A H3BO3 + MeOH reaction was run at similar to 60 degrees C/1 bar in a 100, 320 or 1250-I. still equipped with a Raschig or Sulzer's BX or Bialecki ring-packed, 200x4500 or 300x6500-mm, 5 or 25-TP column so as to leave 50% of the reactants unconverted. A (similar to 7.3 w/w) Me3BO3-MeOH azeotrope (trade-named Borim) was collected at 51-59 degrees C, activated with 5-7 g/kg KF, and stabilized with 5-7 g/kg ethylene glycol.. As a brazing flux, the Borim provided a broad de-oxidn. zone and ensured the best wettability and spreadability for the Cu301 brazing brass on nonalloyed steel and an Ag hard solder on Cu and brass. Borim's b.p. 52-56 degrees C, d(20) 0.883, and H2O max. 0.05%.