It is important to identify the jar thread type aswell as the diameter measurement when matching a cap.
1. MEASUREMENTS
To determine the correct size match;
Jars – measure the diameter across the top of the jar, including the thread.
Caps/Lids – measure the inner diameter of the cap.
It’s also important to consider the depth of the jar thread. Most common twist jars have a standard thread depth, while screw-finish jars can vary more widely.
If the thread depth of the jar and cap are not correctly matched, a gap may occur between the top of the jar and the inside of the lid once applied. This can compromise the seal and lead to leaking.
2. THREAD TYPE
There are many different neck ‘finishes’ that determine a bottle or jar’s compatibility with a closure.
The most important factor to consider, especially when reusing bottles or jars at home, is the thread type. The ‘thread’ refers to the rings around the vessel’s neck that the cap secures onto.
Twist jars – Defined by a broken thread (i.e. starting and stopping around the vessel neck). This style is most commonly found in grocery products such as jams, preserves, and olives. It requires a metal twist cap, which features ‘lugs’ that catch onto the thread segments.
Screw jars – Defined by a continuous thread that runs all the way around the neck. This style is more common in cosmetics and requires a screw cap. The cap engages at the top of the thread and twists down to seal.
These lid types are not cross-compatible, so it’s important to correctly identify what you have.
Another type you may encounter is jars without any thread. These are typically designed for use with a metal gasket and clip-top closure, or sealed with a cellophane wrap. We do not supply closures for these types of vessels.
3. CHECKING THE FIT
To assist is getting the right match you can bring your jars into store and check the fit of our caps on display.
If you are not Wellington based then our team is able to assist over the phone, or arrange to send you samples for testing.
If you would like to learn more about replacing jar lids, we have a short video covering the information above, along with examples.