Here a sample of the finish you should look for. The first picture is of a pair of 64-66 strut rods I phosphate a few years back. They are too dark. The second picture is of two 64-66 center links that I did around the same time and they came out a lighter shade. After bead blasting, the technique I use is a smaller amount of phosphoric acid than is specified, about half, and less time, in this case a minute and a half, and as hot, 200F +, as the stove would get the bath. I used a stainless steel fish poaching tank. The rods and links were too long so I started one end in the bath for 15 seconds, then swapped ends every 15 seconds.
Jim