Help With Odd Stain


A customer sent me this image asking for help, I’m told it is a “tin foil” stain. Not sure what that means but this is what he needs to remove from a window. Anyone come across this? If so, what did you use to remove it.



I don’t know, it looks like a monkey fighting a giraffe. Is it on the surface of the glass?


I’m waiting on more details.


To me, it looks like adhesive off the back of Mylar sticker.

If it was really tin foil, I wouldn’t know other than oxidization off old tin foil. But being black like it is, my guess is adhesive off a Mylar type sticker.

After they have been off the window for awhile, I’ve seen them turn that black color.


Looks like the tar from flashing tape to me. Goo gone or a razor can get it, just be aware that goo gone may spread it first.


I see an Elephant on the bottom right side!


If it was actually tin foil maybe it caused a reaction with the low e coating?


I have a really hard time imagining that aluminum foil would react with the low e coating. If low e had a reaction with aluminum, they likely would not be able to use it in window construction. As far as metal transfer (like when someone slides an aluminum ladder against a window) it would not have a pattern like in your picture.

Do you know if there is texture to the stain?


If you clean it and that part that looks like it might be Jesus sheds a tear, you have the most important religious discovery since He was found on a potato chip a few years ago


Aluminum foil on the glass that is exposed to direct sun could have a baked on chemical reaction. I assume that there is no window tint either from after market or from the manufacturer?
Two things come to mind:

  1. Testing a small section with gutter cleaner might bring desirable results? I would just explain to the customer that if it is etched into surface of the glass restoring compounds might need to be used.
  2. Check with the manufacturer if possible to inquire about any coatings or particulars about the glass product they used to glean from them what needs to be done.


Try a very light rub using a cerium oxide in water slurry with a blue huck. Definetly check to see if there is a low e coating on the first surface. Just to know. But a little cerium should be safe. Definitely more safe then chemicals. And you never want to use a razor on any low e coats.



The first step ^

Then if it’s not low e or coated in anyway, my go to would be.


Thanks for the replies, I’m going to pass along the info


Sorry. Dumped my post. Noticed cerium oxide is big bucks. Not familiar with it. That is for calcium, right? And Henry, WCS, you’re saying this is for sticky stuff too? Thanks for reply as class continues. :thinking:


I use it to buff light scratches too :slight_smile:


There are other products for stick stuff, it depends on what the sticky stuff is.


That I understand. For me, that is the solvent realm. That’s why I said try some Acetone (on A SPECK); NO SMOKING! :rofl: