 Stains can cause your egg to be downgraded to grade B or dirty on exterior grading. Stains can be slight, moderate, or prominent. The stains can also be scattered or localized. Dirty eggs should never be sold. Grade AA or grade A eggs cannot have any stains. For an egg to be considered grade B, a localized stain must be less than 1 32nd of the shell surface, while a scattered stain must be less than 1 16th of the shell surface. Each of these white-shelled eggs has a stain. The first is a slight stain. The second is a moderate stain. And the third is a prominent stain. The first two eggs are considered grade B. The last egg would be considered dirty. Let's look at some brown-shelled eggs. And again with blue-green-shelled eggs. Stains can be buffed out with an egg buffer or fine-grit sandpaper. Do not breathe in the dust created by buffing the egg. It is easier to buff out stains in white-shelled eggs. Buffing stains on a colored eggshell will remove the pigment on the egg's exterior. This makes the eggshell color not uniform and detracts from the overall appearance of your dozen. Can you tell which egg in this dozen has been buffed? How do you avoid losing points for stains on brown or blue-green eggshells? Keep your nest boxes clean. Use fresh shavings or plastic nest box liners. Do not allow hens to sleep or roost in nest boxes at night. Collect eggs three times a day to ensure that you are gathering them at their highest possible quality before refrigeration. Adhering foreign material will cause an egg to be downgraded to dirty. Dirty eggs should not be sold. Fecal material of any size or quantity, feathers, shavings, and even fly droppings will downgrade an egg. Clean eggs well to avoid these problems. On the 4-H Golden Egg score sheet, you will see that one point is deducted for each egg in the dozen that has either stains or adhering foreign material. The adhering foreign material makes the egg dirty.