In Short: All “400” finish closures can and do in fact fit and function on 405 glass finishes.
Now you may ask... if a 400 finish cap fits a 405 finish glass bottle, why is it called 405 and is there a difference in thread profile?
There is a 405 finish, but it is specific to only glass bottles.
A glass bottle with a 405 finish is actually a 400 finish but with a very minor depression at the partings lines of the glass threads. The 405 finish was designated to reflect the depth of this depression at the parting lines, so to avoid abrasion and chaffing on the interior of cap thread.
Remember that even if your measurements for the finish differ, the cap and glass bottle will be a match dimensionally. The finish numbers do not have a difference in dimension – just a difference in thread turns.
Two simple measurements need to be considered when determining the cap and closure. The first measurement is the inner cap’s diameter, which is the measure from one side of the inner wall to the opposite, and the finish.
What is the finish? The finish is the part of the bottle that has the thread turn, which is the number of turns of engagement that the cap can turn on the glass neck.
- A 400 finish is defined as having one complete turn of engagement.
- A 410 finish is defined as having one and a half turns of engagement.
- A 415 finish is defined as having two complete turns of engagement.
If you are not positive about the thread and finish measurements, or the number of turns of engagement, feel free to watch our recent video on How to Measure a Bottle Neck or Cap!