UNIFIED Enterprise Content Management

VINEGAR SYNDROME

Two opinions from a rec.arts.movies.tech thread:

OPINION 1

There are many “wive’stales” out there, but none of them has had any scientific backing as ofyet.What causes vinegar syndrome? Well, there are many. The most commoncause is improper storage in overly humid environments. Other causes arepoor processing and some types of scratch rejuvenation.So what are molecular sieves? They are small packets which are placed inthe cans of deteriorating film. They absorb most of the acetic acidvapors which are being released from the film base. These vapors (whichsmell like vinegar) are what attack the emulsion as well as the plasticacetate base support. If the sieves are used in tandem with proper coldstorage (below 50 degrees F and 40% relative humidity) then this will slowthe deterioration down to a crawl.[snip]Cleaning your film with commercial film cleaners should be limited tothose which do not have any oils in them, if you’re cleaning films withvinegar syndrome. Trichloroethane based cleaners, or just straighttrichloroethane, is very good. Ecco brand and J&R Film cleaner are good.Vitafilm and Surfaset have silicons &oils in them. Oils tend to trap in the acetic acid vapors, which willhasten the deterioration. Make sure you use a clean velvet or Webril Wipewhen doing a cleaning. Unless the print is dirty, however, it’s best toleave well enough alone. Passing a film through a cloth can potentiallycause scratches. Be very careful to stop periodically and shake out therag in case dirt builds up in it.[snip]

OPINION 2

I have heard conflicting advice on the best method for long term storage of>film negative. Room temperature, cool, or frozen?> What humidity is best?Jim,The National Film Board of Canada has begun tests on freezing monopackcolor negs, but beyond that I couldn’t tell you the long-term effectsof freezing your negative. Some members of the AMIA-L (Assoc. ofMoving Image Archivists) listserv expressed concern that if theproceedure was not carried-out with great control, then the base,emulsion or both could be fractured by the excessive moisture contentof the emulsion, due to expansion of the freezing water. There wereother issues as well, but I don’t remember them off-hand.At the present time, I believe the consensus is that the optimalstorage temperature is near, but not below, freezing with a relativehumidity of 30 – 40%.>Will dessicants in the film cans dry out the film too much?In a word, yes. Unless you are storing the film in a very humidplace, I would not put sillica gel in the cans. If you are storingthe film in a humid environment and cannot control the atmosphere inany other way than using sillica gel; store the film in an oversizedcan, on cores and laying flat (you should always store film on coresand laying on-edge – never store on reels and in the uprightposition). I would suggest you attach the gel canister to the can lidwith pop rivets (or other non-chemical based method to avoid harmfuladhesive fumes) over the center of the core. If you lay the packet inon top of the roll, you may cause the film to dry-out in the areadirecly beneath the gel and cause dimensional problems in the future.Check the canister and gel every two-weeks and turn the roll over toequalize the absorption across the web of the film. I really don’tknow how you would monitor the relative humidity of the can, but astable atmosphere is critical. Cycles of humidity and extreme drynesscan cause severe stress on the emulsion; causing fractures, acrossthe web shrinkage and maybe even vinegar syndrome. Who knows?Also, don’t store film in tight-fitting cans; let it breathe. Safetyhas a tendency to go vinegar if sealed-up in a can (not so much if thetemp is low), so keep the film in loose-fitting, oversized cans.If you can afford it, throw in a few molecular sieves per can; can’thurt (at least as far as we know!).> I definitely appreciate Jim Harwood’s helpful post. If the ideal>condition is below 50 degrees at 40% relative humididy, would it be a>good idea>to devote a refrigerator to storing my original negative for my films?I think so. The greater volume of air would be easier to stabilize andmaintain a good relative humidity level. A fairly inexpensive weatherstation (indoor/outdoor type) could be mounted on the door to keep acheck on the interior without opening the door. I would NOT suggestyou use a “frost-free” type of refrigerator, as they remove humidityto keep-out frost and could freeze-dry your film. If the fridge tendsto keep a dry atmosphere; put a few damp rags in a film can, punch afew holes in the top and place it in the bottom of the refrigerator.If too damp, use sillica gel cansiters to lower the RH. You will haveto experiment to find a method of regulation, but it should not be toohard. Freezing it worse than refrigerating it? Will the wrong temperature or humidity wreak havoc on glue splices?At the present time, I would say cold storage, but don’t freeze just yet. Until more testing is conducted, try a method that has had somesuccess in the past.As for the splices; they would be my least worry. A cement splicecan be remade without too much fuss; and without loosing a frame. Iwould worry about fungus, mold, air pollution, solvents and othernasties attacking the emulsion; along with the natural tendency ofdyes to fade over time.The biggest problems in preservation of color negative are:1. Dye fading – solution: copy when dyes start to fade. That’sabout all you can do. Forget digitizing; the storage medium won’tlast as long as the original negative and “Who the heck can afford itanyway ?”.2. Shrinkage of base – solution: maintiain proper humidity and temp.Make new dupe preservation neg when approaching 0.5% linear shrinkageof the film. Shrinkage should be measured over the length of one-footof film and expressed as a percentage of the total original distanceon a fresh piece of properly-pitched stock (get the right pitch, itmatters!). We use shrinkage-gauges built by Mauer in the 50’s; Idon’t know what to suggest for a homebrew measuring device. You starthaving printing problems (movement and breathing in the printer gate)at about 0.6 % on “standard” printers. When you exceede that amount,you have to have it printed on a modified printer; one with thesprocket teeth cut-down and movement is almost assured when you printthat way.3. Emulsion damage – don’t handle the film excessively, but doexercise the roll at least once a year by rewinding. Some claim youshould store the film emulsion-in (contrary to lab practice!), but weat the LOC store all our originals emulsion-out. Why? I guess it’sjust easier to handle when printing when would emulsion-out.4. Environmental damage – Solvents, ozone, gases, etc. attack thebase, emulsion or both. Keep storage areas clean and free fromvolatile chemicals and or liquids.Whew! Hope that helps somewhat.  Frank Wylie  fwylie@infinet.com