Okay. I'm a little embarrassed to post these pictures for all to see. This is my stove hood filter.
In my defense, we had some brick work done in the kitchen and the brick dust stuck to the oil, making it look even worse. Gross!
I've tried scrubbing it, but that oil is really hard to get off. I hate washing normal dishes. Washing this was a hundred times worse.
All you need is a big pot and some baking soda! NO SCRUBBING!!!!
Fill your biggest pot with water. Just as it comes to a boil, add 1/2 cup baking soda.
You probably don't have a pot big enough for your whole filter, so just boil half and then turn it over and boil the other side. Here is a picture of my filter in the pot. You can already start to see the water getting dirty!
After a few minutes, and NO SCRUBBING, this is what my filter looked like. See that nasty stuff on the left side? That was the part sticking out of the water. See the right side? It's COMPLETELY CLEAN!