Putter Blackening

Doing a search, I see that there have been several discussions in the past regarding putter blackening, but I can't find any recent. So, starting a new one.

I have an old Ping Pal 4 putter that I thought would be fun to refinish and make it black. I did some research online and bought the Caswell SS Blackener. I followed the directions that I had obtained from watching videos, but there were a couple of unexpected differences. First, I sanded the entire putter surface to remove all of the dings and scratches. I then polished it to a mirror finish because I read somewhere that the blackener responded best to a polished surface. It looked pretty sharp, but I did not want a shiny putter. Here is the first unexpected difference. I have seen a couple of guys that recommended dipping the SS putter in muriatic acid for a few minutes to etch the surface before cleaning in distilled water and blackening. I dipped my putter in muriatic acid for a few minutes and it did nothing to the putter, so I just left it in the acid and checked it periodically to see what would happen. After about 6 or 7 hours it did finally etch the surface. Again, it looked really sharp with a nice even very light etching on the surface, but I really wanted the putter head to be black. In hind sight, I should have stopped here. Here is the second unexpected difference. I dipped the putter head in the blackener for about 4-5 minutes and took it out to rinse. It did blacken most of the putter, but it was a very blotchy uneven coloring. I repeated that process several times, but I never got an even finish. I even lightly rubbed with 0000 steel wool as suggested in other discussions to try to even out the finish. Because it looked so bad I left it in the blackener for 15 - 20 minutes or so hoping it would get better. To my dismay, it badly pitted the putter. Like to the point that I might lose the stamped lettering on the putter if I were to start over and sand out all of the pitting. I was expecting more of a bluing type or stain type finish, but it was more like a crust on the surface. When I scrubbed it all off, I found the pitting.

I am just trying to figure out what went wrong or what the issue may be. Maybe the putter is really not stainless steel. It does attract a magnet, but I have read that some SS will attract a magnet. Also, after sanding and polishing, it did have the bright stainless steel look. Does anyone have any insight or suggestions?