Back with another Flyer question - I know that the earliest S gauge link couplers didn't have weights attached and were prone to come uncoupled. It appears that weights were later added to help keep the cars coupled; I've seen references to brass weights (which look like the earliest type of weight), and then references are made to black weights. I looked in my small Flyer parts stash and found a link coupler truck with nickel journal covers that at first glance has a black weight. A closer look shows that it appears to be a weight made of brass with some form of blackening applied. Now comes the question(s) - are all link coupler weights made of brass or are only some made of brass, am I imagining the weight on the truck I have is brass with blackening, and if the weights were made of different types of metal then what types of metal were used?