"Closure" refers to the device used to seal your bottle. It will be either a simple screw-on cap or a fine mist spray pump. Closures are distinguished by "type" and "finish." "Type" refers to the way in which the closure attaches to your bottle. "Finish" refers to its size. Your bottles and closures must share the same finish in order to get a proper seal.
Closures can be of three types — screw-on, crimp, and press-on.
If you use a cap to seal your bottle it will be a screw-on. To use the fragrance your customer must unscrew the cap; to seal it, he or she screws the cap back on again. If you used any other type of cap — such as a cap for a soda bottle, once you uncapped the bottle you wouldn't be able to get the cap back on again — you would have to use the whole bottle of perfume or cologne without being able to reseal it!
Like caps, fine mist spray pumps can also be obtained with a screw-on thread. These are commonly used for short runs where the assembly work is being done by hand. Anyone can screw a pump onto a bottle if both are threaded. You don't need a machine to do it.
For a number of years crimp-stye pumps have been the standard for commercial fragrances being produced in quantity. The pump fits over the neck of the bottle and is then crimped — by machine — around a ridge in the bottle's neck.
Purchased in bulk, crimp-style pumps can be considerably cheaper than threaded (screw-on) pumps. It the early days of crimp-style pumps, — fifty or more years ago — the crimped part of the pump could look ugly. Today they look fine. Upscale marketers frequently put a collar around the crimped area of the pump so it doesn't even show.
Crimp-style pumps are generally attached to bottles by machines that fill the bottle, set the pump in place, and then crimp it to the bottle, all automatically. An operator may feed bottles to the machine as the bottles are glass — and breakable — and (unless buying by the ton) generally come packed in boxes that, themselves, do not allow automatic feeding.
Manual crimping machines do exist. They are sometimes called "laboratory models." They are not cheap and they are not perfect. In using them a certain number of bottles may be broken. But it is worth being aware that large, automated machines are not the only tools that can be used to attach crimp-style pumps to bottles.
Press-on style pumps
The same machines that crimp sprays to bottles can also press on "press-on" style pumps. The action of the machine is similar but, for the press-on pump, the "inward" motion is eliminated and the pump is attached by a simple downward thrust.
From your point of view all that matters it that is it is generally done automatically, by machine, and your filling house will have a machine to do it.
"Finish" refers to the neck configuration of bottles and their matching closures. Trade associations have set standards for sizes but not all manufacturers adhere to them. Today sourcing for bottles and closures is global and when buying either bottles or closures, it is important to review samples — or buy both bottle and closure from the same distributor — to insure a secure fit.
Bottles with threaded necks — also referred to as "screw neck" or "continuous threaded neck" — require closures with matching thread sizes.
Threaded finishes are referred to by two numbers, the first indicating the outer diameter of the bottle's neck in millimeters; the second, the thread configuration. Thread configuration is based on how many times the threads pass one another.
Common finishes for threaded bottles and closures would include 13/415 (13mm, 2 thread turns), 15/415 (15mm, 2 thread turns), 20/415 (2mm, 2 thread turns), 24/400 (24mm, 1 thread turn.)
Crimp and press-on
Bottles and closures for crimp and press-on style closures are defined by a single number indicating the outer diameter of the bottle's neck at its widest point in millimeters. The closure will fit over this rim and lock under it. Common sizes for perfume bottles using a crimp or press-on closure include 13mm, 17mm, 18mm, and 20mm.