Why use a bouldering mat?
Bouldering mats, also known as crash pads, offer protection when climbing with groundfall potential. They use foam, or a combination of foams, to resist some of the force of a falling body landing on them, helping to reduce the likelihood of injury, erosion and fear.
Amazingly despite their simplicity, the bouldering mat (as we know it today) is one of the most recent climbing technology developments. The Sketch Pad was born in 1992, well after nylon ropes, sticky rubber and even micro cams. Perhaps unsurprisingly the overall design has not changed much since then, but the materials and details certainly have.
How do they work?
The ability of a mat to resist force comes down to the foam inside it and where that foam is. Bouldering mats use two types of foam:
Dense closed cell foam to distribute force over as much open cell foam as possible, which contains millions of sealed bubbles of air (think traditional camping roll mat).
Soft open cell foam to absorb impact, which contains millions of connected pockets of air (think washing-up sponges).
Manufacturers do not usually publish the technical specs of foam, remember not all foam is created equal, however thickness is almost always given. In theory the more foam the merrier, but in practice size and weight become issues; the largest mats now weigh almost 10 kg.
The configuration of foam in the mat can change the way it feels dramatically. Most mats now have one layer of closed cell foam on top (2 - 2.5 cm) and one layer of open cell foam of beneath (5 - 8 cm). Some mats, like the DMM Highball, use a second layer of closed cell foam on the bottom to give spread the force applied more evenly over rocky ground.
Which folding style?
Bouldering mats are an awkward size and shape for storage so folding them is essential. Some have a hinge down the middle which makes for very easy, neat storage, but does mean that you are missing some foam coverage in the ‘gutter’ that is formed in the middle on uneven terrain. On some folding models this effect is reduced by having a continuous layer of closed cell foam on top and only cutting the open cell foam beneath in half.
Others are made from large single pieces of foam, which are simply bent in half ‘taco’ style. These offer better protection, but take up more space when folded than their hinged cousins. Extended storage in the ‘taco’ position compresses the foam reducing its lifespan and can leave your mat permanently U shaped and no longer able to lie flat.
How long will my mat last?
Foam quality does place a large part on the longevity. All foam will degrade with use, slowly becoming softer and softer until your mat offers next to no protection. As this happens almost imperceptibly slowly it is good to start with a very stiff feeling mat.
Most mats are made from very strong fabrics these days, a common choice is 1000 dernier Cordura. Densely woven synthetic fabrics are extremely abrasion resistant and even water-resistant, the downside of this being that you will need something else to remove moisture and dirt from your shoes.
Most manufacturers have a few little features to distinguish their models from others. Here are a few of them and why you might consider them an advantage.
Most manufacturers now provide aluminium alloy buckles which are almost impossible to break, unlike those made of plastic. It is important to make sure that they cannot be landed on.
No mats are fully waterproof. Moisture in the air (and in your basement) can get into the open cell foam and cause mildew to grow, reducing its lifespan. Some mats come with the foam wrapped in plastic inside the cover.
Most mats can be carried vertically with rucksack style shoulder straps, some can be reconfigured to be carried horizontally with a single long shoulder strap. Waist straps make carrying large pads much more pleasant.
Many people do not use a separate bag when bouldering, preferring to stuff their gear in between the folded sides of their mat. Flaps which extend around the bottom and sides of the mat will stop it falling out.
Clean side up
The bottom of a mat inevitably gets dirty and muddy, which is why they are almost always black. Some mats fold so the side you land on (hopefully clean), is the one pressed against your back when carrying it.
90° corners make squeezing mats into cars difficult, are an obvious wear point and offer little protection in themselves.
Some mats feature a hinge which is cut close to 45°. Almost giving the best of both hinged and taco folding styles.
Being able to hang extra gear, a bag, or a second mat on a mat is very useful. As is being able to tether your mat to the ground with tent pegs in windy conditions, especially in Britain.