If you go too far, it is irreversable because the steel will be pitted too far to remove without a major re-finish. When I want just a light pitting, I will do 2, or 3 complete processes at only about 3 minutes per, 4 minutes max., until I get what I want, or am afraid to go again. Laurel Mt. barrel brown is much easier to control for a light fine pitting. The LM brown likes a surface of about 220 grit, or just a tad finer. When I used to use it, I put the knife in a humidity box that had a bowl of water in the bottom. Start in the morning with a good coat, refresh it before bed, clean off with wet 220 in the morning, and see what you have. Do not card in between coats! The directions on the bottle say to, but that is for barrel finishing, and not for ageing. I will say, this ageing thing is not for the squemish. I don't always get what I'm after, but usually pretty close at worst. My usual final cleanup is wet 220, lengthwise, to get the major crud off, then wet 400. Then I reblue it and dry rub with 400 on semi hard eraser. This leaves the pits darker and surface grayish. With the knife shown, after the wet 400, I just let it sit over night witout doing any more than a quick wipe with a paper towel. It had a fine, light coat of rust on it in the morning, and a more even finish after the dry 400 rub.