You (OP) may have solved your problem for now. I have sampled numerous ship-loaded parcels of liquid Caustic Soda (Sodium Hydroxide or Potassium Hydroxide).
It is pernicious stuff, highly corrosive to human flesh. Callouses on one's hands may provide a couple of minutes protection, but the backs of one's hands, other exposed flesh will burn in seconds. I always worked with long-sleeves, double (2 of glasses, goggles, or face shield) eye protection, rubber gauntlets when sampling the liquid, and fabric gloves when handling things like hatch covers that supposedly didn't have caustic on them. I washed my hands after each exposure, and invariably my hands were "slimy", indicating there was caustic on them. I carried a 6 - 8 oz. bottle of vinegar to aid in neutralization during hand washing or chance spill. Have a charged water hose nearby.
Also be aware that dilution of caustic soda with water or mixing dry flake with water gives off "heat of hydrolization" that can raise the temperature to near boiling, and be aware the dust/fumes are corrosive if inhaled.