Over a year ago I bought the parts to build two heat sticks, and I finally got around to putting them together. I bought two of these
low watt density 1500W elements.
I used them to brew, and they worked beautifully! After the brew, however, I noticed that the elements were now a dull, darker grey. I also went back and looked at the link that I posted above, and saw that they are zinc plated.
I figured that it's probably not good to have that happen, so I found a post on another beverage hobbyist forum explaining how to remove the zinc.
An overnight soak in a citric acid solution, and a couple minutes with a green scrubby, and the elements are down to the copper.
It's all shiny copper, the darkness, especially near the base, is just shadow. I didn't have time to set up proper lighting this morning.