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Help!!
I have very many diptera specimens kept in plastic store boxes. Recently, the specimens in the boxes have been subject to attacks of mould/fungi. I also have many specimens in wooden store boxes and these are not attacked, so I guess that the sealed atmosphere of the plastic boxes is conducive to mould. Thankfully, I have been able to rescue the vast majority of specimens by cleaning them with alcohol, using a fine brush. I would appreciate some advice from Museum professionals and amatuer dipterists on preventing mould.

An additional note. My collection is housed in a dry-lined cellar, in which I run a de-humidifier. However I am now suspecting that the atmosphere in this room is still too humid and theerfore not suitable, so I am going to move the boxes into a room in another part of the house, where the atmosphere should be less humid. My guess is that this is the root of the problem, as my collection has never experienced mould attacks as frequently as in the last year (I moved the collection into the newly dry lined cellar about 18 months ago).

Can anyone advise:
1. Will moving the collection to a better aired room help to prevent attacks?
2. To 'sterilise' the boxes against any unoticed mould, I am leaving them open in a warm dry room for a few days - will this help to kill any spores off ? I am assuming that spores need a humid atmosphere to thrive.
3. Would anyone recommend NOT using plastic store boxes, or is it safe to do so, as long as they are kept in very dry conditions?

All advice appreciated!
:(

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Hi Nigel,

If your specimens are in air-tight boxes and still going mouldy then I think perhaps they haven't been allowed to dry completely after pinning. Either that or the air really is overly damp.

I have never had mould problems when storing my specimens in wooden boxes in a normal, centrally-heated house. Fungal spores exist all around us, and most will survive happily even when it is dry. However, they won't grow until there is enough humidity for them.

I'd suggest putting the open boxes close to (but not on a radiator) in a warm, dry room and allow the flies and boxes to dry completely. Then store them in a warm, dry place. If you are worried about humidity perhaps try pinning small packets of silica-gel inside each box to absorb any humidity. These packets can be taken out regularly and re-dried on a radiator.

It might be that the atmosphere inside you cellar isn't particularly humid, but the cool temperatures caused whatever humidity there was to condense out on the specimens.

Cheers, Chris R.

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Thanks Chris that's reassuring. You'll be pleased to note that none of my Tachinids were affected! :D

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Nigel

As ever, Chris's advice is spot on. I used to work for a large heritage and nature conservation charity, and some of my colleagues did some very interesting research into collections care issues such as relative humidity and fungal growths.

If you continue to have trouble after following Chris's advice, get in touch and I will give you contact details for a couple of conservators with expertise in this area.

The only thing I can add to what Chris has said is that cellars are tricky in terms of controlling their RH, and dehumidifiers are often just not up to the job - it depends on the construction of the cellar and whether it is also heated as well as the power of the dehumidifier. Also, if you are planning to clean the boxes, don't use any sort of regular household detergent - an amazing number of fungi will happily feed off detergent residue. Wooden boxes have the advantage that they give off gases, to varying degrees depending on the type of wood, which discourage things like fungal growth.

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Susan,
Many thanks for the very useful advice. I was not intending to clean the boxes out, but just give them a thorough drying out in a warm dry room/space (I am thinking of the airing cupboard). Do you think it might be necessary to clean the boxes? I should note that the boxes were not badly contaminated - just two to five specimens in each box were in need of a clean up.

Following your advice, I think I will try and get as many specimens as I can into wooden store boxes and I will definitely be relocating all boxes to a ground floor/first floor, well ventilated room.

Chris and Susan - Thanks again for the very helpful advice.:)

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Take great care with plastic boxes. Many plastics slowly release chemicals which discolour specimens.Agree with all of the excellent advice given but even so check all boxes regularly. Say every three months in a cycle.Label the boxes with a calendar to keep track. This is especially important if you are not using insecticides.
Robert

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Robert is right about plastic boxes, and about regular checking. Theoretically, any plastic intended for food use should be inert for practical purposes. In reality, we found that this was not totally reliable, but Tupperware proved suitable and also Lakeland Plastics, who I expect you have heard of, based in Kemble, are very obliging if you ask them what their products are made of - go for polyethelene. Lakeland quite like being able to advertise that their products are "museum standard" or "as used by the National Trust" and are always interested issues of collections care (although may be a bit more atuned to the needs of 18th century furniture and antique textiles than natural history collections). Remember that lids and bases are usually of a different chemical makeup with plastic boxes, because of the practicalities of rigid bases and flexible lids. We were concerned with the storage of all sorts of objects, not just natural history collections, and I dont recall ever looking at the composition of specialist entomology boxes - I guess you just need to ask the suppliers or manufacturers.

I think you do need to clean the boxes if controlling the RH is not effective, as they very likely have spores that may cause trouble. You probably need to clean the pins as well if problems continue. Use alcohol, acetone (test first in case you melt the plastic) or a non-ionic detergent like one of the Synperonic products (originally developed to clean out the insides of oil tankers and such like).

The big advantage of plastic boxes over wooden is cost. Wooden collections boxes are significantly more expensive. Also, my line about wood off-gassing was a bit throw away - its true up to a point, but wood may also give off gases that could be just as problematic as plastics and it is an incredibly complicated subject - each wood is different. If the boxes are lined with a textile, the dye in the textile may off-gas, as might the glue joining it all together. You also need to know if the wood is treated with anything. Untreated wood can be an advantage because it is porous, so you can control relative humidity externally ie the RH of the room, not the box, and this is most practically achieved by controlling the heating. Controlling RH is one of the black arts of heritage conservation, and if you want to know more about the technicalities, I can give you some references that go into eye-crossing detail.

I have just been given some lightweight aluminium boxes, complete with little aluminium specimen pots with glass lids, and will be putting my rather haphazard personal collection in these - if anything hideous happens to them, I will let you know, but it strikes me that aluminium boxes might be a very reasonable solution, so long as RH is controlled.

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Thanks everyone, This is tremendously useful advice. I have stored some of my reference insects in plastic boxes for twenty years with, until now, no real problems. However, on the balance of the discussion here I think I will move everything into wooden store boxes. I will continue to use plastic only for short term storage of specimens awaiting ID and labelling. All will be kept in a well ventilated, warm room.

Now the issue is one of cost. As Susan says, plastic is way cheaper. A wooden storebox from Watkins & Doncaster is around ?30 - ?40! I was fortunate in getting four used boxes from W&D last time I bought some and these were only ?15 each. These are not available now, so I am posting a separate thread asking about suppliers of wooden store boxes. ;)

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Ventilated is good, but not too warm Nigel. The issue is relative humidity and the rule of thumb for controlling it to a suitable level for collections is to keep the temperature of the room at about 5 degrees C higher than the outside temperature, but no higher than 18 degrees in winter and 22 degrees in summer, and no lower than 5 degrees at any time. This can be fairly simply achieved these days with a thermostat which switches an oil or convection heater on and off automatically, and by making sure curtains are closed during hot spells. Because your boxes will to a large extent have a microclimate of their own, Chris's suggestion of a little packet of silica gel in each box will ensure there are no damaging fluctuations of RH. The best silica gel is Artsorb, which can be obtained from http://www.conser...ign.co.uk/. Silica gel lasts pretty much indefinitely, but does need to be conditioned ie before you put it in the boxes, leave it somewhere with a suitable RH for a few weeks so that it equalises, and re-condition it every so often - perhaps in conjunction with your checking for insect damage cycle that Robert suggested.

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Thanks for the excellent advice Susan. I have now put my boxes in a room that has no window and has a room on either side of it. It stays a fairly constant temperature - about 20 degrees (so a little more than recommended for winter). It has a chimney providing good ventilation. The boxes are inside a large wooden cupboard, which provides some insulation against fluctuating temperatures in the room. The cupboard is NOT shut tight, so there is a good flow of air through it. I think this will be the best I can manage at home. As far as longer term storage is concerned, I am intending to pass a load of my stuff on to Liverpool Museum, and I will just retain critical stuff that I need for comparative purposes, when determining species IDs.

I will be keeping up regular inspections of boxes, and in fact have been doing this - that's how I discovered the outbreak of mould in the plastic boxes. However I was only doing them on a six monthly basis. This will now be increased to 3 monthly.

Thanks for the silica gel link. I will be making immediate use of it! :D

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Sorted:D