Alcian blue indeed is an excellent dye to mark edges of specimens.  I 
just finished a project doing just that to mark posterior margins of 
cross sectional segments of salamander tails.  The dye resists 
processing solvents.

Alcian blue should be available in small lab-sized bottles in the UK 
(and elsewhere) from Sigma and possibly TBS.  In Australia and the 
Pacific Rim, try Pangalark (email them at Pangalark@aol.com).  In the 
US and Canada, Anatech Ltd.

To our knowledge, we are currently the world's sole primary supplier 
of this dye.  It is certified by the Biological Stain Commission 
(BSC).  We sell it in bulk quantities worldwide.  It is expensive 
(regretfully, but that is the price of responsible manufacturing 
practices).  We try to avoid selling retail quantities (25 g bottles) 
outside the US and Canada because the shipping charges are far in 
excess of the dye's price.  As vendors overseas get requests for the 
dye from their customers, they come to us for material in quantity 
sufficient to make shipping costs effective.  Our supply is 
dependably renewable:  4 lots have been made and certified since 
January 2001.

Important note:  Alcian blue 8GX was made by ICI for a very limited 
time.  Many of the batches of Alcian blue from ICI and from later 
manufacturers were not 8GX, but few vendors ever made the 
distinction.  Today, the name Alcian blue 8GX is used for all of them 
(not cool).  Modern Alcian blue is not 8GX.  Other variants differ in 
the placement and number of ionizing groups.  The exact composition 
of 8GX is not known (see Conn's Biological Stains).  Some of the 
variants, such as ours, meet the criteria of the BSC for Alcian blue, 
other variants did not meet the standard; the Commission does not 
certify any Alcian blue dye specifically as 8GX.

How does modern certified Alcian blue compare to older material?  It 
depends on what you have as older material.  Ours is readily and 
essentially completely soluble in water (especially warm water).  It 
is insoluble in anhydrous alcohol and poorly soluble in 70% alcohol, 
hence its suitability as a marking dye during tissue processing.  Dye 
content is higher (60-65% versus 50-55%).  In water, its 
spectrophotometric peak is identical to original 8GX, so colors are 
identical.

Dick

-- 
Richard W. Dapson, Ph.D.
Anatech Ltd.
Battle Creek, MI
800-ANATECH (800-262-8324)
email@anatechltdusa.com
Web address:  anatechltdusa.com