Coatings, and tempered, and low-e, Oh my!


Hey guys,

I’ve been lurking for a while. This is my first post. I’ve benefited greatly from the conversations and advice here. This place is awesome! My wife and I started our business June of last year and have been thrilled with our success thus far. We are definitely still in the early stages of running our business and learning the trade, but we can see our business and skill level growing. Bringing me to the reason for my post.

Obviously, one of the biggest areas of concern for the professional is damaging glass. I’ve utilized the search function to do a little research and make sure we are prepared for different types of glass. but theres one area I need a little help.
P.S: Sorry if I missed an old topic on this.

Yesterday I ran into an issue with some Andersen 100 series 8’x8’ fixed windows. They were labeled as “smartsun, Low-e”. Tempered as well. The home is new construction and recently had the protective covered removed from the window. The scope was to remove the left over, albeit slight, layer of adhesive from the protective cover left on the windows. I tested steel wool on the exterior facing surface and noticed pretty significant and obvious swirling (windows are in direct sunlight). I suspended the use of steel wool and went with a washer with a little more scrubbing power, washing each one multiple times until they were clean. They looked good!..Then onto the inside…after I cleaned them while walking back and forth, I noticed severe vertical lines of haziness that appeared to be in between the panes. In various sizes and patterns all throughout the glass. I guess I have 2 questions:

  1. Low-E: is steel wool known to scratch the exterior facing surface?
  2. could this haziness in between the panes be a sign of faulty tempering? If not, any ideas?
  3. auxiliary question…self cleaning. Is it possible these windows have titanium dioxide on the exterior surface? How do you identify this? Most of the information I found on this topic was a few years old. Are these popular? Steel wool is a no go on this correct?

Thank you guys, please forgive me if I’ve missed any related topics


Provided it was installed correctly then it should not, however if the pane was not then you could have transferred metal onto the coated surface, if this is the case a mild hydrochloric acid solution should remove it.

possibly, but doubtful, its more likely to be an issue with the installers.

Its possible, when doing any CCU, what is important is you consult with the builder/foreman and request the spec sheet for the glass, then you will know exactly what type of glass you are dealing with.


Determine which side of glass the haze is on. If its sealed between then its obvious.


Thanks for the input. The hazing was definitely in between the panes. hadn’t seen that before and was curious.


It is very common for double glazed units to have marks and streaks between the panes. Have a look in direct sunlight. Sealed units are only as clean as the job done by the manufacturers during assembly. They generally use pure water and squeeges on the inner faces.