Fixing and Washing

Many toning processes in photography involve the use of selenium compounds.6 One such process recently recommended consists in treating the print or lantern slide, after developing, fixing and washing, with a solution containing about 1 per cent, of crystalline sodium sulphide and 1 per cent, of sodium selenite or selenious acid after twenty minutes or so in such a bath intense brown tones are obtained with chlorobromide papers, or brown-violet tones with pure bromide papers.7... 

To use this method, expose, develop in a neutral tone developer, fix, and wash a print in the usual manner. Next, use Print Rehalogenating Bleach (Formulas Print Reducers Print Rehalogenating Bleach) to convert all silver metal to silver bromide. Then rinse for 5 minutes and redevelop using any toning developer of your choice (this includes cold-tone developers). 

While it is perfectly acceptable to tone prints that have just been fixed and washed the most consistent results are obtained from toning dry prints that have been re-wet for 5 minutes. This is because the emulsion of freshly processed prints is still in a state of flux. This instability may cause minor variations between prints, even within the same batch. If the prints are to be stored for extended periods prior to toning, use proper storage techniques, as you would for any fine print. Prints that have been stored in or around materials that off-gas may exhibit staining. 

Each toner/variation responds differently to different paper and developer combinations. For that reason, it is a good idea to make a swatch book for your toning experiments. This can be done using reject prints cut into strips. Ideally the print should be one that almost succeeded or perhaps a perfect print that has been damaged at some point. In any event they should be neither too dark nor too light and contain a full range of tones. Fix and wash these prints as you would any other and save them to make toner test strips. 

Even a properly fixed and washed print will form silver sulfide as a result of atmospheric pollutants, such as sulfur dioxide. Unless controlled, these sulfide compounds will occur in a haphazard manner that will eventually degrade or destroy the print. 

When all black spots have been removed, catch lights added, and satisfaction achieved, rinse, fix, and wash. This must be done for even the smallest spot, otherwise the color of the print will eventually change. 

After development the film should be rinsed in stop bath or a plain running-water bath and then fixed and washed in the usual manner. 

Bleach to completion. Wash thoroughly until the yellow stain has disappeared. The removal of yellow stain is accelerated if after a 2 to 3 minute wash the negative is immersed in a 2% solution of sodium bisulfite for a few minutes and then returned to the wash. Redevelop in a slow-acting developer, such as D-23 diluted 1 5, then fix and wash in the usual manner. 

Bleach the negative in this solution and after thorough washing redevelop to desired density in negative developer Ansco 47. Then fix and wash in the usual manner. Conduct the operation in subdued light. 

Develop, fix, and wash a print in the usual manner. Use a neutral tone developer such as Kodak D-72. 

Fig. 12.7. Time course of [3H]thymidine incorporation into DNA of UV irradiated, hydroxyurea-treated lymphocytes. 3 X106 lymphocytes from actinic keratosis patients ( ) or age-matched normal individuals (o) were incubated with [3H]thymidine (5/iCi/ml, 18.5 Ci/mmol) and hydroxyurea (1.5 mM) at 37°C immediately after irradiation (20 J-m 2). After incubating for different times cells were fixed in Camoy s fixative and washed with 5% trichloracetic acid and ethanol before counting. (Reproduced from Abo-Darub et al., 1978, with kind permission of the authors and...

The resulting cell pellets are resuspended, fixed and washed in 70% (v/v) methanol for 5 min. The methanol in addition to fixing the cells removes any unreduced NBT which may have adsorbed onto the plastic. This is important as residual NBT can react with the potassium hydroxide in the next step and produce additional blue colouration. 

Although fixing and washing are not usually considered as electron transfer reactions, they are important parts of photographic processing as they confer stability to the processed material and will be discussed briefly. 

The film is fixed and washed. The negative is dark where Ag ions have (5 Light projected through the negative is... 

Remove fixative and wash twice (1 min each) with 400-fxl per well (each time) of MSM-Pipes. 

Surf Clam. Longo et al. (1994) have examined the Spisula lamin L67 in male pronuclei assembled in vitro. Nuclei are fixed in 3% paraformaldehyde in PBS for 1 hr and washed in PBS as described earlier. Fixed and washed nuclei are applied to a poly(L-lysine)-coated cover slip. Nuclei are reacted for 30 min with a 1 100 dilution of the anti-Spisula L67 Pab227 antibody. Cover slips are washed extensively in PBS, incubated for 30 min in a 1 20 dilution of FITC-conjugated antirabbit antibody, washed in PBS, and mounted in glycerol. 

Remove the culture medium by aspiration and add 2 ml PBS per well to wells that contain a cover slip. Incubate for 1 min at room temperature and wash once more with 2 ml PBS. Aspire all liquid, add 1 ml freshly prepared fixative, and incubate 15 min at room temperature. Remove the fixative and wash three times for 1 min with 2 ml PBS. To reduce autofiuorescence, incubate the cover slips after fixation in 2 ml freshly prepared NaBHi solution and incubate 5 min at room temperature. Remove the solution and add another 2 ml NaBH4 solution and incubate again 5 min. Next, wash two time for 1 min with 2 ml PBS. Cover slips with fixed cells can be stored in PBS at 4°C. Add a preservative to prevent bacterial and fungal growth. Do not allow the cover slips to dry. 

Centrifuge the cells at ca 250g for 10 mm to remove the fixative and wash the cells with PBS. 

Pour off fix and wash three times with PBS by flooding the slide with approximately 2 ml of PBS and then pouring it off Again, be gentle when adding each wash solution or the cells may be washed off the slide. 

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