Search found 165 matches

by jrburns47
Tue Feb 15, 2022 9:47 pm
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 60560

Re: Reuse of Pyrogallol developer

92F4BEE3-4BE4-4340-ACF1-371FEB477897.jpeg Back with an update: Photo is the second HRT BB640 test plate. The first had absolutely nothing on it because all four exposures were way too short. I HATE squeegees! I haven’t mastered the technique yet obviously. There’s got to be a better way. I squeegee...
by jrburns47
Wed Jan 26, 2022 10:38 am
Forum: General Holography
Topic: Rejuvenating old Ilford plates
Replies: 29
Views: 26146

Re: Rejuvenating old Ilford plates

Meter is reading in mw & uw. I know that as a theorist you don’t like ergs as an expression of power. Regardless, it’s reasonable to say that 10 ergs=1 microwatt (uw). Ergs were a useful thing when 3mw HeNes were teaching lasers.
by jrburns47
Wed Jan 26, 2022 12:22 am
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 60560

Re: Reuse of Pyrogallol developer

After a lot of back and forth about the total non exposure response I’ve been experiencing with old (30+ years?) Ilford red sensitive SP696T plates, I think I’ve found the problem. It doesn’t appear to be fogging or dark reaction per se but seems to be gross insensitivity. Without presensitizing it ...
by jrburns47
Wed Jan 26, 2022 12:19 am
Forum: General Holography
Topic: Rejuvenating old Ilford plates
Replies: 29
Views: 26146

Re: Rejuvenating old Ilford plates

After a lot of back and forth about the total non exposure response I’ve been experiencing with old (30+ years?) Ilford red sensitive SP696T plates, I think I’ve found the problem. It doesn’t appear to be fogging or dark reaction per se but seems to be gross insensitivity. Without presensitizing it ...
by jrburns47
Sun Jan 23, 2022 2:58 pm
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 60560

Re: Reuse of Pyrogallol developer

Two questions: - is there a meaningful study, or other information, discussing how much of a sensitivity increase occurs with a TEA pre-soak, and what percentage of solution is best for different silver halide emulsions? My assumption is that Colour Holographics must have done a fair amount of study...
by jrburns47
Sun Jan 23, 2022 2:06 pm
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 60560

Re: Reuse of Pyrogallol developer

Again, for those who might be interested, here’s an annotated photo of first successful “quadrant” exposure test 022-02-2022 on 4x5” 8E75HD. The total power at plate was ~25mw 660nm w/ an avg. 4:1 beam ratio, open aperture achromat H2 transfer from a ruby pulse 12x16” portrait master both RB & O...
by jrburns47
Sun Jan 23, 2022 1:13 pm
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 60560

Re: Reuse of Pyrogallol developer

For those who might be interested, here’s a corrected & reannotated photo of first successful “quadrant” exposure test 014-02-2022 (Julian date, exposure # that day, year) on 4x5” 10E75NAH. The total power at plate was ~35mw 660nm w/ an avg. 7:1 beam ratio, open aperture achromat H2 transfer fro...
by jrburns47
Sun Jan 23, 2022 10:54 am
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 60560

Re: Reuse of Pyrogallol developer

No I haven’t been squeegeeing the plates after photoflo. Always having been a white light transmission holographer, I missed out on that whole squeegee thing. I have them now and guess I’ll have to “bite the bullet” and learn the technique, especially since ATF has jacked up the price of ethanol by ...
by jrburns47
Sun Jan 23, 2022 10:08 am
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 60560

Re: Reuse of Pyrogallol developer

Thanks Bob. Yes, I always read the beams perpendicular to direction of propagation and add the result and calculate ratio based on those readings. I seem to remember that, as the angle of the reference beam increases, the actual light entering the emulsion decreases since more is reflected from the ...
by jrburns47
Sun Jan 23, 2022 9:52 am
Forum: AgX
Topic: Reuse of Pyrogallol developer
Replies: 46
Views: 60560

Re: Reuse of Pyrogallol developer

Thanks Petr. Glad I’m not losing my mind! (Yet😂)… Although I’ve gotten decent results on very old 10E75 (35-40 years old) and on 8E75HD expiration date 6/2001), I had been completely unable to get any exposure at all on old (25-30 years old) Ilford SP696T - just an all over even emulsion coloration ...