Beverage & Packaging Sealings - 21st Edition: Pull-Ring Cap or Ring-Pull Cap.

Normal Crown Caps (used on Glass bottles of Carbonated Soft Drinks or Beer Bottles; always need an opener. And finding/ keeping an opener easily accessible in all circumstances/ situations (particularly when we are “on the Go” is not so easy. See below Picture for Pry-Off crown:

So what to do when we are not at home or in a restaurant with an easy access to Opener? How can we still enjoy our favorable drinks without having an “Opener” around us??

To address above challenges, Following alternative solutions evolved over past decades in order to overcome this situation:

First one was to have a “Twist-Off’ Crown Cap, instead of a normal (Pry-Off) crown-Cap. The look & geometry of twist-Off crown remain similar to the Pry-Off crown; however here following are the changes/ differences between the two:

1.????? Liner profiles are different. Pry-Off crown liner profiles are designed to have maximum contact area between liner and bottle mouth brim; Whereas Twist-Off crown liner profile is designed to have it minimum possible, in order to have reduce the friction during crown opening. As the Twist-Off crown is rotated by hand/Thumb and finger; hence lesser torque is always safer to avoid injury to hand/thumb/finger.

2.????? Glass Bottle neck profiles are different for Twist-Off crowns. In fact Twist-Off crown has a 3-start thread geometry. When crown is crimped onto twist-off bottle neck; that 3-start thread is replicated into crown as well which facilitate opening of crown by rotating applied crown by hand.

3.????? Use of different liner compounds for these 2 Crown caps. See below picture for Twist-Off crown:

Opening of Twist-Off Crown caps (due to the fact that these metallic crown cap having corrugations, have to be rotated by hand) were not so convenient for opening by children and elderly people and also sometime poses risk of pinching/injuries. Hence the search for further safer caps were continued and this led to the invention of So Called “Pull-Ring Caps) to replace these “Pry-Off” & “Twist-Off” Crown caps. These caps are called with many names like “Easy-Pull Caps”, “Pull-Off caps”, “Rip Cap”, “Ring-Pull Cap” or “Pull-Ring Cap”. Main feature/ USP of these caps is that these caps can be opened without any opener.

As suggested by nomenclature, these caps have a ring, that can be pulled using a finger. These caps have “scores” on the top surface.? So on pulling the ring, cap is split (cut into) into parts by tearing off along the score-lines; hence loosening the grip on the Bottle neck and coming out easily with the ring. The first few milestone in this direction were the caps with a metallic ring rivetted /attached to the cap.

First example of such solutions came as ABE’s Crown Cap / Easy Pull Cap: This cap had a long U shape scoring on the Top of the Cap – bottom of U at the center and 2 arms of U extending towards periphery one of this U-arm had scoring thoroughly hence splitting the cap whereas other U-arm has an unscored portion towards periphery that allows crown to come out along with the ring. In the cap a circular metallic ring was attached to top panel of Crown cap at the Centre. Pulling this ring upward, initiates tearing-off of U-shape strip hence opening of cap in the process. ?See below pictures for clarity:

Easy Pull Crown Caps are shown in below images:

In following sketch/Image, it is explained how to open these caps:

In 1974 AB Wicanders Korkfabriker of Sweden patented the MaxiCap. This cap has a metallic ring attached to this aluminium cap and was produced in 1979 at Wicanders’ factory in H?meenlinna Finland, now known as Finn-Korkki Oy.?A MaxiCap is an aluminium closure with scoring and a tab to pull. See below Pic:

Ring-Pull caps with metallic Ring well accepted for their convenience and functionality; however, the metal ring still created an apprehension for safety of finger; hence the next in the evolution were the Present day’s Rill-Pull cap with Plastic ring. See below picture:

In next article, we shall go into the details of Ring-Pull Crown Cap manufacturing process.