Meeting 7

One print due at the beginning of class. Critique of work.

Spotting prints
Many darkroom prints show white spots where dust had settled on the negative during printing. Using retouching dye and a very fine brush are the traditional way to retouch the dust spots. Spotone used to be the brand employed by most photographers. It might not be available anymore. Spotone #3 was neutral tone but could be used on both warm and cold papers if the spot was small. When retouching large areas of a print, it becomes more important to match the retouching color with the print color.

What you'll need:

• Spotone #3 or other retouching dye
• Brush - small fine-tip brush (find a 000 or 0000 tip artist brush)
• Water - I use a few drops held in a film can lid
• Sheet of white paper or cardboard to soak up excess dye
• Your print to be retouched
   

The process is to lay out the print to be retouched on a clean surface, and array the other items conveniently nearby. Dip the tip of the brush into the dye, and dilute it by dipping next into the water. Usually you will have a large drop clinging to the brush tip, so dab it onto the sheet of white paper to absorb the excess. Check to see if the darkness of the dye is close to the area that you will be retouching. It's better to be a little lighter than to be too dark.

Apply the dye in a stippling (or "flyspeck") manner. Think about applying very small dots of film grain in the white area and you will get the idea. If you try to paint the surface, the ink will bleed onto adjacent areas causing a dark "halo".

If you manage to botch the retouching job, consider re-washing the print. Often the majority of dye will wash out and you can start again.

If you need to retouch large areas, you will need the appropriate dye color to match your printing paper.

Film curves and paper curves
Different films and papers have different "looks". A branch of photographic research deals with  the response curves of film and paper as a way to quantify the look. Here is a graph that compares Ilford Multigrade and Kodak Polymax using low contrast filters.

A densitometer is used to measure values for plotting. A flatbed scanner may be used with reasonable results instead. Use a calibrated Stouffer step wedge to convert the scanner values to density units.

Peculiarities of Ilford Multigrade contrast filters
I've found that the Ilford Multigrade filters appear to be mislabeled. I have two filter sets that exhibit the same irregularity, and did some experiments to dig a little deeper.

Experiment one:
I used a color analyzer to measure the relative amount of magenta and yellow light passing through the various filters in both Ilford Multigrade and Kodak Polymax filter sets. Here is a chart that compares the color passing through the two filter sets. This confirms what I see when I look at the filters and that I was not fooled by some neutral density added to equalize printing times.

Based upon the experiment above, use this progression of llford filters for increasing contrast...

00

0

1/2

1

1-1/2

2

4

2-1/2

3

4-1/2

3-1/2

5

Experiment two:
I did a lengthy investigation into the actual contrast that two papers produce using the two filter sets. The results are summarized in this chart.

Scardina portfolio