Get the Right Closure for Your Glass & Plastic Packaging with 3 Pointers
1. The cap or lid closure should be dimensionally compatible with the bottle or jar finish.
To get a proper fit, it's important that your cap and container have matching neck finishes.
2. The neck finish on the plastic jar or glass bottle is the template, or guide, for choosing the proper closure.
Neck finish is represented by a pair of numbers separated by a dash. For example, "33-400" is a common neck finish. These numbers give us the dimensions of the lid, or the neck of the container.
3. The cap or lid and the bottle or jar must both be measured.
It's important to look at both your container and your closure, to ensure that they match.
You must know how to find a cap’s diameter, and how to measure the neck finish in order to appropriately pair containers and closures. Use the following steps while letting the diagrams below be your guide:
How to calculate a bottle's neck finish:
Calculate a bottle’s neck finish by:
- Finding "T" Dimension: Major (Outside) Diameter
Measure from the outermost thread one side to the other outermost thread on the other side with a digital caliper for the most accurate measurments. Used to measure for compatible closure. - Finding "H" Dimension: Height/GPI Thread Finish
With a digital caliper, measure from the top of the neck to the point where the diameter "T", extended down, intersects the bottle shoulder. - Putting the "T" and "H" Dimensions Together to Complete the Formula
Using our R70MMP cap and SSJ-8-F jar as an example, 70 mm “T” dimension with 1 thread turn = 70/400 neck finish. The first number (70) refers to the diameter of the closure or bottle opening (in mm) and refers to the nominal diameter measured across the inside of the cap at the opening or the outer diameter of the bottle. The second number (400) represents the GPI thread finish (in inches) and refers to the height of the cap and the style of threads on the cap and the container.
*Note the rest of the bottle finish elements as follows:
E/Minor (inside) diameter: From the innermost side of the thread to the other innermost side. Used to measure for liners and foil seals.
S/Start of thread. From the top of the finish to the top of the thread at the start. Influences thread engagement.
Do you now know which bottle or jar closure you need? Then you’re ready to select the right types of bottle caps for your wholesale glass bottles and jars and plastic bottles and jars.
We've created a helpful PDF with all of this information to assist you in finding the right closure
Still Need Help Selecting the Right Containers and Closures? Contact us today!
With over 75 years in the packaging game, BASCO has seen it all. Even the most niche of industries have trusted us to provide them with the packaging they need, at a price that's fair. We're here five days a week, ready to answer the phone or respond to your emails, and help you find the perfect container for the job. Contact us here if you have any questions!