I have toyed with several different batches...the first were with cider vinegar and steel wool. I also tried degreasing steel wool. In both cases the results were acceptable but certainly not red-brown. Under the right light, they looked grey. I then turned to rusty South Dakota barbed wire which I have been brewing for months. The concoction looks like stain and went on a test strip of maple dark brown. It also seemed to highlight any curl. Right next to it I tried Aqua Fortis followed by heat to the Aqua Fortis but not to the vinegar. The initial results were not greatly different...both were brown with perhaps more red to the AF. I finshed both with a beeswax/ BLO/ Turpentine paste. The following day, the AF area remained red-brown. The vinegar area had a grey component depending on the light. While I am leaning toward AF currently, perhaps I should consider trying the heat on the vinegar. On the other hand, perhaps even the rusty SoDak barbed wire I found in the pasture had some zinc in it?