The short answer
A properly performed repair often makes a chip much less noticeable, but no responsible technician should promise that the damage will vanish. ROLAGS describes windshield repair as removing air from a break and filling the void with cured resin that approximates the glass's refractive index, color and clarity. The standard also recognizes a cosmetic blemish as damage that remains visible after repair.
The result depends on the break type, missing glass, time exposed to contamination or moisture, crack legs and location relative to the driver. Under ROLAGS, the finished repair should be inspected from the driver's position and should not contain significant light scatter, contamination, air pockets or optical defects that could affect vehicle operation. It should also be flush enough not to interfere with the wipers. The practical goals are to add strength to the damaged area, help prevent spreading, restore a smooth surface and improve optical clarity when repair is appropriate.
