After crossing into the 50s, the body goes through major metabolic shifts that affect even our extremities. Keratin production—the fibrous protein that makes up the nail plate—slows down significantly. While a fingernail typically grows about 3.5 mm per month, that natural pace starts to decline by roughly 0.5% each year beginning around age 25. As a result, nails become thinner, develop vertical ridges, and tend to feel very soft. The immediate reaction for many is to trim them very short to avoid breakage, but it’s often during that very trimming that a harmful mistake is made.

Close-up of older hands showing vertical ridges on fingernailsPin
Nails often develop vertical ridges and thinness with age.

To see why this is problematic, it helps to look at the nail’s structure: it’s made of some 100 to 150 ultra-porous keratin layers stacked on top of one another. Surprisingly, the nail surface is nearly ten times more porous than facial skin and can take on up to 20% of its weight in water just from washing dishes or taking a shower. When it becomes saturated, the layers swell, separate, and the plate softens immediately. That moment—especially after age 50 when declining estrogen contributes to increased dryness and fragility—is when a metal nail clipper can do serious damage. The clipper’s jaws crush that already-weakened layered structure before finally cutting through it.

Nail technicians and manicure specialists all describe the same mechanical issue: metal clippers or standard cardboard emery boards tend to catch and tear apart the individual keratin layers. On a softened nail, that almost always leads to splitting. By contrast, a glass nail file, thanks to its ultra-fine abrasive surface, is uniquely capable of smoothing and literally sealing the nail’s free edge. The tip becomes more impermeable, which prevents water from seeping in and stops the edge from crumbling at the slightest everyday bump.

Metal nail clippers close to a fragile fingernail edgePin
Metal clippers can crush layered keratin and cause splitting.

Switching to this tool does require a slight change in technique to get the full benefit. The practical tip is to file nails once a week using a single-direction stroke—always from the outer edge toward the center—and avoiding vigorous back-and-forth sawing motions. Pairing this habit with a daily drop of castor oil gently massaged into the cuticles to nourish the nail base will help maintain results. Be prepared to be consistent and patient: at this stage of life, a nail takes about four to six months to grow out completely from the matrix to the fingertip, so lasting improvement won’t be instantaneous.