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Although there are four main types of disposable gloves used in the medical field, they are manufactured and tested in similar ways. In this guide, we’ll be going over the different types of disposable medical gloves, how they’re manufactured, and what kind of testing they go through. If you’d like to learn more about how other types of medical supplies are manufactured, you can also check out our comprehensive guide on how PPE is made.
At a glance:
There are four main types of rubber gloves: latex, nitrile, polyvinyl chloride (commonly known as vinyl), and polychloroprene (commonly known as neoprene). Medical gloves can come with coatings or treatments such as polymer coating, but they cannot have powder on them according to FDA guidelines.
Related: Types of Safety Gloves
Whichever material rubber gloves are made of, they are manufactured in the same basic way. The process starts with hand-shaped ceramic or aluminum molds on a conveyor, which are dipped in wash tanks with hot water and chlorine or bleach and then dried. This dipping gets rid of any potential residue from the previous batch of gloves. Once the molds are cleaned, they must be coated to make the rubber stick. To accomplish this the molds are dipped into a mixture of calcium nitrate solution (which will coagulate the rubber) and calcium carbonate (which is a lubricant to keep the gloves from sticking to the mold too much). A second drying occurs, and then the glove forms dip into tanks of either latex, nitrile, or polyvinyl chloride. This is when the processes begin to differ since the materials must be processed differently.
Latex gloves have their thickness determined by how long they remain in the tank. Once the forms are out, they spin to remove excess rubber and then are washed in hot water and chlorine again. This process removes excess latex and chemicals to lower the severity of any allergic reactions. The forms are then dried and cured using vulcanization, which interlinks the rubber molecules to make the gloves stronger. After a second rinse to remove any more excess latex, the gloves go through a series of brushes that roll (also known as beading) their ends into cuffs. They are then removed using air jets. Once they’re off the molds, the gloves can be tested and shipped.
Nitrile or vinyl gloves are also dipped in a tank filled with liquid rubber and baked to form and dry them. Gloves then may undergo chlorination or polymer coating to make them easier to put on and take off. Chlorination, in which they are exposed to chlorine, makes them harder and more slippery. They can also be polymer-coated, which lubricates them. Once any coatings are added, gloves are stripped from the molds, commonly by human workers, since synthetic rubber is stickier than latex. The gloves then can be tested.
There are two types of testing gloves must go through. Firstly, gloves must meet regulatory requirements to be certified as medical grade before they can go onto the market. Once these requirements are met, each batch of gloves is given simpler tests afterward to ensure quality is being maintained.
For batch testing, gloves are tested first by being filled with air, then by using the pinhole leak test according to ASTM standards. Although all gloves have pinholes, the test ensures the pinholes aren’t big enough to allow fluid to reach the skin. Workers fill the gloves with a liter of water and watch for two minutes for leaks. Industrial glove batches have to meet an acceptable quality limit, or AQL, of 2.5%, which statistically means that only 2.5 gloves per 100 can fail the test. Having 1.5 gloves per 100 fail means the gloves are of higher quality and can be used in medical applications.
Besides the tests that must be performed on each glove batch, there are regulatory tests to prove the gloves being manufactured are safe enough to merit a medical rating. All gloves must pass a dimension test, in which the glove must meet requirements for the length between the cuff and middle fingertip and the width of the palm, as well as a certain thickness requirement. These measurements depend on glove size and type. Gloves must also pass sterility tests in line with the guidelines in the U.S. Pharmacopeia, and aging tests, which require a glove to meet tensile and elongation performance standards after being heated at 70 degrees C and 100 degrees C for a certain number of hours. Powder amount must also be less than 2 mg per glove. Latex gloves must also pass additional tests for aqueous extractable protein content and antigenic protein content.
ASTM is currently making its testing standards for PPE available for free to help companies producing vital supplies during the pandemic. You can register to read the standards on their website. The FDA has also temporarily cut down on some of the requirements to approve medical gloves for manufacturing, as long as companies send a premarket 510k notification, the product follows ASTM standards, and the gloves are properly labeled. More information can be found on their website.
This article summarizes the main types of disposable medical gloves, how they’re manufactured, and what tests they are required to pass. If you’re part of a medical or other relevant organization looking to source necessary COVID-19 supplies, we encourage you to sign up for our free critical product matchmaking services. If your company can help with producing these or other PPE products, feel free to sign up for a free listing and be vetted as a COVID-19 Response Supplier. Response suppliers are badged and placed in a special category on our website so companies and organizations that need your products and services can find you.
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