I'm partnered with a jewelry production company whose plating baths require KOH. We're located in Indonesia, where import fees are absurdly high, and reliable suppliers are rare. A local shop sells KOH at \$5 / Kg, but whatever impurities are present in their mix cause enough problems to spoil the entire bath. (Expensive mistake when doing gold plating...) The only alternative we can find is a Merck redistributor, who sells KOH at close to $100/Kg, which is ridiculous.
Is there a relatively simple process we could learn (of the DIY variety) for removing impurities, turning non-lab-grade KOH into lab-grade KOH?