is the scratching of bottles caused by bottle-to-bottle and bottle-to-guides rubbing on the bottling line. Particularly returnable, reusable bottles may pass through a bottling line some 20 to 50 times before they break. Every time they return to the brewery, their labels are scraped off. Then they are washed, refilled, capped, and crated. Eventually, they develop very noticeable scuff rings at the bottle height where they are in contact with the guide rails of the filling and packaging system. Aesthetics is subjective, but Europeans seem to be willing to accept the unsightly, “used” look of a scuffed beer bottle, whereas North Americans might not. Bottle manufacturers use various protective coatings, some made of organic compounds, to enhance their bottles’ smoothness and abrasion resistance, and thus minimize scratch marks. But scuffing cannot be avoided entirely, especially if the bottles are subjected to a cleaning cycle with caustic solutions. This is because the alkaline cleaning agent eventually damages their organic protective coatings. Some manufacturers, therefore, coat their bottles with tin oxide, which is more resistant than organic coatings to removal by alkaline solutions. Scuff marks are also ideal places for bottle bloom.

See also bloom.