Polymerized Oil or Burned Oil? I bought a carbon steel frying pan. Now I need to season it. 
I think i messed up the first time. So I scrubbed it clean again.
Now how do I now if my oil is polymerized or actually burned? 

I heated a thin layer of flaxseed oil until it reached its smoking point and then let it cool and repeat. The coating was really black in the center of the pan and not so smooth. The edges around the center were smooth and golden brown and had a glossy finish. 

Did I burn oil in the center and polymerized the edges?
There is no clear cut border between polymerized and burnt, it is a continuum. The center went clearly farther than the sides, which is common enough in stovetop seasoning. 

If the coating in the middle of the pan doesn't work well for you, you can strip and reseason to a lighter state, preferably in an oven. If food cooks well on it, you can keep it as it is.