Many herbs will interact with metals and be rendered ineffective. If you're using herbs for medicinal purposes it is better to prepare them in clay or glass and use a cloth strainer...you can usually find these at health food stores...or you can strain it through a coffee filter. Since it is a bark you may need to boil it rather than just brew it like regular tea...can't remember for sure. I noticed a slight metallic taste to it as well...I think it's just the nature of the herb.