Notes for our customers about the products

Dear customers,

You are the focus of our daily work. The following instructions should help you with the selection and the use of our bottle closures.



Many components are responsible for a successful locking of a bottle: T-stoppers, bottles, filling, storage, transport and environmental impact.
T-stoppers are available in many different variations, both with wooden cap and plastic cap. Every variation has different advantages in the area of application. Please contact us for further information!

The diameter of the stopper depends on the material and the dimension of the stopper (synthetic plastic / natural cork). Plastic stoppers have to be 0.5 – 1 mm bigger; cork stoppers have to be 0.5 – 1.5 mm bigger than the bottleneck.

Every glued T-stopper consists out of 2 components, the hold out of wood or plastic and the stopper out of plastic or cork. It is very important that the stopper will be removed with a simultaneous rotation and pulling movement otherwise there will be an urgent risk of breaking the cork stopper away from the hold.

Furthermore we would like you to consider that cork is a natural product and the risk of impairments of changes of the colour of the product cannot be eliminated for 100%.


The interaction of bottle and T-stopper is very important for the leak tightness.

There are no DIN standards in the production of special bottles so there can be tolerances in the diameter of the bottleneck up to ± 0.5 mm. This is the reason why we cannot guarantee a consistent leak tightness of the stopper.

The bottleneck has to be cylindrical up to a depth of at least 15-20 mm with a tolerance of ± 0.3 mm to provide a consistent area for the contact pressure of the stopper.

It is very adverse for the leak tightness if the bottleneck runs bigger in the depth. On the other hand, the stopper can be pushed out of the bottle if the bottleneck runs tighter.

Stopper can be pushed out
Very adverse because not much area for leak tightness

Mentioned below, you can find two measurements of a bottleneck from a favourable and an adverse bottle.
The tables at the end of the page document the data of the measurements.

Favourable bottleneck

Adverse bottleneck

To tighten the bottle, the stopper has to put a certain contact pressure to the bottleneck up to a depth of approx. 15 mm. According to experience, the bottleneck runs bigger into the direction of the bottle form and a longer stopper increases the internal pressure unnecessary.

We are pleased to offer you a free measurement of the bottleneck to find the perfect stopper!

Filling / storage / transport / environmental influences

During the filling, it is very important to regard the correct filling height and to maintain an adequate space between the filling and the stopper. This is very important because of the rising of the internal pressure resulting out of thermal fluctuation. The effect is a volume dilatation of the filling and the increasing risk of the stopper of popping out of the bottle and leakage of the filling.
If oil, cosmetics or liqueurs are filled it is possible that a wet film occurs at the inside of the bottleneck. This is the reason why the stopper can pop out of the bottle by the capillarity.
Capillarity is a characteristic of liquids to spread out in tight cracks or tubes.

After the filling, the bottle has to remain upright to let the stopper reset itself and provide a certain contact pressure to the bottleneck.

Generally, every bottle closed with a T-stopper is only suitable for upright storage.

We reccomend a storage under dry and clean conditions at room temperature
It is very important to not expose wooden T-stoppers to extreme temperature fluctuations. This is the reason why they are not suitable for storage under freezing temperatures. The condensed water could enter into the wooden cap.

Natural products like wooden caps have to be secured from humidity. If humidity ingresses into the wood a natural process starts a deformation which leads to the detachment of the stopper.

The glued T-stoppers should be used within one year.

We would like to indicate that the colour from lacquered wooden caps can disperse by ingress of humidity.

We do not know your needs, circumstances, filling, filling container / bottle, filling temperature or filling method so we recommend to perform some own tests.

In general, a professional counsel from our house is recommendable at every time. We are pleased to answer your questions!

These statements are not exhaustive.

Your Newkork-Team!


Do you have questions?

Please contact us!