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التقنيات المهنية المتقدمة ..
تحسين الطباعة ..
تقنية التخفيض ..
REDUCTION TECHNIQUE
A print may be reduced any time after it is made . The most convenient time . is just after development while it is still in the hypo , but unless you have made prints from the same negative before and are absolutely certain how the dried print will look , it is much safer to dry the print first . You can then study it at your leisure , and you will not be misled by the change in density and contrast due to drying . Since you may want to reduce prints either before or after drying , both techniques will be fully discussed .
Although many reducing formulas have been published , plain hypo ferricyanide ( Farmer's reducer ) is still by far the most popular . It is cheap , very ! easy to use , and gives excellent results . It has only one serious drawback - an inclination to stain . However , if it is properly used , its staining tendencies can be kept in check without too much difficulty .
So frequent is the use of ferricyanide for lightening prints that the term ferricyaniding has become common usage among photographers . We will use it here for that reason .
If a print is to be ferricyanided while it is still in the hypo , the procedure is extremely simple . You need only a 10 % potassium ferricyanide solution , a flat rubber squeegee , and a sheet of plate glass a little larger than the print . If you do not have the plate glass , use the bottom of a clean enameled tray , provided the enamel is not chipped or cracked . To prepare a 10 % ferricyanide solution , simply dissolve 1 oz . of potassium ferricyanide in about 8 oz . of water and then add enough water to bring the total volume to 10 oz .
This stock solution is much too strong for direct use you must dilute it quite a bit to slow down its reducing action to the point where you can control it . The exact strength of the working solution depends largely upon the type of paper used . Ferricyanide works much more rapidly on warm toned papers than on cold toned papers . The dilutions given below are , therefore , to be used only as a starting point .
One - half ounce of stock to 50 ounces of water is about right to start with , but if you have had very little photographic experience and want more time to judge the progress of the reducer , one quarter ounce of ferricyanide stock to 50 ounces of water would be safer . If the paper you use is reduced too rapidly to permit good control , use half the amount of ferricyanide ; if on the other hand , action is too slow , use half the amount of water .
To prevent over - fixing , which will greatly retard subsequent washing , it is advisable to ferricyanide a print within a few minutes after it has been put into the hypo - certainly not more than five minutes . If you allow the print to remain in the hypo solution for an hour or two while you do all your printing first , the paper will absorb so much hypo that it will require hours of washing . If you can't do your reducing right away , fix the print for the normal time and transfer it to a tray of running water until you are ready to reduce it .
If you intend reducing several prints , start on one of the denser ones first . Ferricyanide solution works very quickly when fresh , but slows up markedly in a short time . You will find it a lot safer to reduce the denser prints with a fresh and quick - acting solution at the start and reserve the lighter prints for the end when the solution works more slowly . Figure 11 shows the layout of trays for ferricyaniding a print overall . The left - hand tray contains the prints in the hypo .
Pick up the print to be reduced and let most of the hypo drain back into the tray . Now place it on a sheet of plate glass or the bottom of a clean tray and with a rubber squeegee wipe off all surface hypo from both sides of the print . ( Figure 12 ) The hypo in the print itself is all that is necessary - any surplus merely neutralizes the ferricyanide , slows up reduction and increases the tendency to stain .
Figure 11 Layout of trays for reducing hypo - laden prints .
Figure 12 Squeegeeing excess hypo from prints .
Immerse the print quickly in the diluted ferricyanide solution and start rocking the tray immediately . Reduction will begin at once , so that quick work is absolutely essential at this point . If only a slight amount of reduction is required , lift the print out of the solution in five to ten seconds and allow it to drain . Watch the highlights carefully , because reduction will be very rapid there . As soon as you begin to notice any appreciable lightening of the highlights , throw the print quickly into the wash water and agitate it thoroughly for a minute or two to wash out most of the ferricyanide and stop further reduction .
After this quick rinse , put the print back into the hypo to complete the fixing . If reduction has not gone far enough , let the print soak in the hypo for a minute or two and repeat the ferricyanide treatment . The ferricyanide solution can be used a number of times this way before it is exhausted and stops working . To replenish it , add about half the original quantity of stock solution . If necessary , you can repeat the replenishing procedure as long as the color remains a lemon yellow . When it becomes noticeably tinged with blue or green , throw it away and mix a fresh batch ; a discolored ferricyanide bath will stain your prints .
To reduce prints successfully , you must work fast , and you must not try to take off too much silver at one time . It is much safer and better to put a print through the ferricyanide three times , reducing it just a little each time , than to try to do all of it in one step . Ferricyanide works very quickly and is not stopped immediately by rinsing . If your solution is so strong that you can actually see it biting into the image , it is too strong to be controlled . It will keep right on working after the print is transferred to the water and won't stop until the ferricyanide has had time to diffuse out of the emulsion . By then the highlights . will have been eaten away and the print ruined .
You will find it much safer to work with a dilute ferricyanide solution , not only because you can control its action , but because concentrated solutions used with acid hardener hypo may stain if allowed to act on a print for too long . To avoid stain , use a weaker solution and reduce the print by easy stages .
After you have attained some degree of skill , it is possible to do a certain amount of selective reduction . For example , if one corner is a little too dark , it is a simple matter to lower the print slowly into the ferricyanide , dark corner first , and remove it slowly , dark corner last . This will allow the ferricyanide to work for a longer period on the darkened corner , thus biting into it more than the rest of the print . If only the middle needs pepping up , you can see - saw the print up and back in the ferricyanide for a short time without immersing the top and bottom at all . ( Figure 13 ) Such work calls for extreme care , but see - sawing the print a number of times , stopping at a different point each time will generally prevent an obvious line between the reduced and unreduced areas . For more localized work , you had better apply the ferricyanide exactly where you want it with a brush or dab of cotton as explained later .
The method of ferricyaniding we have discussed above is the most convenient for prints that have just been made and haven't yet been washed or dried . If you find it necessary to reduce a print after it has been dried , you can soak it in hypo for about five minutes or until it is quite limp and then proceed to reduce it exactly as you would a freshly made print . This is a method commonly used by photographers who seldom have occasion to reduce prints after they are dried .
Figure 13 Partial ferricyaniding of a print .
A somewhat better method of reducing dried prints is to use a complete hypo - ferricyanide reducer . It increases contrast slightly more than the first method , and s less likely to stain .
Farmer's reducer for prints should be made up as two separate stock solutions , a 10 % potassium ferricyanide solution as described above , and a 25 % hypo solution which can be made by dissolving 8 oz . of hypo crystals in 32 oz . of water . The strength of the hypo solution is far from critical , so that if you don't have a suitable scale , measure the hypo by volume . 8 oz . by volume of small hypo crystals will generally weigh a little less than 8 oz . , but this is close enough . Both solutions will keep separately for months under average conditions . When mixed , they react together so that the reducer becomes ineffective in from five to fifteen minutes , depending upon the strength . For that reason , never mix the hypo and ferricyanide until the very last minute . The recommended proportions for average . work are :
25 % hypo solution 6 ounces .
10 % ferricyanide solution . ½ ounce
Water 50 ounces .
This working solution will permit fairly fast action , but not too fast if you are careful . At first you had better use about half the normal quantity of ferricyanide solution to slow up reduction until you know how to handle the standard strength safely .
First , let the print soak thoroughly in plain water until it is quite limp . When it is ready , pick it up by the corner , let it drain , and slide it quickly into the reducer .
Note the time carefully and start rocking the tray vigorously . If the print is light and you want very little reduction , pull it out quickly in five seconds without taking time to look at it and slide it into the wash tray . If the print is quite dense , ten seconds reduction may be better . As soon as the print hits the water , start agitating it and keep it moving briskly for at least a minute to wash out the reducer before you take it out to examine it carefully .
Note the highlights particularly . The first sign of over reduction shows up in blank patches of clear paper with very grainy edges . Always stop before this stage is reached , even if the print is too dark in other areas . You can always reduce such darker zones later by local reduction , as explained in the following pages , but you cannot replace a highlight after you've dissolved it away .
If the reduced print is still too dark , put it through the reducer once more . Repeat as often as is necessary to give you the desired result , but keep the following precautions in mind . Don't try to dissolve too much silver at once or the print will stain . Take a little at a time and wash the ferricyanide out thoroughly each time if you want a clear print with no trace of blue or yellow in the highlights . Don't try to watch the progress of the reducer with the idea of stopping its action when the print is right . In the first place , the gradual lightening of a print is almost impossible to see until it has gone too far , and in the second place , reduction will continue for an appreciable length of time after the print is removed from the reducer , since at least a minute is needed for the ferricyanide to diffuse out of the gelatin to the point where it is too weak to act further .
After you reduce a print the right amount , always wash it for five minutes to take out most of the ferricyanide solution . Then fix it again for five minutes in a fresh hypo solution and wash well for at least an hour . It is common practice to fix the reduced print without the intermediate wash , but this may give you a stained print if it has soaked up a lot of ferricyanide and the fixing bath is an old one .
التقنيات المهنية المتقدمة ..
تحسين الطباعة ..
تقنية التخفيض ..
REDUCTION TECHNIQUE
A print may be reduced any time after it is made . The most convenient time . is just after development while it is still in the hypo , but unless you have made prints from the same negative before and are absolutely certain how the dried print will look , it is much safer to dry the print first . You can then study it at your leisure , and you will not be misled by the change in density and contrast due to drying . Since you may want to reduce prints either before or after drying , both techniques will be fully discussed .
Although many reducing formulas have been published , plain hypo ferricyanide ( Farmer's reducer ) is still by far the most popular . It is cheap , very ! easy to use , and gives excellent results . It has only one serious drawback - an inclination to stain . However , if it is properly used , its staining tendencies can be kept in check without too much difficulty .
So frequent is the use of ferricyanide for lightening prints that the term ferricyaniding has become common usage among photographers . We will use it here for that reason .
If a print is to be ferricyanided while it is still in the hypo , the procedure is extremely simple . You need only a 10 % potassium ferricyanide solution , a flat rubber squeegee , and a sheet of plate glass a little larger than the print . If you do not have the plate glass , use the bottom of a clean enameled tray , provided the enamel is not chipped or cracked . To prepare a 10 % ferricyanide solution , simply dissolve 1 oz . of potassium ferricyanide in about 8 oz . of water and then add enough water to bring the total volume to 10 oz .
This stock solution is much too strong for direct use you must dilute it quite a bit to slow down its reducing action to the point where you can control it . The exact strength of the working solution depends largely upon the type of paper used . Ferricyanide works much more rapidly on warm toned papers than on cold toned papers . The dilutions given below are , therefore , to be used only as a starting point .
One - half ounce of stock to 50 ounces of water is about right to start with , but if you have had very little photographic experience and want more time to judge the progress of the reducer , one quarter ounce of ferricyanide stock to 50 ounces of water would be safer . If the paper you use is reduced too rapidly to permit good control , use half the amount of ferricyanide ; if on the other hand , action is too slow , use half the amount of water .
To prevent over - fixing , which will greatly retard subsequent washing , it is advisable to ferricyanide a print within a few minutes after it has been put into the hypo - certainly not more than five minutes . If you allow the print to remain in the hypo solution for an hour or two while you do all your printing first , the paper will absorb so much hypo that it will require hours of washing . If you can't do your reducing right away , fix the print for the normal time and transfer it to a tray of running water until you are ready to reduce it .
If you intend reducing several prints , start on one of the denser ones first . Ferricyanide solution works very quickly when fresh , but slows up markedly in a short time . You will find it a lot safer to reduce the denser prints with a fresh and quick - acting solution at the start and reserve the lighter prints for the end when the solution works more slowly . Figure 11 shows the layout of trays for ferricyaniding a print overall . The left - hand tray contains the prints in the hypo .
Pick up the print to be reduced and let most of the hypo drain back into the tray . Now place it on a sheet of plate glass or the bottom of a clean tray and with a rubber squeegee wipe off all surface hypo from both sides of the print . ( Figure 12 ) The hypo in the print itself is all that is necessary - any surplus merely neutralizes the ferricyanide , slows up reduction and increases the tendency to stain .
Figure 11 Layout of trays for reducing hypo - laden prints .
Figure 12 Squeegeeing excess hypo from prints .
Immerse the print quickly in the diluted ferricyanide solution and start rocking the tray immediately . Reduction will begin at once , so that quick work is absolutely essential at this point . If only a slight amount of reduction is required , lift the print out of the solution in five to ten seconds and allow it to drain . Watch the highlights carefully , because reduction will be very rapid there . As soon as you begin to notice any appreciable lightening of the highlights , throw the print quickly into the wash water and agitate it thoroughly for a minute or two to wash out most of the ferricyanide and stop further reduction .
After this quick rinse , put the print back into the hypo to complete the fixing . If reduction has not gone far enough , let the print soak in the hypo for a minute or two and repeat the ferricyanide treatment . The ferricyanide solution can be used a number of times this way before it is exhausted and stops working . To replenish it , add about half the original quantity of stock solution . If necessary , you can repeat the replenishing procedure as long as the color remains a lemon yellow . When it becomes noticeably tinged with blue or green , throw it away and mix a fresh batch ; a discolored ferricyanide bath will stain your prints .
To reduce prints successfully , you must work fast , and you must not try to take off too much silver at one time . It is much safer and better to put a print through the ferricyanide three times , reducing it just a little each time , than to try to do all of it in one step . Ferricyanide works very quickly and is not stopped immediately by rinsing . If your solution is so strong that you can actually see it biting into the image , it is too strong to be controlled . It will keep right on working after the print is transferred to the water and won't stop until the ferricyanide has had time to diffuse out of the emulsion . By then the highlights . will have been eaten away and the print ruined .
You will find it much safer to work with a dilute ferricyanide solution , not only because you can control its action , but because concentrated solutions used with acid hardener hypo may stain if allowed to act on a print for too long . To avoid stain , use a weaker solution and reduce the print by easy stages .
After you have attained some degree of skill , it is possible to do a certain amount of selective reduction . For example , if one corner is a little too dark , it is a simple matter to lower the print slowly into the ferricyanide , dark corner first , and remove it slowly , dark corner last . This will allow the ferricyanide to work for a longer period on the darkened corner , thus biting into it more than the rest of the print . If only the middle needs pepping up , you can see - saw the print up and back in the ferricyanide for a short time without immersing the top and bottom at all . ( Figure 13 ) Such work calls for extreme care , but see - sawing the print a number of times , stopping at a different point each time will generally prevent an obvious line between the reduced and unreduced areas . For more localized work , you had better apply the ferricyanide exactly where you want it with a brush or dab of cotton as explained later .
The method of ferricyaniding we have discussed above is the most convenient for prints that have just been made and haven't yet been washed or dried . If you find it necessary to reduce a print after it has been dried , you can soak it in hypo for about five minutes or until it is quite limp and then proceed to reduce it exactly as you would a freshly made print . This is a method commonly used by photographers who seldom have occasion to reduce prints after they are dried .
Figure 13 Partial ferricyaniding of a print .
A somewhat better method of reducing dried prints is to use a complete hypo - ferricyanide reducer . It increases contrast slightly more than the first method , and s less likely to stain .
Farmer's reducer for prints should be made up as two separate stock solutions , a 10 % potassium ferricyanide solution as described above , and a 25 % hypo solution which can be made by dissolving 8 oz . of hypo crystals in 32 oz . of water . The strength of the hypo solution is far from critical , so that if you don't have a suitable scale , measure the hypo by volume . 8 oz . by volume of small hypo crystals will generally weigh a little less than 8 oz . , but this is close enough . Both solutions will keep separately for months under average conditions . When mixed , they react together so that the reducer becomes ineffective in from five to fifteen minutes , depending upon the strength . For that reason , never mix the hypo and ferricyanide until the very last minute . The recommended proportions for average . work are :
25 % hypo solution 6 ounces .
10 % ferricyanide solution . ½ ounce
Water 50 ounces .
This working solution will permit fairly fast action , but not too fast if you are careful . At first you had better use about half the normal quantity of ferricyanide solution to slow up reduction until you know how to handle the standard strength safely .
First , let the print soak thoroughly in plain water until it is quite limp . When it is ready , pick it up by the corner , let it drain , and slide it quickly into the reducer .
Note the time carefully and start rocking the tray vigorously . If the print is light and you want very little reduction , pull it out quickly in five seconds without taking time to look at it and slide it into the wash tray . If the print is quite dense , ten seconds reduction may be better . As soon as the print hits the water , start agitating it and keep it moving briskly for at least a minute to wash out the reducer before you take it out to examine it carefully .
Note the highlights particularly . The first sign of over reduction shows up in blank patches of clear paper with very grainy edges . Always stop before this stage is reached , even if the print is too dark in other areas . You can always reduce such darker zones later by local reduction , as explained in the following pages , but you cannot replace a highlight after you've dissolved it away .
If the reduced print is still too dark , put it through the reducer once more . Repeat as often as is necessary to give you the desired result , but keep the following precautions in mind . Don't try to dissolve too much silver at once or the print will stain . Take a little at a time and wash the ferricyanide out thoroughly each time if you want a clear print with no trace of blue or yellow in the highlights . Don't try to watch the progress of the reducer with the idea of stopping its action when the print is right . In the first place , the gradual lightening of a print is almost impossible to see until it has gone too far , and in the second place , reduction will continue for an appreciable length of time after the print is removed from the reducer , since at least a minute is needed for the ferricyanide to diffuse out of the gelatin to the point where it is too weak to act further .
After you reduce a print the right amount , always wash it for five minutes to take out most of the ferricyanide solution . Then fix it again for five minutes in a fresh hypo solution and wash well for at least an hour . It is common practice to fix the reduced print without the intermediate wash , but this may give you a stained print if it has soaked up a lot of ferricyanide and the fixing bath is an old one .
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