Pinterest is wonderful. Yesterday I found directions on de-greasing the vent filter the easy way. The instructions said:
Fill your largest pot with water and bring it to a boil. Slowly stir in 1/2 cup baking soda. Do it slowly because it will bubble up for a moment with every addition of baking soda. Then stick your hood fan filter in the pot and let it sit. Turn it end over end, and let the other end sit for awhile. The boiling water literally boils the grease right out, and it comes out sparkling clean!
See how murky the water is? That is all the grease boiling out of the filter.
After it was clean and the water drained off, I had to keep it propped up over the sink all night, but it was still damp in the morning. I clipped it back in place anyway, and it dried eventually.