This happens on my car, but it could happen in any home window. Therefore, I post here.
My car has some unknown sticky dirt on the window. I have no clue what it is. I can remove some of the dirt by my finger nail but not completely. I tried to use wet paper towel but does not remove any at all.
Note: I took two pictures. One is from the inside of the car. The other one is from outside of the car.
Hard to tell from just a photo, but tree sap often causes this kind of residue when dirt or dust gets into it.
To remove, try each one at a time until one works, in the following order:
The first one is the least likely to damage your finish or plastics, the last the most likely. If it's a modern car with a base coat/clear coat system, none of the above solvents should do the paint any harm, but the acetone could affect any finished or coated plastics.
If it's on the window glass the simplest way to remove any foreign substance without the risk of harsh chemicals , is with a single edged razor blade. If you install the blade in a retractable holder you can extend the reach of the blade. Hold the blade at a 25-40 degree angle.
