I worked with Martin et al. and the sodium borate was added to the Paragon 
stain to help the penetration into epon embedded sections.  The Paragon stain 
was designed for frozen sections and was marketed by a company by the name of 
Paragon.  The formula that appeared on the bottles of Paragon stain was as 
follows:
Toluidine blue  CI 520040 ................0.73 gm
Basic fuchsin , CI 42510 ................0.27 g,
Ethyl alcohol, 30% ........................100 ml

If adding sodium borate, it must not be added to the bottle, as it affects 
the stability, but is added to the stain on the slide - only a little pinch.

Hope this helps.

Freida Carson