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> Mould growth on films and prints: |
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Mould growth on films and prints.
Ian, I think you are being very brave to state that 60% is the RH that these spores germinate, unless you have something in print from an acreditable source. The consensus here in Cambridge is that it is much lower, possibly 45 to 50%, but again nothing in print. (Film conservators in Cambridge University Museums, informal chat.) But, I want to get to the bare bones of this one and I see RH as the key issue. I have a hygrometer and in the spell of warmer weather we had in May it was showing 19%, yesterday 28.06.12 when it was thundery here is was 29%, today, less humid it is slipping back down again to 26%. It has never been higher than 32% ever. For me, I assume modern living has designed out the need for me to worry too much about mould issues unless I move home to somewhere it is damp, like an old property.
Regarding drying time, my own films were hung up next to our coal fired room heater/central heating boiler for at least a day before mounting. In my student days, I worked for Gevaert as a lab technician attached the reversal and cine film processing lab. Here the slide films were blasted with hot air at about 110 deg F for about 20 mins before going upstairs for mounting. No drying problems in either case. Last edited by AlanJones; 29th June 2012 at 12:26 PM. Reason: spelling: Can something be done about our spelcheck? |
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Here are a couple of links regarding RH and mould growth
http://cool.conservation-us.org/byto...r/npsmold.html http://epi.publichealth.nc.gov/oii/mold/conditions.html I have aways believed that safe storage for most organic things is a temp of 20º c and RH 50-55% It is important to understand that RH will fluctuate with temperature as warm air holds more moisture. If for instance the amount of water in the air (the absolute humidity) Stays the same As the temperature falls the RH will rise. as it rises there are two ways to reduce it either by heating the air or my removing water from it. But as we are aware science is constantly reviewing things and I may be wrong, but having been involved on the edge of conservation these have been the guide lines that have been generally accepted
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Ian |
#14
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Mould growth on films.
Dave and Ian, thanks for your replies. Really interesting links, thanks Ian.
Home for me is a top floor flat just out central Cambridge and I am de-humidifying. A couple of years back I managed to get £110 off a Honeywell de-humidifier in an Argos post Christmas sale. Without it, heat would be unbearable here especially when humid in Summer. It is sufficient to treat 12,000 cubic feet and is close on the volume of the flat and takes 2kWh to run. Expensive, so I use it intermittently, when I am in, usually about 8 hours a day. If water has anything to do with humidity in my local area I have The Vicar's Brook and Hobson's Conduit feet from my flat and River Cam less than a quarter mile away. As a second line of defence, I have indicator silica gel in the cupboard where I keep my developed films and camera gear. The orange coloured silica gel turns dark green when it has absorbed all the moisture it will. Then it is a case of undoing the bags and emptying out the contents into a saucepan and drying it out with minimal heat on the cooker hob and re-bagging when it has turned back to orange. Anyone wanting this product it is available on ebay, (Supplier: cazboot-001 in Llanelli, Sth Wales. 7 x 100g bags for £8.99 post free.) I won't say anything more to other readers than I usually look at the silica gel weekly until it shows signs of changing colour, then perhaps every two days after. Conditions will vary. The humidifier is best looked at daily, if missed it could overflow. . . . a mistake I made just the once, resulting in a wet carpet. |
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Alan
You are doing everything right and more so than most of us. If you wanted to take things further you could look at data loggers to see what is happening over a period of time, you will probably be amazed at the fluctuations that occur we use these. Well an earlier version. http://www.preservationequipment.com/Store/Products/Equipment-$4-Tools/Instruments-$4-Meters/Tinytag$9Temperature-and-Humidity (Sorry this does not seem to work as a link, you may need to copy and paste it to your browser) Silica gel is a great idea, but even that has moved on, see here. http://www.preservationequipment.com...erials/Pelsorb
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Ian |
#16
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Mould growth on films and prints:
I think it now safe to say that we have covered this subject as far as we need to, despite further reading and asking questions on my part.
We have to accept we can't stop the spores from getting on the film, but we can stop them from germinating and causing a problem by keeping them in a dry environment. For those looking to monitor their situation and buy a hygrometer to indicate 'relative humidity', they cost from £10.00 and ebay is a good place to start to look. For those with ruined slides or negatives, it is a case of if all else fails, I would think improvement can be obtained to get a good result by digital means. A good place to start looking is Wikipedia|Digital Scanning for film. As I have said, 'If all else fails'. |
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