Picked up this little Century Lucite brush, the color is a goldish green. I was able to pull the old knot out by hand, and removed the remaining rubber with a dremel buffing wheel. Now waiting for an 18mm F2 from TGN. I had considered a synthetic, but TGN did not have an 18.
I went all natural, no paint, now I wish I had, but still happy with the brush.
I used a Mercury dime (worth about $2) to lift the knot a bit, and add a cool factor.
The Mercury dime is fantastic! I have one from my paper delivery days in the late 70s. I don't know if I could bring myself to drop it at the bottom of a lucite restore, though.