Evening tone of hot rolled steel

We are building a staircase in our home. The spindles will be made of 1/2 inch hot rolled steel with decorative stained wood balls for interest and aesthetics. We would like to preserve the dark gray tone of the steel but would like to even it at bit and are wondering if there is a product what we can apply to do that. While staining the balls I rubbed some wood stain ⇦ on eBay or Amazon [affil link] onto the steel to see what would happen and that helped somewhat but not sure what the long-term effects or lasting power of that might be. Any product suggestions?

Perhaps try acid etching. ferric chloride ⇦ on eBay or Amazon [affil link] wiped on steel will produce different shades of grey depending on how long the steel is exposed to it. you can buy ferric chloride ⇦ on eBay or Amazon [affil link] at radio shack as PCB etchtant (circuit board etcher). makes sure to wipe down with some sort of base(baking soda [in bulk on eBay or Amazon [affil link] ) after you are done to stop the acid from excess etching.