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#1
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Spots!
Hi,
I am plagued by spots on my B&W negatives: Many tiny spots which print put as white. They are much smaller than dust spots (on 8x10 inch prints they are about the size of pinpricks). Some frames have none and some have them all over the place (though they seem to group together and prefer the edges). What can they be? I’ve tried different films, developers, stops, fixers and even wetting agents with no difference. The local water has excellent drinking qualities and AFAIK no weird chemical or mineral content. The final rinse/wetting agent bath is in distilled water. Any ideas would be appreciated! Chris |
#2
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Spots!
In article ,
Chris Loffredo wrote: Hi, I am plagued by spots on my B&W negatives: Many tiny spots which print put as white. They are much smaller than dust spots (on 8x10 inch prints they are about the size of pinpricks). Some frames have none and some have them all over the place (though they seem to group together and prefer the edges). What can they be? I¹ve tried different films, developers, stops, fixers and even wetting agents with no difference. The local water has excellent drinking qualities and AFAIK no weird chemical or mineral content. The final rinse/wetting agent bath is in distilled water. Any ideas would be appreciated! Chris If the spots are dark its silver, maybe the problem is on the shutter curtain of your camera. If your using 4x5 holders it could be that the black has abraided and left small highly reflective areas that expose the film from the back side. This has happened to me on occasion I use a sharpie on my holders from time to time to recover the problem areas and make them black again. -- Baltimore & DC Large Format User Website http://members.verizon.net/~gregoryblank For best results expand this window at least 6" at 1152 x 768 resolution |
#3
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Spots!
In article ,
Chris Loffredo wrote: Hi, I am plagued by spots on my B&W negatives: Many tiny spots which print put as white. They are much smaller than dust spots (on 8x10 inch prints they are about the size of pinpricks). Some frames have none and some have them all over the place (though they seem to group together and prefer the edges). What can they be? I¹ve tried different films, developers, stops, fixers and even wetting agents with no difference. The local water has excellent drinking qualities and AFAIK no weird chemical or mineral content. The final rinse/wetting agent bath is in distilled water. Any ideas would be appreciated! Chris It could be that the distilled water you are using in your final rinse/wetting agent (distilled water) has minerals that upon drying are being left on the film surface. Although many would argue against it, try finding a high quality squeegee (you should inspect the edge with a loupe) and after using your wetting agent gently squeegee the excess water off the film by placing the film on a inclined glass surface. The most important thing here is to use a high quality squeegee. Dale www.dalestrousephoto.com |
#4
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Spots!
"Chris Loffredo" wrote
I am plagued by spots on my B&W negatives: Many tiny spots which print put as white. They are much smaller than dust spots (on 8x10 inch prints they are about the size of pinpricks). Some frames have none and some have them all over the place (though they seem to group together and prefer the edges). The local water has excellent drinking qualities and AFAIK no weird chemical or mineral content. Good drinking water can have a high mineral content and particle count. Well water, spring water and mountain run-off (esp. if it has glacial silt) are really dirty and mineral laden though good to drink ('long as there isn't a dead goat upstream). I would try using distilled water for -everything-; if you get spots it wasn't the water, if you stop getting spots keep using the distilled water. Since switching to distilled for film developing I have had _no_ problems with negative consistency. I used to blame all sorts of problems on my metering skills, the accuracy of my light meter the thermometer ... - and all the time it was the water. Any ideas would be appreciated! Advice worth price charged. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#5
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Spots!
Dale Strouse wrote:
It could be that the distilled water you are using in your final rinse/wetting agent (distilled water) has minerals that upon drying are being left on the film surface. How much mineral content could _distilled water_ have? -- .~. Jean-David Beyer Registered Linux User 85642. /V\ Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 07:30:00 up 4 days, 16:29, 5 users, load average: 4.21, 4.19, 4.13 |
#6
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Spots!
Jean-David Beyer wrote:
Dale Strouse wrote: It could be that the distilled water you are using in your final rinse/wetting agent (distilled water) has minerals that upon drying are being left on the film surface. How much mineral content could _distilled water_ have? Depends how it was handled and stored after distillation. Water can pick up sodium from glass, and ultrapure water will actually attack glass and etch it in much the same way strong hydroxide solutions can. If stored or transported in metal, the water may dissolve metallic oxides or hydroxides. If the distiller is overdriven (in an attempt to increase production rate) minerals may be carried over from the supply in droplets (as opposed to pure vapor transport from supply to collector). And, depending on the content of tap water used in earlier stages, a single rinse in distilled water may be insufficient to remove minerals deposited by the tap water. However, minerals in the water are are more likely culprit for water spots than for dirt specks, which are more likely to be particulates in the tap water than dissolved minerals, and which are unlikely to be adequately washed out with a single surfactant treatment using distilled water. My suggestion would be to do the entire wash step (as well as mix all chemicals) with distilled or commercially filtered water, using the Ilford water conservation method (fill, invert 5 times, drain; fill, invert 10 times, drain; fill, invert 20 times, drain, and you're done, according to Ilford, with water consumption only three times tank capacity), though I add a simple rinse before the inversion steps to remove gross quantities of fixer that might be trapped in the tank's light baffle or incompletely drained. Still, a quart of distilled water (four fills for a single 35 mm film in stainless) isn't too much to avoid introducing particles from tap water; I use drinking water filtered via reverse osmosis, which is particle free and costs only 39 cents per gallon as a refill to my containers; if I were processing in volume I'd most likely purchase an equivalent filter (submicron or reverse osmosis) for my home, specifically for use in film processing. Another advantage of distilled or filtered water -- stored with your chemicals, everything is at the same room temperature, and there's no concern about reticulation or fussing with the taps to adjust the water temperature -- just pour from the jug, and it's ready to go. -- I may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. |
#7
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Spots!
Chris Loffredo wrote:
Hi, I am plagued by spots on my B&W negatives: Many tiny spots which print put as white. They are much smaller than dust spots (on 8x10 inch prints they are about the size of pinpricks). Some frames have none and some have them all over the place (though they seem to group together and prefer the edges). What can they be? I’ve tried different films, developers, stops, fixers and even wetting agents with no difference. The local water has excellent drinking qualities and AFAIK no weird chemical or mineral content. The final rinse/wetting agent bath is in distilled water. Any ideas would be appreciated! Chris Thanks for the various comments. It is not a problem with the camera(s). Before I start using distilled water for everything (or risk more film experimenting), could it be the that I used the wetting agent in too high a concentration (didn't have any accurate measuring vessels on the order of 1cc)? Chris |
#8
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Spots!
Chris Loffredo wrote:
Thanks for the various comments. It is not a problem with the camera(s). Before I start using distilled water for everything (or risk more film experimenting), could it be the that I used the wetting agent in too high a concentration (didn't have any accurate measuring vessels on the order of 1cc)? Not very likely that tiny spots are from wetting agent -- I've seen that spot, but the spots are typically 2-3 mm across with more density at the edge than the center, like what you'd see if soapy water dries on a mirror (soapy water is exactly what the wetting agent treated wash is, of course). Tiny spots like you describe could come from dust that got on the film while drying (though that's more likely to come as tiny threads in most locations), dust in the enlarger or scanner, very localized increased development (can happen if you mix your developer and didn't get the alkali fully dissolved; remaining crystals of alkali will accelerate development locally whereever they come to rest by raising pH), or even a film defect (junk in the emulsion from the factory). If they print white, however, you can rule out pinholes, air bubbles in the developer causing local underdevelopment, and dust in the camera at exposure. -- I may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. |
#9
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Spots!
Donald Qualls wrote:
Jean-David Beyer wrote: Dale Strouse wrote: It could be that the distilled water you are using in your final rinse/wetting agent (distilled water) has minerals that upon drying are being left on the film surface. How much mineral content could _distilled water_ have? Depends how it was handled and stored after distillation. Water can pick up sodium from glass, I suppose so, but sodium ion is very soluble and unlikely to precipitate out onto the film. and ultrapure water will actually attack glass and etch it in much the same way strong hydroxide solutions can. Much slower, though. If stored or transported in metal, the water may dissolve metallic oxides or hydroxides. I have never seen distilled water transported in metal. If I buy super-market distilled water (being careful not to get simply ion-exchanged softened water), the stuff nowdays comes in plastic bottles. I have more confidence in the glass bottles. But I do not buy that stuff. I condense a lot of water out of the air here in New Jersey with my dehumidifier and then filter it and store it in glass bottles. Dehumidifier water certainly needs to be filtered as it can pick up a lot of dust -- though the dust mostly sticks onto the evaporator tubes. I would never drink the stuff. I probably get enough to wash films in it (though not with my normal washing methods), but I do not do that. I wash in tempreature-controlled filtered tap water. The final rinse in weak PhotoFlow is mixed from filtered dehumidifier water. This is good enough for 35mm negatives and, of course, larger sizes. If the distiller is overdriven (in an attempt to increase production rate) minerals may be carried over from the supply in droplets (as opposed to pure vapor transport from supply to collector). And, depending on the content of tap water used in earlier stages, a single rinse in distilled water may be insufficient to remove minerals deposited by the tap water. My water was so crappy that I got all kinds of crud on negatives. Installing 20 micron filter fixed this. When I got a better-designed mixer valve, I went to 5 micron filters on general principles. I recognize that these filters are useless against dissolved minerals, but they sure work on the lumps and chunks. [snip] Another advantage of distilled or filtered water -- stored with your chemicals, everything is at the same room temperature, and there's no concern about reticulation or fussing with the taps to adjust the water temperature -- just pour from the jug, and it's ready to go. I process film in my Jobo, and all water used goes through a Lawlor pressure balancing and thermostatically controlled valve, so everything is at the same temperature anyway. I have never seen reticulation, though I know it can be achieved, especially with older, less hardened, films. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 23:50:00 up 5 days, 8:49, 5 users, load average: 5.61, 8.69, 10.34 |
#10
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Spots!
Jean-David Beyer wrote:
But I do not buy that stuff. I condense a lot of water out of the air here in New Jersey with my dehumidifier and then filter it and store it in glass bottles. Dehumidifier water certainly needs to be filtered as it can pick up a lot of dust -- though the dust mostly sticks onto the evaporator tubes. I would never drink the stuff. I probably get enough to wash films in it (though not with my normal washing methods), but I do not do that. I wash in tempreature-controlled filtered tap water. The final rinse in weak PhotoFlow is mixed from filtered dehumidifier water. This is good enough for 35mm negatives and, of course, larger sizes. If you wouldn't drink the water, you certainly shouldn't use it for anything related to film. A dehumidifier lets the water contact all kinds of uncontrolled metal, as well as collected assorted minerals and potentially organic impurities from the dust you filter out. I wouldn't consider that water any better then filtered tap water. My water was so crappy that I got all kinds of crud on negatives. Installing 20 micron filter fixed this. When I got a better-designed mixer valve, I went to 5 micron filters on general principles. I recognize that these filters are useless against dissolved minerals, but they sure work on the lumps and chunks. That level of filtration should be adequate, but as you say, does nothing for dissolved minerals. [snip] Another advantage of distilled or filtered water -- stored with your chemicals, everything is at the same room temperature, and there's no concern about reticulation or fussing with the taps to adjust the water temperature -- just pour from the jug, and it's ready to go. I process film in my Jobo, and all water used goes through a Lawlor pressure balancing and thermostatically controlled valve, so everything is at the same temperature anyway. I have never seen reticulation, though I know it can be achieved, especially with older, less hardened, films. So you gain nothing by using distilled or stored, filtered water for temperature control -- but many others do, including myself. And you can have microreticulation that is almost invisible as such, that simply looks like exaggerated grain (and not terribly exaggerated, like classic reticulation, just "why does my TMX look more like Fomapan 100 today?" exaggeration). -- I may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. |
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