This was an intriguing letter that recently popped up in the inbox:

Matthew, I noticed in one of your car repair Q&As, you mentioned to use Windex, which under most circumstances contains ammonia. Though it is a good disinfectant and degreaser (having ammonia in it), I've heard it can "dry out," discolor surfaces, etc. and shouldn't be used on automotive glass. What's your take on this? -- Adam

Thanks for having the courage to ask this question Adam.

I've never heard of ammonia being bad for auto glass, nor have I experienced anything like this myself. Our shop works with glass dating back to the 1950s and no ill effects yet. We have found that ammonia will hurt very old (as in ancient) paint jobs if they have already dried out severely, but that's to be expected. If anyone out there has had an experience with an ammonia based cleaner I'd love to hear about it.