When you are working on high-voltage lines or dealing with live electrical panels, your rubber insulating gloves are the only thing standing between you and a lethal shock. Most utilities and industrial electricians are good about sending their gloves out for the mandatory dielectric testing every six months. But what happens between those tests is where the real danger lies. A glove can pass a laboratory test in March, develop a microscopic pinhole in April, and fail catastrophically in May if the worker doesn't know what to look for.
You cannot simply pull a rubber insulating glove out of its bag, put it on, and trust it. You must perform a visual inspection and an air test every single time you use them. The visual part is straightforward: stretch the glove and look for tiny cuts, embedded metal shavings, or ozone cracking (which looks like tiny, fine lines in the rubber, similar to cracked paint). But a pinhole can be invisible to the naked eye.
This is where the rolling air test comes in. You grab the open end of the glove, hold your wrist tight against the cuff to seal it, and begin twisting the glove from the cuff downward, trapping air inside. You roll it all the way down to the fingertips, squeezing the trapped air into the fingers. Once it is tightly rolled up, you hold it to your ear or bend the fingers to see if you feel or hear any air leaking out. If there is a microscopic hole anywhere in the rubber, the pressure will force air out of that hole, making a faint hissing sound or causing the roll to slowly deflate.
You have to pay special attention to the fingertips and the webbing between the fingers, as this is where the rubber stretches the thinnest and where pinholes usually develop from grabbing sharp wire or resting your hands on rough surfaces. If the glove holds air perfectly, you are good to go. If it leaks even slightly, that glove is dead. It cannot be patched, it cannot be taped, and it cannot be used as an inner liner. It must be destroyed right then and there by cutting the fingers off so nobody else accidentally picks it up out of a truck and trusts it with their life. It takes an extra thirty seconds, but it is the only reliable way to know your armor isn't compromised.
