Boar Hair vs Nylon Climbing Brushes: Which Should You Use?

Pick the wrong brush and you can polish a hold, leave chalk haze on a project, or shed plastic at the boulder. Pick the right one and you'll clean better, climb cleaner, and treat the rock right. Here's how to choose between boar hair and nylon climbing brushes — the two main bristle materials — for indoor sessions and outdoor sends.

 

The quick answer: for outdoor climbing on softer rock like sandstone or limestone, use boar hair. For gym holds and very hard rock like granite, nylon works fine. If you only buy one brush and climb both indoors and outdoors, boar hair is the safer default.

 

Why boar hair works for outdoor

 

Boar hair is a natural bristle that strikes a balance between stiff and soft. Dense enough to scrub chalk and rubber off a hold, but flexible enough not to polish the rock itself. It softens slightly when damp, which is helpful on dewy holds, and it absorbs oils and moisture — the two things that make grips feel slick. When the bristles eventually wear and shed, they biodegrade rather than accumulating as microplastic at the crag.

 

The trade-off: boar hair wears faster than nylon and can flatten under aggressive scrubbing. Plan to replace your brush every season or two of regular use.

 

Why nylon works for the gym

 

Nylon bristles are stiffer than boar hair and don't soften when wet. That makes them effective on gym holds (made of polyurethane, which doesn't polish) and on hard rock like granite. They cut through caked-on chalk faster than boar hair, last longer under heavy use, and are fully vegan if that matters to you.

 

The trade-off: on sandstone, soft limestone, and some gritstone, repeated nylon scrubbing wears the texture off holds in a way that becomes visible over time. Nylon bristles also shed microplastics that don't biodegrade — a real environmental concern as climbing areas accumulate decades of brush use.

 

When to reach for which

 

Use boar hair when you're climbing outdoors on sandstone or soft limestone (most U.S. bouldering areas), working a project where you don't want to alter hold texture, or carrying one brush for a mixed indoor/outdoor season.

 

Use nylon when you're brushing exclusively at the gym, climbing on very hard rock like granite or alpine quartzite, or you want a fully animal-free kit and you're not climbing on soft rock.

 

How to brush well

 

A few habits that help the rock and your sends:

 

Brush dry. Wet holds get glossier after a hard scrub, not cleaner. If a hold is wet, leave it alone and come back.

 

Brush gently first. Most chalk and rubber comes off with light passes. Save aggressive scrubbing for stubborn rubber smears.

 

Brush down, not in circles. Circular motion grinds debris back into the hold's micro-features.

 

Rinse your brush monthly. A quick cool-water rinse (no soap) brings stiffness back to boar hair.

 

A note on the environment

 

Brushing is one of the few climbing practices with a measurable environmental footprint. Boar hair shed at the crag biodegrades within a season; nylon doesn't. If you climb outdoors regularly, that's the strongest argument for boar hair.

 

Our brushes

 

At Footless Bird we make both. Our boar hair climbing brushes are the default — climber-shaped handle, dense natural bristles, six colors so you can pick yours out of the chalk bucket. Our vegan nylon line uses the same handle with dense plastic-strong bristles for fully animal-free use and harder rock.

 

Whichever you choose: use it gently, replace it before the bristles get sloppy, and pack out anything you find at the wall.