Cleaning out a window

I had a case of a side casting from an O Scale W car kit where the hole for the glazing on the reverse side wasn’t even all ‘round. What this means is when I glaze the car much further along, the glazing edges will be very visible, this looks terrible.

The fix is to route out the recess to allow glazing to sit, and not see the edges through the window. I have always found this process hard to explain, I’m hoping the couple of images show what needs to be done.

Another little thing I watch for is bubbles, and as luck would have it, I got one right in the middle of a window frame. The only way to fix this is to cut out the entire frame side and replace with a length of styrene strip. This is not a job for putty.