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WHY CONSIDER GLOVE TENSILE STRENGTH AND ELONGATION PROPERTIES?

The skin is an important route for penetration of chemicals or microbiological agents that are potentially dangerous to human health. Thus, wearing disposable gloves is essential for many applications in the laboratory, cleanroom, industrial or medical sectors. It is therefore essential to ensure the protection of workers by providing them with disposable gloves adapted to the tasks being undertaken.

When choosing a single-use glove, considering its tensile strength, elongation properties or even its potential for tearing whilst being stretched may be relevant. Indeed, a glove that tears no longer effectively protects the user. To prevent disposable gloves from tearing it is necessary to ensure that the selected gloves will withstand elongation especially during donning, without altering the qualities of protection, comfort and fit.

 

CHECKING THE TENSILE STRENGTH OF SINGLE-USE GLOVES

 

Depending on the glove material, its physical properties will be different and so will its protective properties. In this respect, it is worth noting that:

 

“Natural latex is usually of higher elasticity than nitrile or vinyl but its protective qualities against chemicals splashes may be lower.”

 

To minimize the risk of tearing, it is advisable to choose gloves based, among other things, on their tensile strength data and elongation properties.

Surprisingly, measurement of physical properties is not a requirement for PPE-type ” protective gloves against chemicals and micro-organisms” (as defined in ISO 374-1:2016+A1:2018 “Terminology and performance requirements”). Therefore, it is useful to refer to the results of the elongation at break and tensile strength tests under the nearest relevant European standard (EN 455-2:2015 for medical gloves) or the American standard ASTM D412-16 (supplemented by ASTM D573-04(2019) for tests after aging).

 

The tensile strength is expressed in Newtons (N) or in megapascals (MPa). A physical deformation test evaluates the amount of force applied to a glove sample until it tears.

  • Test method: samples are cut into the shape of “dumb-bells” or “dog-bone” at the palm, back of the hand or cuff in the longitudinal axis of 13 gloves from the same batch. After conditioning for a minimum of 16 hours, the samples are subjected to a load whose tensile speed must be 500mm/min. The thickness of each sample is then measured and compared to the initial thickness to determine a value.

 

Pictures of disposable glove samples and tensile strength and elongation test

 

  • Test results: The median value of the results recorded shall comply to those indicated in European standard EN 455-2:2015 which are > 9.0 N for surgical gloves and > 6.0 N for examination and care gloves regardless of the material except for thermoplastic gloves (polyvinyl chloride for example) for which a median value of > 3.6 is indicated. (The minimum tensile strength values, expressed in megapascals (MPa) and specified in ASTM D412-16, are between 14MPa and 24 MPa depending on the glove material).

 

Elongation performance is expressed as a percentage (%) of the initial length of a sample. Minimum elongation values required in the ASTM vary from 300% to 700% depending on the material (the lower percentage corresponding to Vinyl and the highest to the Natural Latex).

Additional tensile strength and elongation performance tests are also performed with samples that have been subjected to accelerated aging to evaluate the physical properties of the glove at its expiration date.

All SHIELD Scientific gloves meet the minimum required values (See SHIELD Scientific Gloves Data Sheets).

 

HOW TO PROPERLY STORE AND DON DISPOSABLE GLOVES

 

Other factors can enhance or alter the properties of a single-use glove relating to the risk of tearing:

 

Compliance with packaging and storage conditions

 

Glove materials may deteriorate if exposed to light, moisture, or certain temperature levels. Therefore, manufacturers must provide recommendations on the storage conditions in the user’s instructions for all their products (mandatory document in accordance with Regulation (EU) 2016/425). The main recommendations are typically:

  • Not to exceed the expiry date of the gloves (this information is a statement that must appear on the packaging, and which is illustrated by the following pictogram Validity pictogram ).
  • Respect the integrity of the packaging (do not pierce or cut plastic packaging, do not crush cardboard packaging…).
  • Store gloves in a dry and cool place (temperature can cause hardening of the material making it less flexible and therefore brittle).
  • Keep gloves away from direct sunlight, intense artificial lights, X-ray machines and other sources of ozone.

It is essential, before use, to inspect the integrity of the packaging as well as the gloves. In case of doubt about the integrity of a glove, it is better not to use it.

 

Thickness and how to don single-use gloves

 

Donning and doffing single-use gloves, several times a day, is part of the daily life of many professionals in the industrial, laboratory, cleanroom, or healthcare sectors. For a glove to protect properly it is necessary to be able to don it without tearing it. The thickness of a disposable glove is also an important element because the thinner a glove, the more fragile it is (do not be fooled).

 

The thinner a glove, the more likely it is to tear whilst stretching it for donning purposes.

 

To avoid tearing a glove when donning, there are some rules which should be respected:

  • Make sure you choose the correct glove size.
  • Dry your hands properly and thoroughly before donning.
  • Do not wear wristwatches or jewelry.
  • Do not don the glove by pulling too close to the rolled edge of the cuff but pull at least 3 cm below the rolled edge to avoid tearing the cuff.

 

bad and good way to don a disposable glove

 

In summary, a glove may be more or less resistant to tearing due to its physical characteristics, with material type or thickness being particularly relevant.

The key point is that “the better the resistance, the less likely the gloves will tear” particularly during donning. Of note is that stronger gloves can lead to fewer gloves changes, thus decreasing the risk of contamination of assays.

However, greater strength can also lead to more difficulty in donning the glove and some stiffness in use. Significant elongation properties avoid the risk of tearing when stretching while facilitating donning and ensuring a better fit, thereby contributing to more comfort and dexterity.

Choosing the correct glove therefore depends on the desired objectives in terms of protection and comfort, whilst maintaining compliance. To conclude, it is important to consider both the properties and physical characteristics of a glove as well as the application for which it is intended to make the right choice.

 

Remember: THE STRONGER THE GLOVES, THE MORE DURABLE THEY ARE IN USE THERBY PROVIDING OPTIMAL PERSONAL PROTECTION.

 

TO HELP YOU SELECT THE GLOVE ADAPTED TO YOUR NEED, USE OUR SHIELD SCIENTIFIC GLOVE SELECTION GUIDE.

 

 

 

This post is also available in: French, German, Spanish

Categorised in: Glove education

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