot beginning to lighten . When it is still a trifle darker than the surrounding area , blot it carefully with a clean blotter to pick up the reducer , and go on to the next step .
It is best to stop just short of the right point . If you have not dried your brush sufficiently , the emulsion will take up so much reducer that it will not be entirely exhausted by the silver going into solution , and so the action will continue even after you have blotted the surface solution off the print .
After you have worked on the second spot , you can go back to the first again and look at it carefully . If it is still too dark , apply more reducer little by little until the spot disappears .
When you are through spot - reducing a print , wash it for ten minutes to remove the ferricyanide and then fix it for at least five minutes in fresh hypo solution . Your regular acid hypo can be used - provided it is fresh - but you will run into less staining complications if you use a fresh non - acid fixing solution made by dissolving about 8 ounces of hypo in a quart of water . The strength of the solution is not critical , so you can simply measure out 8 ounces of crystal hypo , by volume , in a graduate instead of weighing it .
After reduction is complete , wash and dry the print in the usual way . However , before washing , examine the print carefully to see that the worked - up areas are clear . If any stains remain , soak the print for five minutes in a 5 % sodium bisulfite solution . It can be made up as follows :
Water - - - 32 ounces
Sodium bisulfite - - - 1½ ounces
If sodium bisulfite is not available , potassium metabisulfite , although it costs a little more , will work as well . This treatment will usually clear up yellow ferricyanide stains .
التقنيات المهنية المتقدمة ..
تحسين الطباعة ..
التخفيض المحلي للمطبوعات الجافة
تقليل البقع للطباعة
LOCAL REDUCTION OF DRY PRINTS
You can re - soak dried prints in hypo and reduce them with ferricyanide alone , using the technique just given . However , there is much less likelihood of stain if the print is soaked in plain water and the combined hypo - ferricyanide solution used .
First soak the prints until they are thoroughly limp . After they are properly soaked and not before , prepare the reducing solution . Since Farmer's reducer keeps only a few minutes after mixing , it should not be prepared until you are ready to start using it . The following proportions of the formula given earlier in this Assignment are recommended :
25 % hypo solution - - 1 ounce
10 % ferricyanide solution - - 1/4 ounce
Water - - 6 ounces
This is a fast working solution , so you may find it easier to use half the quantity of ferricyanide ( or double the water if you do not have an accurate small graduate ) .
Place the wet print face up on the flat surface and wipe off all the surplus water with a soft rubber squeegee . Dip a small swab of cotton into the reducer , squeeze out the surplus to prevent dripping and apply it to the print . From here on you use exactly the same technique as outlined in detail in the preceding pages - except that you omit the hypo soak at intervals . Instead , wash out the reducer thoroughly , using lots of water and a large dripping swab of cotton , or better still , play hose on the print if you can . After reduction is complete , fix and wash thoroughly in the usual way .
SPOT REDUCTION OF THE PRINT
Up to now we have been dealing with wet prints and for a very good reason . We have been concerned with reducing either the entire print or poorly defined areas . The water in the emulsion was needed to allow good diffusion of the reducer so that it would act uniformly over the area worked on and diffuse out imperceptibly from it , thus avoiding sharp tell - tale lines between these areas and the rest of the print .
There are times , however , when we do not want to diffuse edges at the spotting zones . For example , a black spot in the sky caused by a clear speck in the negative must be cleanly removed - there must be no perceptible diffusion of the reduced zone . Fine telephone lines running across a landscape present a similar problem . For such work a minimum of diffusion and a maximum of accuracy and sharpness are necessary - and for such work the minimum amount of water must be used . This means a dry print and minute amounts of very concentrated solutions .
For spot reduction you need concentrated Farmer's reducer , two small pieces of clean white blotter , two spotting brushes ( No. 0 and No. 3 ) , plenty of good light and , of course , the print .
With everything in readiness , mix the hypo and ferricyanide . Because it will be applied to the print in very small quantities with a brush that is barely moist , the reducer may be used full strength , one part of the hypo solution to two parts of the ferricyanide solution . If you don't have a small graduate , measure out the required quantity of each stock solution you want with a medicine dropper . Dip your spotting brush into the reducer and take off the excess on the side of the graduate . The brush is still much too wet , so dry it by drawing it across one of the blotters with a slight rotary motion . This motion will cause the brush hairs to come to a fine poin thus permitting you apply the reducer to the print exactly where you want it without fear of spreading . ( See Figure 17 ) You should wipe the brush on the blotter this way until it is almost dry . The idea is to use such a small amount of solution that when it is applied to the print there is not enough water to penetrate deeply or to diffuse beyond the actual line of contact between the brush and paper .
Figure 17 Removing black spots with concentrated - ferricyanide solution .
Hold the brush almost vertically over the spot you want to remove . If the spot is elongated , draw the brush along the spot in the direction of its maximum length if the spot is round , work the brush in a circle , taking care to cover its entire surface . Do not press downward ; it is the chemical action and not the friction that does the work . Keep the area of contact between the brush and paper as small as possible , because that is the only way you can do accurate work .
In a little while , the reducer will begin to take hold and you will see the spot beginning to lighten . When it is still a trifle darker than the surrounding area , blot it carefully with a clean blotter to pick up the reducer , and go on to the next step .
It is best to stop just short of the right point . If you have not dried your brush sufficiently , the emulsion will take up so much reducer that it will not be entirely exhausted by the silver going into solution , and so the action will continue even after you have blotted the surface solution off the print .
After you have worked on the second spot , you can go back to the first again and look at it carefully . If it is still too dark , apply more reducer little by little until the spot disappears .
When you are through spot - reducing a print , wash it for ten minutes to remove the ferricyanide and then fix it for at least five minutes in fresh hypo solution . Your regular acid hypo can be used - provided it is fresh - but you will run into less staining complications if you use a fresh non - acid fixing solution made by dissolving about 8 ounces of hypo in a quart of water . The strength of the solution is not critical , so you can simply measure out 8 ounces of crystal hypo , by volume , in a graduate instead of weighing it .
After reduction is complete , wash and dry the print in the usual way . However , before washing , examine the print carefully to see that the worked - up areas are clear . If any stains remain , soak the print for five minutes in a 5 % sodium bisulfite solution . It can be made up as follows :
Water - - - 32 ounces
Sodium bisulfite - - - 1½ ounces
If sodium bisulfite is not available , potassium metabisulfite , although it costs a little more , will work as well . This treatment will usually clear up yellow ferricyanide stains .
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