are plastic film holders more subject to static electrictygreenspun.com : LUSENET : Large format photography : One Thread
I am working on a series of large format aerial photographs. I am using Lisco plastic film holder because they wiegh less than my wooden ones, however I am concerned that the plastic ones will be more apt to be charged with static electricity which might effect the negatives. So far, no problems but since this is a rather costly project I want to stack the cards in my favor. I thoughtI'd better ask for input from the Experts. Are plastic film holder more prone to static electricity than wood in aerial photography? Thank you for yopur opinions and Happy New Year!
-- John Kasaian (firstname.lastname@example.org), January 02, 2002
John, if you move the darkslide slowly, static should not be a problem with your Lisco holders. Does wood even generate static electricity ??
-- Michael Mahoney (email@example.com), January 02, 2002.
I have never had a problem with the plastic ones and do alot of shooting both aerials and studio. If in doubt, you can always wipe them down with a good anti static cloth.
-- Scott Walton (firstname.lastname@example.org), January 02, 2002.
Thank you for your advise! I'll stick with my Liscos for aerial work and take your recommendations regarding removing the darkslides slowly and using an antistatic cloth. Thanks!
-- John Kasaian (email@example.com), January 02, 2002.
Don't know if wood generates static but from all the lightening struck trees I have seen it must attract it.
-- Dan Smith (firstname.lastname@example.org), January 02, 2002.
John: The answer is definitely yes. You can check this with a static meter. Most plastics can generate large amounts of static when rubbed. Some can generate several hundred volts. Wood does not generate static becuse wood has a moisture content in most environments that are fit for humans. Moisture dissipates static electricity. Metals conduct static and do not store it. One way, the best way of dealing with static is controlling the relative humidity in the environment. Your basement is probably the best place to load film holders because basements are generally more humid. In winter it is important to maintain a relative humidity of at least 50% at least while you load holders. Watch out for carpets and rubber soled shoes. Those can help store static in your body which can be discharged when loading holders damaging yout film. Do not wear ties, these are specially bad for static, or synthetic fiber garments on top or under. Cotton and leather soled shoes are best.
-- Julio Fernandez (email@example.com), January 04, 2002.
Dan: trees attract lighting for a totally different reason. They provide electrical contact with the ground which is what lighting really seeks. Trees work in similar fashion as lighting arresters, which also provide an electrical link to the ground. That is also why golfers, -with their metal spiked shoes are also favoured by lighting. Come to think of it, wearing golf shoes while you load film may not be a bad way of draining static from your body. Before trying it, though, get permission from your wife!
-- Julio Fernandez (firstname.lastname@example.org), January 05, 2002.
Thank you for all your replies. My concern about static electricity come in part because the aircraft(all aircraft actually) need to be grounded before refeuling, and static charges have "cooked" ungrounded aircraft during refeuling in the past. Perhaps I'm being overly cautious, but if an airplane could accumulate enough static electricity from flight to cause a discharge, then would my plastic film holders be subject to the same sort of thing? I haven't had trouble with them when I use them on the ground. After a flight I can't go around shocking unsuspecting people like I did the last time we got a new carpet, so I'm not storing static electricity. Perhaps I should load up all my holders, wood and plastic, and rent a bigger plane then see what I pull out of the soup? Do people get Grants for this kind of stuff? Julio's comment were especially interesting. I think I read something somewhere about static charges possibly being a problem(Ansel Adams?) but I don't think it differentiated between plastic holders or wood. Thank you once again for your interest & advice!
-- John Kasaian (email@example.com), January 05, 2002.
Most film holders today are made of conductive plastic. This helps reduce static change, but does not completely eliminate it. Because I too have lots to risk, I have replaced my plastic slides with aluminum slides. I never store my loaded films holders in Ziploc bags because they build static charge quickly. Instead I use plastic bags that are intended for holding electronic boards which are designed to completely eliminate any charge build up.
-- Stephen Willard (firstname.lastname@example.org), January 06, 2002.
Re. To Stephen's point, yes, the materials used for film holders contain carbon, and carbon helps dissipate static charges. The discharge however can come about when objects of different electric potential come into contact, thus it is most important not to have charges anywhere around your film. For the discharge to come about the potential difference has to be great enough, and one of the items must have sufficient voltage for the discharge to take place. As I cautioned before, beware of synthetic fiber garments, they are probably the greatest source of static, aided by rubber shoes. At one time in a research project in a plant where static was a special concern and dangerous, I scanned a person, -a lady, with static meter. Just looking at the meter, thanks to the synthetic garments, you could tell in what part of this lady's geography your static meter probe was next to. She was indeed high voltage! Black-soled rubber shoes my be OK, -because of the carbon in them, but only if there is enough of it. Also, peeling adhesive tape can cause static discharges which may be quite visible in the dark. For all practical purposes however the greatest concern has to be very low relative humidity, lower than 40%, synthetic garments and some syntethic carpets and plastic flooring. Men's ties are by far the worst offenders and should be banned from the darkroom. What's best? ceramic tile or wood floors, cotton garments, leather shoes and summer weather. When there is little concern? in basements where the humidity stays no lower than about 50% and in regions where high humidity prevails. Air conditioners lower humidity but in summer, but heat would have to be added to control humidity to 50% so that even with air conditioning, the humidity is likely to be higher than 50% in most locations in summer, at least near or south of the 49th parallel. If you have never had a problem I would not worry about it but if the consequences of a such a problem could be costly as in John's case, prevention is easy and may be best.
-- Julio Fernandez (email@example.com), January 07, 2002.