Hi All,
I'm glad to share a source I've found for Thompson leaded flux. I've tested it and it works well with the vintage Thompson enamels I have. I realize there are always concerns when dealing with enamels/fluxes that are this old, however this seems to have been stored well. The source is an ebay seller and here is the link:
http://cgi.ebay.com/Enamel-Flux-Powder-Oz-U-Choose-Quantity-/120597188163?pt=LH_DefaultDomain_0The price is very reasonable, too!
Cheers,
Diana