Straight Sided Containers:Measure the widest point over which the seal must pass, then add 2mm. For example, if the diameter of the cap is 50mm you should choose a seal of 52mm diameter. Choose a length to suit the purpose but remember the 10% shrinkage which takes place in this direction when the seal is fully dry. |
 |
Conical Containers and More Complex Shapes:In these cases it is important that the difference between the smallest diameter and the largest diameter to be covered by the seal should not exceed 25%. If you are not sure, you should send us a detailed drawing of the product you want to seal. |
 |
Shrinkage on Drying
The seals are made from cellulose and are packed in a mild preservative solution. When you have placed the seal onto your product it dries naturally in the air and as it does so it shrinks down to form a tight seal.
The seals have a total transverse shrinkage of between 35-40%, i.e. it can shrink to two thirds of its original size. The longitudinal shrinkage is around 10%.
NOTE:
For the most satisfactory appearance, you should choose a seal where the maximum transverse shrinkage required of it is 20-25%. If too large a seal is used the shrinkage time can be too long and there is a risk the finish will not be smooth.
