the tint in factory glass isn't baked on, its added to the glass when in a liquid state, the clear liquid glass is dyed that color. it can never be removed through any process. there are ways to bake tint onto glass but they don't apply to car windows, its for commercial or flat glass as we call it, laminating, vapor depositing , sputtering, glazing are just some of the types but these are not removable either, you'd ruin the glass trying to remove them. window films on the other can be removed because they don't become part of the glass's integrity