Barry,
We've just started our pw and window cleaning business a couple months ago and have done alot of research into both before we started.(still lots to learn in the pw part of it)Ken just did the windows of a large bed and breakfast house a couple weeks ago(some of the windows were huge!) When I saw the owner in the mall a couple days later, she came up to me and said Wow! Ken sure did a good job,and he even got the hard water stains off, how'd he do that? We have a big house with lots of storm windows(2 on the outside and 4 on the inside for all of them).
We are using the same product we have been using for years on our own windows. Works great for us so decided to stick with it.
Not sure if it's permitted to say the product on here so if you'd care to E-mail us, will most certainly tell you what we use so you can try it and decide for yourself.
Kathy
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Northern Lights Pressurewashing and Windows. Ken/Kathy Erb