Snowboard Design & Construction Part 4: The Base, Sidewall & Edges
This is the fourth and final episode in our snowboard design and construction series. We've covered the shape and profile in part one, wood cores in part two, and structural layers in part three. Last but certainly not least, it's time to focus on the base.
In this final instalment, we’re going to take a look at snowboard bases. We’ll go through the different grades of base material, look at how they’re manufactured and the difference in performance between the most commonly used materials. Once we’ve done bases, we’ll finish off with a quick look at the final elements of the board’s construction, namely the sidewalls and edges.
The first thing to look at is what a base actually does. This may sound like a pointless statement, but having an understanding of how the base allows the board to glide, will help you see why manufacturers use certain types of materials and why some give better glide than others. The best explanation of how the base works is to say that its main function is to improve the coefficient of friction with the snow.
What that really means in layman’s term is that it’s there to make it slide better. Before we take a look at the different types of base materials and how they differ in performance and durability, it’s worth dispelling a few myths about snowboard bases.
If you follow snowboarding closely, you’ll generally know that bases come in two styles, these are extruded and sintered. The general perceived wisdom is that extruded bases are cheap and offer poor performance whilst sintered bases are expensive and give better performance. However, the reality is somewhat more complex than that, because in some conditions and riding styles, extruded is actually better than sintered.
How snowboard bases are manufactured
It’s worth looking at the differences between the manufacturing processes of these two different materials as this will give you an insight into why there’s such a difference in performance between the two
The starting point for both types of base is UHMWPE plastic, which stands for ultra-high molecular weight polyethylene. This is a tough and durable thermoplastic that has a high resistance to abrasion and a very low coefficient of friction, making it perfect for use on things that slide.
In both base types, the raw material comes in granular form and goes on to one of two processes to be formed into a sheet material, depending on whether it’s going to become an extruded base or a sintered base.
Extrusion is the easiest process to explain as it’s a relatively simple manufacturing process. It starts with the raw plastic granules which are fed into a sealed vat. This is then heated up until the plastic granules melt and turn into a liquid. This molten plastic liquid is then forced through a flat die and a series of rollers to be formed into a sheet material. Once this sheet material has cooled, the upper surface is chemically treated to create a rough finish to enable resin to bond to the surface during the board construction. The bottom surface is left smooth, creating a low friction material that slides well across a wide variety of snow conditions and temperatures.
Extruded bases have always been pretty simple as there was just one type. However, over the past few years, we’ve seen extruded bases become available in different densities. These are formed in exactly the same way as a traditional extruded base, the only difference being, that the liquid plastic is put under pressure before being extruded. So, this means that when you open the dye, the pressure forces more liquid plastic through creating a denser base material.
The starting point of a sintered base is actually the same as an extruded base. You start with the UHMW-PE granules, but this time those granules are placed into a tubular mould. This is then heated gradually, and as the plastic granules start to soften, they are then compressed under high pressure, so they start to bond together. As the granules haven’t fully melted, it leaves air pockets which are similar to pores throughout the material. This is then left to cool down, creating a dense plastic billet. The billet is then removed from the mould and now resembles a large Swiss cheese. This is then placed on a machine which rotates the billet across a large blade. The blade then shaves off the sheet material which as per the extruded base is then treated on one side to create a sealed rough finish ready to bond to the board.
The beauty of manufacturing bases this way is that its possible to manipulate the density of the material allowing the designers to offer harder bases with improved wax holding. By using finer granules during the sintering process, you end up with a denser material with smaller pockets of air. This creates a harder and more durable base. However, because of that increased density, it’s also harder to wax as those air pockets are smaller. That means that you’ve got to work the wax in a lot more than you would with a regular sintered base. But once you’ve got that wax in there, it’s going to stay in a lot longer, so you’re not going to have to wax anywhere near as often.
These different base grades are generally categorised by numbers. So, a regular sintered base is usually classed as a 2000 grade, going up to around 9000 for the hardest grade. So, to give you an example of what this means, a 2000 grade base has a molecular mass of around 3.5million G/moles whereas a 4000 base has a molecular Mass of around 9.2million G/ moles.
Advantages of extruded bases
Advantages of sintered bases
→ Reduces the cost of the board
→ Allows designers to use higher quality materials for the internals
→ Melted plastic repair has the same properties as the original material
→ Faster in its natural state than most sintered bases in their natural state
→ More resistance to impacts and damage
→ Well-maintained sintered bases are faster than all extruded bases
Before we move to the next section, it’s worth mentioning why you wax your board and what that wax actually does.
When you wax your board you fill the pores with the liquid wax. Once it has cooled down, you’ll then scrape off the excess leaving the now solid wax in the pores of the base surface. This remaining wax creates a hydrophobic surface which repels water. By forcing the water trapped between the base and surface of the snow to bead, it's forced away from the surface of the base. This reduces friction and therefore gives you a faster glide.
Base additives can be added into the raw material during the sintering process and can add additional performance to the board.
The first addative we’ll look at is the simplest, and that’s wax. By adding this to the sintering process it fills the pores throughout the whole material increasing the hydrophobic properties of the original base material, improving glide in between services. You should still wax this type of board though, the impregnated wax just means it won’t become really slow like a traditional unwaxed sintered base would.
Next up we have graphite aka Electra. By adding a blend of carbon and graphite to the base material during the sintering process, you get a base that dissipates both heat and static electricity reducing water film that creates suction and drag. To be honest though, this type of base only really brings any advantage at high speed where you have increased friction that allows the base material to heat up.
Finally we have Galium. This is a relatively recent addition to base material and quite popular on Salomon boards. Galium bonds together with the wax particles to create a tougher and more durable gliding surface, meaning you shouldn’t have to wax your board as often.
Snowboard Edges & Sidewalls
The purpose of the metal edges on a board is to provide traction with the snow when turning the board. The sharp corner cuts into the snow and engages the board through the turn. It also adds protection to the side of the board.
Snowboard edges are measured in the Rockwell hardness scale. This is a test which is done by measuring the depth of identation of a large load to determine the hardness of the material. Snowboard edges usually come in between 41 and 52 for a regular board up to around 60 on higher end carving boards.
So, the question is, why wouldn’t you just use the hardest edge. It’s not quite that simple as hardness doesn’t always equate to strength. As you increase the hardness, the edge can become brittle. While this isn’t so much of an issue on something like a race board where you want maximum sharpness and you’re not really going to impact anything hard, on a jib board where that edge is going to be slamming into hard surfaces all the time it’s going to become a problem. That’s the reason you’ll see manufacturers using different edges on different types of board.
For a regular board you’ll usually be looking at between 46 and 50 Rockwells giving you the ideal balance between hardness and durability. Whereas for a jib board, you’ll generally be towards the lower end of the scale where the edge will deform on impacts rather than crack. You’ll generally notice this because the manufacturer will call out the edges with a snappy marketing term. Call it jib edges or anti crack edges or some other term.
Snowboard sidewalls always used to be a really simple topic. They basically just sealed the core and gave protection against impacts. However, as most things, they’ve just gotten more complex over the past few years. Instead of just protecting the core, they’re now also used as shock absorbers.
There’s a couple of ways brands use the sidewalls to dampen out vibration, the first of these is to change the type of material that is used in the sidewalls. Historically sidewalls were always manufactured out of ABS plastic. This material is strong and durable so great for adding that protection, however, because of its rigidity, it has very little ability to absorb vibration. So, over the past few years we’ve seen more and more brands start to introduce sidewalls constructed from either a combination of urethane and ABS or 100% urethane.
This unique material is available in different hardnesses measured in shores. However, it’s big advantage for sidewall construction, even for higher rated shores, is that not only is it strong and durable, it’s got great dampening properties. So not only do you get a sidewall that’s great at absorbing impacts, you get a sidewall that can also help absorb fatigue inducing vibrations.
The second way to use the sidewalls to dampen vibrations is to add layers of dampening material into to sidewall during it’s construction. This system is used quite hreavily by Salomon and involves adding a rubber layer into the structure of the sidewall. This helps absorb vibrations whilst still delivering that rigid feel that ABS gives you.
That’s our snowboard design and construction series finished, We’ve gone into a lot of detail but we're big belivers in if that info’s out there, there’s no harm in knowing about it. Watch the entire four-part series now on our YouTube Channel.