The wretched snowflake or clouding effect (both descriptions too nice for this nuisance) is the result of the adhesive used on these strips at the factory. It set like concrete but reacted with the plastic forming the window strips. Removing affected strips and the residue of the glue is a real bore; it takes a solvent like Goo Gone to clean it up. It looks like a cellulose-based glue. The replacement windows come with adhesive strips top and bottom. I also like the green glass tint.
There was a thread on this subject a while back. From my own experience the defect may take years to become visible and it can only be dealt with by replacing the affected strips.
