Thread subject: :: Pinning flies and wasps and some curious questions.

Posted by Susan R Walter on 08-09-2007 17:14


Paper: The paper normally used for photocopying or office printing is usually 70 or 80 gsm (grams per square metre). Some places use a heavier grade of 120 gsm photocopying or printing paper, especially if they use a paper with a letterhead preprinted on it. The paper I use for botanical specimens is a heavy weight cartridge paper of the sort that artists use for sketching. This is 220gsm (100lbs), so quite similar in weight to what Tony is using for his boxes. I suggest talking to your nearest artists supply store - many of them also supply museums and have a good understanding of natural history collections requirements.

The term Acid Free is used to indicate that the paper is stable and will not become brittle and yellow over time. The terms Museum Grade/Quality, Conservation Grade or Lignin Free also indicate suitable paper - they all mean more or less the same thing. The reason rag based paper is better is because it is more stable because it is hand made in small batches, with few additives and the principle fibre is a plant fibre other than wood. The lignin (a type of cellulose) from wood pulp in modern industrially produced paper breaks down quite quickly, through exposure to visible and invisible (UV) light, producing an acid and causing the paper to go yellowy brown and brittle. Leave a newspaper half in the sun and half covered for just an hour and you will see what I mean.

Printers: Laser printers are better than dot matrix because the ink is waterproof. Neither is considered to be truly museum standard because neither is adequately light fast though.

Foam Bases: Polystyrene aka styrofoam aka expanded polystyrene foam is completely inert, so will not produce nasty gases or acids that will destroy your specimens. It is also cheap and readily available eg in your local hardware store as ceiling tiles. Environmentally it is a problem if used as a packing material because it does not break down (ie it is inert). It can be safely burnt, which produces something perfectly inocuous (hydrogen and something I think from memory, but can't be bothered looking it up to check). The disadvantage for display boxes is that it does not cut neatly - crumbles all over the place and just doesn't look professional, and over time, it will develop bigger and bigger holes from pins being stuck in it over and over.

Plastazote is a brand name for high density polyethelene foam. It is also inert and comes in a range of densities from flexible to rigid. It is slightly more trouble to obtain, but the specialist entomological suppliers will all have it. It is also more expensive, but cuts to size and shape easily and neatly, and the surface is 'self healing' ie it does not deteriorate over time with being stuck with pins.

Dessicants: I recommend ArtSorb, available from Conservation by Design, but you must use it in the way described by Tony and periodically 'refresh' it in the oven or it is a waste of time.

Storage Boxes: Your storage box should obviously protect the collection from physical damage - being knocked etc. You need to be aware that the box itself may cause problems for the collection. It needs to be well sealed to exclude pests coming in, but that means that internally it will create its own microclimate, which can lead to conditions suitable for fungal infestation. To control this, and keep conditions as generally stable as possible, make sure the boxes are kept somewhere that the temperature does not fluctuate (and ideally is probably about 16C - not too hot, not too cold. If in doubt, colder is better than hotter.) The dessicant gels/crystals will also help with this problem, keeping the relative humidity (RH) stable. Almost all boxes will produce gases which can harm the collection long term, especially if the RH is too high. As well as the cellulose in paper, coatings such as paints and varnishes, the solvents in glues, certain types of plastics, certain types of wood and dyes or rubber backings in textile linings are the worst offenders.