After several years of research involving both empirical staining and 
theoretical deductions from molecular modeling, we have found direct 
red 72 to be superior to Congo red and Sirius red F3B for staining 
amyloid.  This dye produces a better color than Congo red, offering 
improved contrast.  It is birefringent and fluorescent, although we 
have not really felt the need to go to these specialized optical 
methods to visualize tiny deposits.  Both Congo red and Sirius red 
F3B present solubility problems which are much reduced with direct 
red 72.  Finally, we have a highly specific staining protocol that is 
simpler than most Congo red methods.

Anatech Ltd. plans to offer this dye for sale in the United States 
sometime in the next few months.  Directions for solution preparation 
and staining will be included.  Interested parties may contact us 
directly.  To my knowledge, this dye is not available from another 
source in laboratory quantities.

Pagoda red, mentioned by Terry Marshall, is (was?) a Bristish dye 
manufactured by Dylon for home textile dyeing.  Its composition is 
not revealed, but like similar Rit dyes in the USA, it most probably 
is a mixture of acid and direct dyes whose exact composition varied 
from lot to lot to meet changing market demands, if in fact more than 
one batch existed.  I had a 1 gram sample dating back to the 1960's. 
Scattered references in the histological literature may be found, all 
without concrete information.  Apparently someone tried it, it 
worked, and passing mention was made; thus Pagoda red entered the 
scientific realm.

Dick

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