Pre-Mixed Rhodium Bath 1Gram1 Pint Everything you need is already mixed into each bottle so this solution is ready- to- use as is. Just pour the rhodium into a beaker or tank and you are ready to start plating. For professional use only. Cohler's new Superblack rhodium plating solution is a black rhodium plating solution that produces a darker oxidized grey-black plate on gold and other precious metals than ever before. Use it for a durable tarnish resistant dark finish for all your plating needs. Superblack has a deeper dark finish than the original Cohler black rhodium bath. It works better for matching dark stones or where you just want a darker black plating on your jewelry. Great for two-tone plating and touch up repairs. Plates at room temperature using a platinized titanium anode. This is the pre-mixed ready to use bath plating version of Superblack. It is not a concentrate and it is not suitable for pen plating.