what is the best way to protect film from airport x rays

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I could use some advise as I am very worried about over 700 rolls of film I shot here in Turkey the past six months for my web site project on www.losttrails.com Many of the rolls are shot at 3200 asa! but most are black and white 400 asa. I have some x ray bags but I have heard different reports about the overall protection they can give. I heard some of the newer x ray machines will scan right through the bag! I spoke with federal express about the possibility of shipping them back but they tell me they can not guarantee the film will not get x rayed. airport and airline employees have been similarly unhelpfull. It is amazing to me that after such a huge investment of time and money I must put all this at risk now. Can anyone advise me what else I can try and do.

-- shane solow (ssolow@mindspring.com), July 03, 2001


You're right about the new X-ray machines, but they're used for checked baggage. Supposedly, film under 1000 ASA can safely go through the X-rays with your carry- on baggage, but I always ask for a hand check. Unfortuneately, not all airports will do hand checks. I suggest that you ask VERY nicely for a hand check, and put the TMZ in lead bags in case they make you put the film through the X-ray. Chances are the Tri-X will be OK.

-- Steve Wiley (wiley@accesshub.net), July 03, 2001.

Even if you gain a hand-check at the airport, you will usually need to open every can to demonstrate there's a film cannister inside. Security agents tend to drop a few films on the floor in the process. That can take forever if you have lots of film. I've had luck at security checks in US, Asia, and Europe by putting my films in clear ziplock bags, no cans. I almost always get a quick hand check of the entire bag of films without opening it. Put maybe 40-50 rolls per large bag, so they can see every roll without dumping them out. Only problem in recent years has been at UK airports where they simply insist on putting films through the machine, no exceptions (and of course treat you like an idiot for even questioning whether their machine is safe). Whatever happens, don't throw a fit, because you're sure to make your security check more prolonged and possibly more damaging that way. Good luck!

-- Tim Nelson (timothy.nelson@yale.edu), July 03, 2001.

I have very similar experience with an UK airport. I was wondering why Ilford Delta 3200 fact sheet bothers to put "At airports, request visual inspection of this film, and carry the film in hand luggage." Do they make UK version of the fact sheet without this statement??

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), July 04, 2001.

I can't give an answer but in case this point hasn't been thought of I'll add an extra piece of caution.

Xray dosage as with any exposure is cumulative. That means that if you fly out and have your films Xrayed and fly back with the same film (whether exposed or not), and so have it Xrayed again' it gets a second dose. So, if as we're told films to 1000 ISO are safe, for a double passage only a film to 500 ISO would be safe.

If you go on a multi-stage trip with a number of flights you can easily build up a significant cumulative dose which could bring even modestly rated emulsions into the danger zone.

The same build up of possible fog applys of course if you take film out and bring it back un-used (2 Xray passages), then take it out through an airport again on a second or even further trips! I mark film boxes/tubs to show which have been through airports and would make sure that they were used at home rather than taking then on further flights.

One further point, never pack films to go in the aircraft's luggage hold, Xray dosages of such luggage can I understand be much higher than for hand luggage.


-- Trevor Littlewood (trevorlittlewood@aol.com), July 04, 2001.

The lead bags might offer insufficient protection. I read somewhere that the operator of the xray machine can increase the level of the xray to the point where it sees through the lead bag, and consequently the film gets even more exposure. (otherwise the terrorists would put their weapons in lead bags, right?) I've had success with the transparent ziplock bags, as suggested above, with a couple of rolls of TMax3200 thrown in as an excuse to not have the whole lot xrayed, but there has definitely been a change in the attitude of inspectors.

I've never developed film in a hotel room, but I'm considering it in the future. But 700 rolls? Maybe developing there could be arranged somehow.

-- john stockdale (jjss@bigpond.net.au), July 04, 2001.

I have traveled a lot, world wide, and never had a problem w/ my film going through the baggage scanners, even in third-world countries. I have, however, had issues w/ hand checks and losing cannisters of film "mysteriously".

-- Sassy (sassafrassy@geocities.com), July 04, 2001.

I was just travelling for two months and decided to develop my TMY and TMZ in the hotel room. After practicing the techinque before I left felt comfotable the only thing I couldnt control would be the water quality. But some tips would be to get your development time for 75 degrees instead of 68 as not all hotels' water goes that cold. Also that you might want to develop 4 rolls at once instead of 2 since you shoot more volume on location. The main reason I did this was to get some feedback to see if I needed to go back and reshoot anything. In the future I still may develop in the hotel room but it was a bit of a pain.

-- Russell Brooks (russell@ebrooks.org), July 05, 2001.

The best way to shield film form X ray is put them in a sterling silver container. Silver is the provide the best protection against x ray, much better than lead; a silver box of 1 mm thickness can stop 99.5% if xray. (Not silver plated )

-- martin tai (martin.tai@capcanada.com), July 27, 2001.


Are you saying that for the same thickness of metal, silver is better than lead at protecting from x-rays? If that is what you are saying, some supporting reference would be appreciated.

-- Michael Feldman (mfeldman@qwest.net), July 27, 2001.

Michael When I investigate the protection from Xray of various Minox spy cameras, I was surprized to find out that silver is better than lead in absorbing Xray. There are different Minox camera models made from steel, brass aluminium, and pure silver ingot. The aluminium body Minox provides almost no protection, while the silver Minox absorbs 99.8 % of Xray

X ray protection of Brass, Alumninium and Silver camera

Lead's Xray absorption index Mu is 52.2, for silver, Mu=60.4 Residue Xray = Iniitial Xray * exp (-Mu * d) Substitude d= 0.1 cm

We have Residue Xray of 1 mm of lead = 0.0054 Residue Xray of 1 mm of silver = 0.0024

There is only one camera in the world made of silver ingot, ---- Sterling Minox LX --- it is a collector item, very expensive, the better choice is to find a sterling silver box.

-- martin tai (martin.tai@capcanada.com), July 27, 2001.

Martin, The reference you provided was written by you on another forum. I don't consider this to be a "reference". Can you provide a scientific source to back up your claim (that the same thickness of silver is a better than lead in protecting film from of x-rays)?

I don't think that the primary concern is about a single roll of film left in a camera, rather it is to protect MULTIPLE rolls of unexposed and exposed film passing through airport x-ray machines. Therefore the composition of the camera is probably not relevant.

Lead has a density of 11.35 g/cm3, and silver has a density of 10.5 g/cm3. I would assume that this has something to do with the ability to shield from x-rays (although since I am not a scientist, I certainly could be mistaken). The medical and dental communities seem to use lead shields to protect patients and medical personnel from unwanted x-ray exposure. Here is a description of lead (Pb) that I found at the Los Alamos National Laboratory periodic table web site: "The metal is very effective as a sound absorber, is used as a radiation shield around X-ray equipment and nuclear reactors..." The description of silver (Ag) does not mention x-ray shielding. http://pearl1.lanl.gov/periodic/

-- Michael Feldman (mfeldman@qwest.net), July 28, 2001.

Michael I stated clearly in my first post about using SILVER BOX to shield MULTIPLE ROLLS OF film: "The best way to shield film form X ray is put them in a sterling silver container. Silver is the provide the best protection against x ray, much better than lead; a silver box of 1 mm thickness can stop 99.5% if xray. (Not silver plated ) "

The aborption factor Mu of silver =60.4 and Mu(lead)-52.2 is scientific facts, just like specific weights etc.

-- martin tai (martin.tai@capcanada.com), July 28, 2001.

As why dentists use lead apron to shield Xray and not silver lined apron clearly due to cost.

The key facts I provided in my article are the Xray aborption coeficients of aluminium, silver, steel and brass. I got in from a reference book in a big library, I forgot the name of the reference it is a three inches thick book.

I think these xray absorption factors must be listed in many other references.

-- martin tai (martin.tai@capcanada.com), July 28, 2001.

Martin, You have not provided an independent source that says silver is a better protector than lead from x-rays. Although I am not a scientist and do not know whether you are correct, you are simply quoting yourself, or your own interpretation of certain facts (absorption rate), when you mention references. I would like to see some other conclusive reference that says (for a given thickness of metal) that silver protects better than lead from x-rays.. A 20 lb. silver protector used by a doctor or dental office would cost about $1350. That is not an exorbitant cost if it did indeed provide better protection than lead.

-- Michael Feldman (mfeldman@qwest.net), July 28, 2001.

Michael, I am counting on you to spend some time in the library, and dig out the Xray absorption coeffiencts--- that will be the best way to provide independent source. I did photo copied that page, however, there is no book name on it the page heading is ELECTROPHYSICS and the title of the article is "X-Rays" written by Herman E. Seemann. He tabulated the xray absorption data, and also provided half absorption thickness data, ie, the thickness of the material required such that the X ray is absorped 50%. Again, the half absorption data for silver is thinner than that of lead-- clearly indicated that silver is a better Xray absorption material than lead.

The absorption formula I posted was from section 63 of that article "X ray Absorption, Opacity of Materials."

-- martin tai (martin.tai@capcanada.com), July 28, 2001.

Martin, I don’t believe that either of us is knowledgeable enough about the physics of x-rays to understand the context and meaning of individual statistics. Being able to do math is one thing, understanding the context of the data is another. However, I have done some research on the web and have contacted a person who is qualified in these matters.

I sent the following e-mail to Joe V. Pace III of the Oakridge National Laboratory, Nuclear Analysis and Shielding Section, Leader of the Shielding and Dosimetry Group. The Bio and Vita for Mr. Pace can be accessed at: http://nas.cped.ornl.gov/nas-staf.html

“Mr. Pace, There is a discussion going on at an internet chat site dealing with photography. One of the issues that has come up is shielding of conventional photographic film from x-rays (primarily at airport security). One person says that silver is better than lead (for a given thickness of the metal) in protecting film from x-rays. He claims that it is because silver has a higher x-ray absorption factor than lead. Are these statements accurate? Thank you for your time.”

Here is the response from Mr. Pace:

“Mike: I'm not aware of the mass absorption coefficient (MAC) for Ag [Silver] being higher than Pb [Lead], unless it's become part of the Darwin Evolutionary Theory syndrome, which so many believe in these days. If u have access to Rockwell's Reactor Shielding Design Manual, or another reference which shows MACs, u'll see that the MAC for Pb & Ag approach each other in the 1-3 MeV region, but never cross. Additionally, the mass density of Pb is greater than Ag. The absorption is proportional to the Z number, which is higher for Pb than it is for Ag. Sincerely. JOE”

In addition I have found the following information at http://www.nucleonics-online.com/622.html entitled “Calculation of Transmission and Shielding”

“For practical applications, two Total Interaction Coefficients were defined as combinations of Partial Coefficients: The Attenuation Coefficient and the Energy Absorption Coefficient. It is these two coefficients that are being used for the calculation of Transmission and Shielding of photons [x-rays].”

This means that both absorption and attenuation [reduction] coefficients need to be considered. The following charts show that with respect to the Total Interaction Coefficients (absorption and attenuation), Lead (Pb) outperforms Silver (Ag). http://www.photcoef.com/212182.html http://www.photcoef.com/212147.html Note that Pb outperforms Ag even when considering the individual factors (attenuation and absorption).

-- Michael Feldman (mfeldman@qwest.net), August 01, 2001.

Take a bus.

-- Mark (marktt@nac.net), October 25, 2001.

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