When you want to re-apply a patina to a ring, be sure there is no oil on the ring. Even just touching it once with bare fingers will not allow the chemical reaction as the oil acts as a barrier. Clean the ring with acetone. I like to use the paper blue shop towels. These are actually very clean towels to use. Place the ring into your black max or other patina solution without touching it with bare fingers or anything with oil on it. I let it soak for a few minutes.
Here are my steps when applying a new patina, or even reapplying. I use the Sally’s Beauty Supply Miracle buffing block with the white and grey side. I use the grey side to remove any fire scale on the ring and then buff with the white side. I’ll then clean the ring with acetone, apply the patina with black max. Once the ring is black, I will then buff the patina with the white side to a high black shine. This seem to “set” the patina a little more. I’ll then remove the patina from the high points of the detail with the grey side and finish with one last buff on the white side all over the ring.
Here is the link to the buffing block: