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Closures &
Neck Finishes
Thread Dimensions
"T" Dimension - outside diameter of the thread width
"E" Dimension - outside diameter of the neck not including the thread. To determine the depth of the threads, subtract the "E" dimension from the "T" dimension and divide by two.
A container's neck finish holds the cap, or closure, with protruding threads. A container and its corresponding cap must have matching finishes.
Screw thread cap sizes are generally expressed as two numbers separated by a hyphen or slash. The first number refers to the cap diameter in millimeters. The second number refers to the height and thread configuration of the closure or finish (ex: 38/400).
To determine the diameter of a closure, measure from the inner wall on one side of the closure to the inner wall on the opposite side. A bottle neck finish can be calculated by measuring the diameter of the furthest outer threads. To establish the finish, verify the number of times the threads pass one another.
"I" Dimension - inner diameter of the neck measured from the inside wall of a container.
"S" Dimension - vertical distance from the top of the finish or sealing surface to the top edge of the first thread. "S" dimension determines the orientation of the closure to the bottle or jar.
"H" Dimension - total height of the neck finish measured from the top of the neck to the shoulder of the bottle
1 Thread
turn
400
1 . 5 Thread turns
410
2 Thread turns
(tall "H")
415
2 Thread turns
(narrow threads)
425