Keeping a large flock I gave encountered this problem many times so I have developed a few methods to thwart it. Lighting - During long winter months I keep natural light from the hens during the dog days of winter and just provide them artifical red light bulbs. The red glow seems to fool the birds eyes when it comes to blood. Treats Boredom is a major cause of this so I provide turnips and other hard vegetables to keep the birds busy. When they are not able to free range they will peck one another just for the heck of it. Roosters Keeping roosters will always result in feather loss on the backs of your hens. So keeping them separate during long peroids of confinement helps with this problem.Stop-pick When birds do get wounds I apply this stuff to the wound to deter the other birds from pecking the would. I also apply other birds with the stuff to deter the habit in general. Culling Last resort here but if you have a real bad bird it might be just as well to get rid of it so it doesn't start others on the habit.
If you sell eggs the eggs have to be clean as customers will frown on soiled eggs. I clean my eggs with scalding hot water (no soap). I wipe the eggs with a scouring cloth and set them to dry on a clean dry tea towel. If the water starts to get at all dirty I dump it and get fresh scalding water. The eggs will often air dry since I used hot water but if not I wipe them right away with a peice of paper towel.