In the packaging industry, the material around the neck opening of containers or the inside dimensions of its closure is referred to as “finish”. The type of finish is seen in a formats like: 20/410 or 20-410. There are two important parts to these formats: the first number refers to the diameter in millimeters and the second number refers to the thread count.
To get these measurements, you will first need to find the diameter (measured in mm).
For a bottle: Measure from the outer edge of the thread on one side to the outer edge of the thread on the opposite side. For example, if the neck measures 24mm, then it requires a 24mm closure as shown below:
For a cap: Measure from the inside wall of the cap to the opposite inside wall as shown below:
If the thread loops around the neck and passes over itself one time, then it is considered a 400 finish. If the thread passes over itself one and a half times, then it is considered a 410 finish. If a thread passes over itself 2 times, it is a 415 finish. Below are examples of the most common thread counts:
We recommend requesting samples and testing bottles with closures before making a purchase.