I've used the "disappearing or invisible" gift wrap tape to model dirty windows with success. Cut a piece of tape that's double the size of the window opening, then fold it in half so that the sticky sides stick together. Brush a thin layer of white glue around the window opening and press the tape into place. You can also use regular tape. But instead of using the folded in half technique, just stick it to the inside of the window opening. Then, apply some white or very light gray weathering powder with a makeup brush. This does two things. First, it gives you the dirty window effect you want. Secondly, it covers the adhesive so bigger things won't stick to the window.
Marlon
See pictures of the Clinton-Golden Valley RR
I love good ideas vs having to buy specialty product.
Richard
A light spray of dullcoat works just as well and is a lot quicker. A great effect for engines and automobiles is to mask the glass where the path of the windshield wipers would be, then give it a shot of dullcoat. The result is that of a dirty windshield with a clean area where the wipers have done their job.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
I used that for a frosted bathroom window on couple of buildings. And I found that clear plastic lids from deli containers give a wavy old glass look. To dirty them up I streak them from the inside with a wash. When I put the wash on the outside it pooled around the details and did not create the streaks I wanted.
Bill
Great concept Medina. Can't wait to try it.
Microscope slide covers work great. First they look like real glass, second you can smudged them up enough with just your own greasy fingers to make them look like they haven't been washed in a while. Just try to install them if you want that clean and shinny look, no matter how many times you wash your hands they still get dirty. Tweezers help in the end.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."