i got a heating pad, ill use it next time. But i guess it will only go up to maybe 36°C.
I thaught the last alcohol bath was supposed to be hot. And boiling seemed the hottest i could go
the fumes where not that bad, they were intense yes, got me boozed up a little. Made the bad results less painful.
next time ill bake for 3 min and i will dramaticaly reduce the distance between colimating lense and object. That should put much more energy on the gelatin during exposure.
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I found some very useful adive from the past topics i did not find in the wiki ( or maybe i was just blind
):
Dave: 100mw of green light is not really that powerful when it comes to dcg holography.
JohnFP:
In fact 90 seconds with 100mW is enough for a 4x5 plate with regular DCG. As long as your beam spread is just past the 5" mark (6 or so inches). I think I was down to 5 to 20uJ/cm^2. You're up to about 60uJ/cm^2 using 6" spread, 10% loss and 90 seconds.
Michael if you remember we did a 4x5 with Danny's 150mW and the exposure was only 90 seconds (I think). The G307 is about 4 - 10 times more sensitive.
John Fp:
Then filter the gelatin through 2 coffee filters.
Sometime when you blow dry a hologram is starts to turn milky but if you continue, sometimes for minutes, the milkiness goes completely away. Just wondering if you stopped to soon to clear the center. Don't be affraid if the hologram turns milky upon initial blow drying and quit. Continue real close to plate, hot and heavy and see if it clears.
Well, milky means one thing for sure, not hardened enough. So the fix is simple and only has to be one of these if within their range; higher bloom, age film longer, longer exposure, more pre hardening, more post hardening, lower alcohol temps, longer bath in alcohols and slower concentration differences from one alcohol bath to another. So again, just tighten one at a time and work from there
MichealH:
They were exposed between 60 @ 210 mJ, fixed for 2 minutes in diluted fixer, rinsed for a couple of minutes and processed and re-processed a variety of ways. The one in the photo was processed once with 25/70/99% alcohol with the last bath at 124F, air dried and put on a hotplate for a couple of minutes.
Dave:
Simon ,go and get a few more granite tiles and keep them in the freezer .............then you have instant cooling across the plate, then your holos will stay brighter to the outer edges.
I liked using the hot and cold plate as the heating/cooling effect should be uniform across the plate, if not it will cause a differential in the shrinking or setting of the Bragg planes and cause the edges to reconstruct at a slightly different angle than the center. Making the edges of the hologram looking dim .I found this even drying to be very critical when making DCG proximity masters ...........
