Frequently Asked Questions and User Issues

How tight is tight? And when is it too tight?

A correctly crimped vial is neither over-crimped nor under-crimped. Over-crimping may cause coring or poor septum resealing, while under-crimping can cause evaporation problems.

With proper adjustment, a tight seal can be achieved every time. In most cases, when the vial is crimped perfectly, the cap should not be able to rotate and the septum should appear smooth and level.

Note: The smaller vials and seals will normally have a more pronounced crown or dome effect when the seal is crimped when compared to the 20mm and larger sizes. An indication that the seal is over-crimped will be coring of the stopper or septa, or there may be indentations on the side of the seal or skirt. Another consideration when determining the tightness of a seal is the stopper or septa material. If the stopper or septa material is Teflon, it is likely that the seal can still be turned, even when it is over crimped.

There are many factors that will affect the seal crimp, such as length of the skirt, the thickness, and rigidity of the stopper, the stopper, or septa material. The type of lip or mouth on the vial. (For instance, flat vs. beveled). How well the components fit together, etc.

The side of the cap is denting when it is crimped onto the vial

Are you using the right crimper for the seal being crimped? For example, a 20mm flip-off crimper will not work for a standard 20mm seal.

Am I crimping the vial too far?

The seal may be over crimped, or too far. Try backing off on the distance or pressure the cap is being crimped at.

The cap looks crooked.

The seal may be crooked. The crimper jaws will correct for this in most situations, by centering and straitening the seal during the crimp process. However, if the cap is handing off the stopper alt more on one side than the other, the jaws may not center and straighten the seal completely.

Over time there will be aluminum or enamel build up on the inside of the jaws, where the seal is formed or wrapped. Normally this occurs after crimping between 1,000 and 3000 seals. If used in a cleanroom environment, the build-up of aluminum occurs much faster and more often, due to the lack of moisture and particulates in the air which acts as a lubricant to some extent. To check to see if there is aluminum or enamel build-up on the jaws, use a swab to wipe the inside radius of the jaws. If the swab has a grey tone to it after wiping, the jaws will need to be cleaned, using a swab and alcohol. It is then recommended that cleanroom or food-grade grease be wiped inside the jaws. A thin film is all that is needed.

Are you crimping in a clean room environment?

When used inside a cleanroom or hooded environment, you may begin to see a degradation in the finished crimped seal. In an ambient environment, there is moisture along with dust particulates in the air. The dust particulates and moisture in the air act as a lubricant. ((Continual rubbing, or wearing of aluminum as it is formed, will begin to cause a build-up a combination of lacquer and possibly aluminum particulates. (The crimp seals are normally processed with a film or coating when they are manufactured.) )

It will be necessary to clean and lubricate the crimper jaws periodically. (See preventative maintenance or care)

How do I tell what crimper I need?

Measure the inside diameter of the seal to determine the size. The type can be determined by visual comparison on the crimp seal cross reference chart. See the Cap Sizes & Styles page for more information.