Dust to dust................

[(John Cooper) <jco@xxxxxxxxx>]

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From: John Cooper  <jco@nhm.ac.uk>
Fri, 2 Dec 94 10:25:05 GMT
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From: Paul Jeffery  <paj@nhm.ac.uk>
Thu, 1 Dec 94 13:33:25 GMT
Paul Jeffery writes: 
>>>> I am interested in the perennial problem of dust in collections.  A 
brief scan of works dealing with the curation of geological materials shows 
that the implications of this problem have been largely ignored.  It is of 
course universally true that dust is a health hazard and also a fire 
hazard - dust explosions in particular can be very easily ignited and every 
bit as devastating as gas explosions.

It may, however, not be widely appreciated that all dusts are not alike.  
The damage caused by dust in collections is going to depend on the nature 
of the dust itself, this in turn will depend on what the sources of the 
dust are, which again will depend on factors such as geography, climate, 
housing and storage media.  Sources of dust may be external (traffic, 
pollen & spores, factories, climate/terrain etc.) or internal (fabric 
fibres and skin flakes from staff; adjoining collections ((eg. skins & 
stuffies)); building material such as old plasters, asbestos fibres, etc.)
Many of these sources of dust supply will be steady and prolonged, 
while others (building refurbishment, drilling and preparation of 
specimens, emergency generators, fires etc.) will be transient but 
localised and intense.   

Climate control can be both a blessing and a curse - in a dry atmosphere 
(low relative humidity) dust (depending on its nature) will stay suspended 
longer and its distribution and redistribution will be greatly affected by 
movement of staff and static electricity.  In a high rh atmosphere this is 
less of a problem as dust settles more rapidly, but this is often in 
conflict with what is best for the collections.  Air conditioning systems 
used to maintain a steady rh can again be both help and hindrance because 
although the air supply is filtered, this filtering is often not complete. 
Here at The NHM, in the middle of a traffic-bound city, particulate matter 
from diesel-engined vehicles ("soot") appears to be small enough to bypass 
these filters and builds up constantly.

Whatever their origin, most dusts are composed of fairly stable organic and 
inorganic substances, which, while spoiling the appearance of specimens do 
not actually seem to physically degrade them.  Organic dusts may decay 
and encourage insect pests, and in the process of decay may yield small 
quantities of organic acids, but I've no knowledge of whether this 
actually takes place.  Inorganic dusts, such as silica are clearly abrasive 
and so pose an obvious threat to specimens when they are moved, handled, 
etc.  A more serious threat might be if a museum site was near a chemical 
plant where emissions included chemically-active dusts which might react 
with the surface of specimens; but I am speculating and know of no examples 
of this.  

The problem of removing dust is where potential for harming specimens 
exists.  Where a specimen is robust and inert then simple washing in water 
seems to be entirely satisfactory.  I have cleaned micro-molluscs this way, 
from collections made more than 150 years ago, which have become grimed by 
dirt and dust from London's varying pollution sources during these years, 
in order to take SEM photomicrographs.  These showed no evidence of damage 
due to the dust and came up pristine with no surface pitting (other than 
what was already there due to preservation) visible under the SEM.  However 
fragile, friable and pyritic specimens cannot be treated this way and 
require the attentions of specialist conservators.  Robust pyritic 
specimens could presumably be cleaned in organic solvents quite 
satisfactorily.

Well these are some thoughts on the subject of dust, some of it rather 
conjectural.  Is there anybody out there who has looked at this in more 
depth.  I suspect specialist conservators who deal with man-made materials 
like textiles, paper and art material may well be very-much better informed 
on this; and there is probably a specialist literature on this subject if 
one just knows where to look.  What thinkest Ye? <<<<
>
>                      >>>>> jco@nhm.ac.uk <<<<<
>                  >>>>> "WE ARE JOHN COOPER" <<<<<
>    >>>>> "My name is Legion: for we are many."  St.Mark V:9  <<<<<

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   * Paul Jeffery,       [Curator, non-cephalopod fossil mollusca]      *
   * Room PA205,  Department of Palaeontology,                          *
   * The Natural History Museum, Cromwell Road, London, SW7 5BD, U.K.   *
   * ------------------------------------------------------------------ *
   * Telephone: +44 (0)71 938 8793        Fax: +44 (0)71 938 9277       *
   * INTERNET:  paj@nhm.ac.uk                                           *
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                      >>>>> jco@nhm.ac.uk <<<<<
                  >>>>> "WE ARE JOHN COOPER" <<<<<
    >>>>> "My name is Legion: for we are many."  St.Mark V:9  <<<<<