The mass production of eggs is essential if the consumer demand is to be met. The egg industry is a highly developed and technical industry. To achieve success, the producer must be something of a scientist, a nutritionist, an engineer and a businessman. On a modern poultry farm, eggs are gathered daily. They are then graded according to quality and weight. The quality of the eggs is determined by means of the candling method without having to break the shell. Each egg rotates under a harsh light. The quality of the egg yolk the white and the air space are monitored and eggs that don’t conform to requirements are thrown out. Blood and meat specks are abnormalities that are shown up by the light. Normally these eggs don't reach the consumer, but should egg with small specks on the yolk and white slip through, it is important to remember that these are harmless and have no effect on the use of the eggs. The quality of an egg is determined by the size of the air space. As the egg deteriorates, the air space expands. Thus placing it in a bowl of salt water can test the freshness of an egg. The fresh egg will lie on its side on the bottom, an egg one week old will lie on the bottom at an angle and eggs of two to three weeks will stand upright. When breaking open a fresh egg, the yolk will form a nice firm dome while the egg white will lie stiff and firm around the yolk. When the egg is not as fresh, the yolk will appear flat and the white will appear watery. When eggs are older than three weeks, the membrane around the yolk tears and the yolk spreads. The white is completely watery. The sizes in which eggs are marketed are as follows: - EXTRA LARGE Eggs with a mass of 59g to 66g (red) - LARGE Eggs with a mass of 51g to 59g (blue) - MEDIUM Eggs with a mass of 43g to 51g (green) - SMALL Eggs with a mass of 35g to 43g (black) Although JUMBO eggs (purple) are found in the trade, the mass group is not officially defined. These are usually eggs weighing more than 66g. These grade standards are set and enforced by the Directorate of Agricultural Product Standards. Inspectors of the Directorate follow up all complaints with regard to egg mass.