PDA

View Full Version : HOME BREW 4X5 PLATES?



Pages : 1 2 [3]

knoxissimpler
02-20-2008, 10:18 PM
Thanks, I didn't know if the plastic would take the temp needed to melt the gelatin... I get to apply the coat in the morning, and check back in the afternoon (late) and the next day hopefully get results!... Since I can use plastic I decided that a double boiler would work... I plan to attempt to make an egg photographic (and for the rotting egg effect, I have stuff to take care of it... but it's kinda funny since I accidentally have turned on panoramic on my camera sometimes)... But just for the record, do you know if the copper will or will not react with the emulsion?

Photo Engineer
02-20-2008, 10:58 PM
What copper?

Copper is a no-no for emulsions unless added as a specific salt to a specific emulsion at a precise level.

PE

knoxissimpler
02-21-2008, 08:19 AM
what copper?

I was hoping to use a reverse condenser method (copper tubing with hot water running through it), but I figured (hence I asked) that it would displace the silver in this reaction
AgCl[aq] + Cu[s] --> CuCl[aq] + Ag[s]

Photo Engineer
02-21-2008, 10:19 AM
If silver salts contact copper tubing it is not good for the silver or the copper. If copper pipes are used in home plumbing, or even iron pipes, this generally presents no problem as long as the water is filtered.

PE

knoxissimpler
02-22-2008, 08:27 PM
I got to develop the first batch (since I was just developing, I was able to get some extra time by using the time slot of another class since no extra mess was made) and I couldn't even get the enlarger to expose one after a full minute, but the room lights do it in about four seconds... how much light do enlargers really put out?

Photo Engineer
02-22-2008, 08:31 PM
Not much and most enlargers have UV filters whereas room lights sometimes have some UV.

So, depending on the emulsion, your result is reasonable. Silver Chloride emulsions have very little visible sensitivity and that is why Azo paper is a contact chloride paper.

See post #6 and my others here for more details.

PE

knoxissimpler
02-22-2008, 08:45 PM
thanks, I know that at least one of the enlargers is like 20 years old, I might try that on a test strip, but I also have a little trick up my sleeve, Magnesium... I have been planning for a while to make my own enlarger and powering it by pure, burning magnesium ribbon... would basic magnifying lenses block UV? and is a UV filter in an enlarger removable? I don't have the resources for other emulsions, and I was hoping to transfer a prize winning image, could i do a contact print using a commercial photo paper print of the shot?

and also, could this emulsion be developed using a coffee developer? (just a thought, I am doing a LOT of projects in photography, mainly it has recently been centering on high speed photography and light paintings and controlled motion blurs, I, however, have been looking to expand my darkroom techniques)

Photo Engineer
02-22-2008, 09:46 PM
Well, magnesium burns hotter than most think and burns more quickly. That is why it was used as a flash powder at one time. I do not recommend it!

The chloride emulsion is at least 5 - 8 stops slower than enlarging emulsions and is sensitive in a different part of the spectrum by a reasonable amount. Also, many lenses are partially opaque to UV. I would use about ISO 1 in a camera. I've used it in bright sunlight and that would be about right. Coated on paper will roughly double the speed.

PE

knoxissimpler
02-22-2008, 09:57 PM
first, I'm not using it in a camera... yet, second, I have used magnesium before to expose images, just never in an enlarger (I mainly was thinking of it since it has a very high UV output [hence, its eye damaging powers] and I still would like to know if ordinary magnification glass would work (or if I really do need to get a special type of glass)
and also, would I be able to do the aforementioned contact print? I would hate to try without any basis first... I remember doing them with commercial photo paper a WHILE back, but have not tried on this emulsion... (you know, paper on paper under a light [in this case, a fluorescent bulb, but not multiples...])... and I am not using powders (or even a mixture of fuel and oxidizer) I am going really old school with this... magnesium RIBBON exposure... (back before the powder was used, I have seen units that had a roll of ribbon, and a chart of inches Vs time/exposure)

Photo Engineer
02-22-2008, 10:06 PM
Yes, but today's enlargers are not designed for this so don't set fire to your enlarger or darkroom.

IDK about the lenses but they will pass some UV. The only thing is to do it trial and error.

Sorry.

PE

knoxissimpler
02-22-2008, 10:30 PM
I guess I will have to just try some different lenses, and BTW, I am making a CUSTOM enlarger, that will contain the magnesium (it is designed for ONLY magnesium)... but this question, and the key question in my mind still remains, could I do a contact print to get the image (use regular enlarger to expose normal photo paper, then use developed paper to contact print onto new emulsion, which is on different materials)...

Photo Engineer
02-22-2008, 11:13 PM
With a normal enlarger, you cannot use a chloride emulsion such as I describe to make prints, due to speed. You will need straight tungsten light, an LF negative, and a contact printing frame. I print both contact prints on paper and glass slides.

PE

knoxissimpler
02-23-2008, 09:07 AM
Thank you, that is what I needed to know!