Search found 165 matches
- 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...
- 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.
- 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 ...
- 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 ...
- 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...
- 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...
- 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...
- 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 ...
- 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 ...
- 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 ...