I spent the better part of 2 hours tonight trying to find research about how often glass should be cleaned, and what is at risk if it isnt. We all know from experience the different things that can be deposited on the surface, but I would like to point my customers to at least one article. I found a good amount of window cleaner sites that state it can damage the glass if they aren’t cleaned enough, clean at least every 6 months, etc. Where did this information come from? Any thoughts? I know we have a niche industry, but there has to be something out there. Thanks in advance for the thoughts!