I have no idea what it is, don't think it is because of the blade. maybe its a pollution thing.
been doing serious wiper abuse lately here near seattle.

 

Ordered them for my lancer, the anco's i have on there now dont work to good, but the 3 doller wipers on the truck work great go figure.

 

The wipers came in this morning before i left to go to school, put them on before i left. Got to school and kept wishing it would rain so i could try them out. When my last class was over with and i left school it started to rain as i got onto the interstate and kept pouring harder and harder. The whole time my wipers were working great. Now i just hope they stay performing this great and last for a long time (the set i took off my car were 1.5 years old).