The old chimney top spark arresting screen was worn out.
I happened to have an old Inconel [1] heat treating basket. The mesh on the basket was approximately 3/8 of an inch. The basket was about 9 inches in diameter and about 10 inches long. Since Inconel never wears out, I thought this was the perfect chimney top screen.
I quickly found out - this was a bad idea.
Immediately the screen began to clog with glass like creosote. Within two weeks the entire screen was almost completely clogged with creosote. See the images above.
When you put a screen over a wood stove chimney you want to make sure that you use as much screen as possible and the mesh on the screen is greater than a quarter inch.
The more surface area the screen has the longer it will take for the screen to clog with creosote. If your wood stove has a catalytic converter the screen mesh and surface area is less important.
Enjoy your burn - it's solar energy!