b. EP 2 Parameter to be Monitored.
For the EP 2 process, there are
four parameters monitored: BR-HDC, HD-LD, LD, and D-MIN.
(1) BR-HDC. The top area on the Y-55 form is labeled for monitoring
both retained silver and leuco cyan dye. Plots higher than the aim density
represent retained silver. Plots lower than the aim density indicate leuco
cyan dye.
(2) HD-LD. The next control area down on the Y-55 is used to measure
contrast, which is HD-LD.
(3) LD.
The next control area down on the form is used to monitor
speed, which is LD.
(4) D-MIN. The bottom control area on the form monitors D-MIN, which
is the stain parameter.
c. Developer Solution Variables.
Several factors can cause abnormal
plots. Some of them are time and temperature, agitation, replenishment, and
(1) Time and temperature.
Plots resulting from variations in time
and temperature look very similar. Increased development time and/or high
temperature results in an increase in dye density. This appears in LD and
HD-LD parameters as a higher plot.
Low temperature and/or shortened
developer time results in a decrease in LD and HD-LD parameters.
(2) Agitation.
Higher agitation in the developer does not usually
result in abnormal plots. However, extreme agitation can cause oxidation.
Plots for low agitation resemble the plots for low temperature and short
developer time.
(3) Replenishment. A decrease in the replenishment rate results in a
decrease of dye formed; an increase results in an increase of dye formed.
These changes in dye formation cause changes in both the LD and HD
parameters.
(a) Too little replenisher or too much "starter" when mixing
working strength solution results in low plots for LD and HD-LD. Too much
replenisher or too little starter results in high plots.
(b) Recommended storage temperature for the developer replenisher
solution is 60 to 80 degrees F. Higher temperatures can increase oxidation
that will shorten the keeping time.
Excessive low temperatures may cause
the chemicals to precipitate.
3-15
SS0514
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