Hi Emily,

I produced a paper on the subject of micro-slide mounting media back in
1997 Biology Curator Issue 10 Supplement which can be found on the
NatSCA website at
http://natsca.myspecies.info/sites/natsca.myspecies.info/files/The_Biolo
gy_Curator_Issue_10_Supp.pdf. Gum chloral comes in many forms and we at
the Natural History Museum have had problems with crystalization due to
evaporation of water and blackening due to the use of phenol in the
recipe of our gum chloral mounts. So the archival quality of gum chloral
media is in question! The 'Hoyers' gum chloral with a suitably water
tight ringing medium has been used by Anne Baker , our Mite expert who
makes her own without any signs of deterioration as yet. Her recipe is
:-
Crystalline gum Arabic/acacia	30 parts
Chloral hydrate 			200 parts
Glycerol				20 parts
Distilled water 			50 parts
and filtered.

We may not be told what is constituent in 'off the shelf' manufactured
gum chloral media so we might not be able to predict it's long term
conservation performance!

There are some interesting comments on Gum chloral at
http://www.nhm.ac.uk/hosted_sites/acarology/archive/summary.html


Best wishes

Paul A Brown 


-----Original Message-----
From: The Natural Science Collections Association discussion list
[mailto:[log in to unmask]] On Behalf Of David Notton
Sent: 02 September 2009 11:14
To: [log in to unmask]
Subject: Re: Gum Chloral

Hi Emily

Gum tragacanth has been commonly used to glue specimens (usually
beetles) to card mounts, whereas gum chloral has been used to mount
specimens on glass microscope slides, so it depends what kind of
preparation is required.

Be aware that most gum chlorals type mountants (e.g. Berlese) can only
be regarded as temporary. There are a wide range of formulations almost
all of which have problems reported (crystalisation, blackening etc.)
which may damage the specimen and make the preparation unusable without
time consuming remounting. The formulae or proprietry brands are not
usually revealed and can vary.

For long term mounting of insects on microscope slides recommended
mountants are Canada Balsam or Euparal.

Best regards

David
David Notton

-----Original Message-----
From: The Natural Science Collections Association discussion list
[mailto:[log in to unmask]] On Behalf Of Angela Smith
Sent: 01 September 2009 08:51
To: [log in to unmask]
Subject: Re: Gum Chloral

Hi Emily

Watkins and Doncaster sell tragacanth gum in small bottles. I'm not an
entomologist but I've been told this can be used for mounting small
specimens, although you might want to contact W & D to confirm this.
They have a website and sell a lot of useful entomological things - I am
sure they will be able to help you.

Best wishes
Angela



-----Original Message-----
From: The Natural Science Collections Association discussion list
[mailto:[log in to unmask]]On Behalf Of Emily Mayer
Sent: 30 August 2009 21:08
To: [log in to unmask]
Subject: Gum Chloral


The Guild of Taxidermists has had a query through the website from
somebody
wishing to purchase a small amount of gum chloral for mounting small
insect
and invertebrate specimens.
Can anyone advise where he might be able to purchase this? Or whether
there
is a suitable alternative if it's unobtainable.
Thanks
Emily

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