Before a DERBYSTAR ball lands on the pitch for the first time, it is tested by us ‘on heart and kidneys’. In case a ball does not meet our strict and high criteria, it is segregated mercilessly, therewith preventing it from ever enjoying being kicked or headed into a goal.
If the football is not perfectly round, it will not roll well on the surface and it will make dribbling more difficult. For this reason step 1 in the FIFA Quality Test is to measure the roundness of the ball. The diameter of the ball is measured on 10 different spots, from which the circumference is calculated.
Balls with the FIFA INSPECTED* logo must have a circumference of 68-70 cm, FIFA APPROVED balls a circumference of 68.5-69.5 cm.
2. Permanent Roundness
If the ball is not completely round, it cannot develop a perfect flight path. This implies that a shot, even if and when exactly targeted at the goal, may miss the goal. To check on the roundness, the ball is measured on 16 different spots, after which the average diameter is calculated.
The difference between the highest and lowest score may not exceed 2% to allow the FIFA INSPECTED* logo and 1.5% for the FIFA APPROVED logo.
At a temperature of 20 degrees Celsius, the FIFA INSPECTED* balls should have a bouncing radius of between 125 and 155 cm.
For FIFA APPROVED balls this should be between 135 and 155 cm.
This test is performed by bouncing the ball ten times on a steel plate, from a height of 2 meters.
4. Water Absorption
In order to ensure that the ball keeps the same playing performance in wet weather conditions as with dry conditions, there is a special FIFA Water Absorption Test. With this test the ball, whilst continuously being turned, is pressed 250 times in a water-filled container.
A ball with the FIFA INSPECTED* logo may not take up more than 15% of its weight at dry conditions and a FIFA APPROVED ball not more than 10%.
5. Perfect Weight
One of the most important features of the ball where a football player should be able to rely on, is the correct weight of the football. With this test the ball is weighted three times in a closed container. This container is sealed off in such a way, that no draft of air can influence the scale.
To be entitled to carry the FIFA INSPECTED* logo, a ball should have a weight between 410 and 450 gram, for the FIFA APPROVED logo a weight of between 420 and 445 gram is required.
6. Loss Of Pressure
With a ball which loses air during the game, it is difficult to give a high and long pass. With the FIFA Test the ball is therefore inflated to a normal default value.
Within 72 hours a FIFA INSPECTED* ball should not lose more than 25% of its air pressure; for a FIFA APPROVED ball the limit is 20%.
7. Stability Of Form and Size
All FIFA APPROVED balls must have passed one additional test.
This test examines whether the form, the size and the air pressure remain stable during the play.
To ensure this the ball is shot 2,000 times against a steel plate, with a speed of 50 km/h. The seams and the valve should thereby remain intact. Only a minimum change in form, size and air pressure is permitted.
* Quality-wise identical to the International Match ball Standard (IMS)