Hoping someone here has some leads...
I am doing some research on blue ink used on banknotes in and around the civil war era, and I came across this site.  Here are a few possible claims I am researching:
Printers still wince at blue ink, and for sure they did back in the 19th century.
1. Blue Ink was new tech in mid 1800s2. It was more expensive to produce3. The chemistry of early ink reacted with paper and/or fabric differently than other colors4. Old blue ink oxidizes5. Old blue ink reacts with UV light and air and fades in color (CSA Blue Backs!)6. Blue ink takes longer to dry, and is easier to smear when not all the way dry7. Blue ink is porous, and thus attracts moisture and never really dries8. Blue ink can be washed out of bills without hurting black ink, making it easy to counterfeit9. Blue ink tech and chemistry changed in late 1800s10. ABNCo started using a lot more blue ink in from 1900-1975, so there was a change in formula and tech. 
  I need to chat with an expert to confirm or deny these claims, or be directed towards the answers I seek.  Thanks in advance.
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Try this ANA affiliated club:
Email info@currencyclubofchestercounty.org   Website http://www.currencyclubofchestercounty.org 

Thank you!  I will contact them and look into it.

Might be derived from those butterflies they were collecting in French Guyana. I learned about it reading the book Papillion by  Henri Charriere