My experience is that it works with with fiber paper test strips. It will not work with RC paper. I use 1 minute and 80% full power. A rinse of about 1 minute before microwaving is necessary. Otherwise, the color will be different.Anupam Basu said:Well, ok - not prints, but test strips. Does anyone do this? A search turned up the heartening fact that Ansel Adams did, so I am looking for any tips - how much power, how long etc. Is the effect different than normal drying? Crucially, is the drydown factor exactly the same?
I am thinking of doing this especially with fiber paper test strips.
Thanks,
-A
What are production prints?blaughn said:recommended for production prints.
What change are you talking about? How do you know that it takes place?Photo Engineer said:The environment around the silver filaments in the print is changed on a micro scale during microwaving. This has a subtle effect on the tone as noted above. IDK how bad or good it is, but I know it takes place.
PE
PeterB said:What change are you talking about? How do you know that it takes place?
For microwaves to actually induce an electric field (AC current) in the silver metal, the length of the metal should be optimally 1/4 the wavelength of the microwaves (approx 12cm/4=3cm). The dimensions of any 'continuous' length of silver metal in the photo paper is much less than this. In fact the individual and unconnected silver halide crystals which then develop to form filamentary silver are tiny.
regards
Peter
It is the two dimensional 'length' of the filament that is important here. As an example, if I take a telescopic FM radio antenna say 1m long (assume it is very thin for the sake of discussion), and crumple the antenna up into a small cube with a side of only 1mm, then the antenna will be useless if we want it to receive the intended FM radio waves.Photo Engineer said:Peter, although an individual silver halide crystal in a B&W paper may be small, on the order of 0.2microns on a side assuming a cube of AgCl, the filament that is formed may indeed be quite long. This is assuming filimentary silver formation during development as opposed to tabular.
Technically it doesn't rule it out, but the current's magnitude will be SO small as to probably be but a few more electrons above the noise floor ! I could go and look up the maths, but we'd be talking pico, no, maybe femto-amps for sure!Photo Engineer said:But, as you say, the operative word is 'optimally' meaning that the highest statistical probability is if the wavelength is as you say, but that does not rule out induced current in shorter or longer filaments. (does it?)
'shorter' doesn't really make sense here. I assume that the filament length (if stretched out) will still be much shorter than 3cm (=1/4 of the microwave's wavelength). OTOH, if you meant there are sufficiently different length microwaves in the oven to be significant at the filament's length, then that isn't the case.Photo Engineer said:There are ample photomicrographs of the filaments that form in the literature that I don't feel I have to post one here, but I do believe that they can approach a considerable length, but whether they can react with the shorter wave microwaves IDK. I doubt that anyone has 'unravelled' one of the filaments that form to actually measure its length.
I think the relevance of this latter point supports my notion that it is the water that is heating things up and not the silver.Photo Engineer said:Not even color products which contain no silver when finally processed. (This latter was interesting as I thought of it while writing this reply)
Quite possibly localised heating could cause this, the object would need non-symmetrical or 'pointy' sections on it for this to happen. This is the case with the corners of the paper.Photo Engineer said:It may just be that it has nothing to do with the silver itself, but rather a vesicular effect from the micro bubbles formed if you boil water in your wet print causing some sort of translucency. There are many imponderables here that were brought to my attention those many years ago by some very respected fellow engineers with years of experience.
My guess is that this is resulting from a weak dielectric heating effect.Photo Engineer said:An added comment. IIRC, it was shown somewhere that microwaving unprocessed photo products had an effect on the latent image. If true, I wonder why?
B&Wenthusiast said:lay the prints out between pages of phone books for a couple of minutes -- the paper absorbs the water quickly and doesn't do anything to the prints!
A good use for recycled phone books, also!
PE, the only explanation I can give is that there are some chemicals containing polar molecules which remain around the silver after development. As per my previous post, polar molecules do heat up in a microwave and this possibly causes the paper/emulsion to swell. Not being a chemist I haven't really taken a big interest (yet) in all the possible chemicals and reactions that go on in the paper which could contribute to concentrations of a particular substance (besides silver metal) forming around the image. Maybe there is no such thing, in which case I have no explanation for what you remember.Photo Engineer said:Thinking back on this last evening, I seem to remember a demonstration of microwaving a step wedge of a B&W material and showing a thickness difference and an imagewise change in tone as a function of step. It was as if the image swelled as a function of the amount of silver and changed in tone quality. That is why I relate, in my mind, the effect of microwave on silver, but perhaps it is due to another effect.
...
If it were due to water alone, I would expect this effect to be an even distribution, but I am pretty clear in my memory that the effect was imagewise and the comments here seem to indicate some weak correllation as well with an imagewise change. Any thoughts?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?