[fleetfoot]

I posted this over in the E90 forum, but thought I'd share here too since this sub-forum seems more active. This past weekend at Atlanta Motorsports Park, I finally got my E92 328i out on the track for the first time (saving the M2 for later). I wasn't sure what to wear, so I did a lot of research comparing clothing fibers, which I thought I'd share here. If you have additional insights from your experiences feel free to share!

TL;DR: If you don’t want to invest in a Nomex race suit yet, skip the 100% cotton clothing and wear Merino wool for a material that’s just as comfortable with much higher ignition temps, no melting, and WAY better cooling performance when you’re sweating, especially in the summer.

As an avid outdoorsman, I was appalled by the HPDE requirement to wear 100% cotton on the track (for fire safety reasons) since cotton is TERRIBLE for temperature and moisture regulation, particularly in the summer when many driving events are held. Cotton tends to capture moisture, which disrupts your body’s natural sweat cooling system. No wonder everyone always looks so sweaty out there! You can read more about why cotton is a terrible performance layer here: https://www.outsideonline.com/178508...end-base-layer

Wearing nylon or polyester sports garments near flames is a bad idea, since those materials will melt at relatively low temperatures, which can lead to dangerous skin injuries. Cotton helps you avoid the melting problem but totally compromises cooling performance and the resulting sweat can boil and cause steam burns. Nomex solves the melting problem, but it’s fairly expensive for casual drivers and I’m not sure how well it wicks…I’m guessing not great since many manufacturers don’t list “wicking” as a feature.

As I purchased a $99 Nomex balaclava that looked very similar to my $26 Merino wool balaclava that I use for snow-skiing, the thought crossed my mind: “I wonder how Merino wool would do in a fire?”. Turns out it’s WAY better than cotton! Check out these ignition temps:

• Cotton: 255 Celsius (no melting)
• Nomex: 370 Celsius (no melting)
• Rayon: 420 Celsius (no melting)
• Polyester: 485-560 Celsius (but melts at 252-292)
• Nylon: 485-575 Celsius (but melts at 160-260)
• Merino: 570-600 Celsius (no melting)

Wow, Merino looks pretty awesome with no risk of melting and a much higher ignition temperature than cotton or even Nomex! Additionally, Merino is self-extinguishing, has a low rate of heat release, and forms an insulating char when it does burn. Per Sola (a company that makes fire-resistant technical clothing): “Wool’s natural flame resistance properties make it an ideal fiber for protecting firemen, military and anyone else exposed to fire or explosives. Wool’s attribute of only smoldering and not melting or dripping into the skin, can be a lifesaver.” If merino is good enough for firefighters, I think it’s good enough for me to drive in!

Now for those of you thinking, “no way I’m wearing itchy long-sleeve wool shirts and pants in the middle of the summer” go ahead and throw out your preconceived notions of what a wool garment feels like. Merino wool is super comfortable, and per my favorite gear site Switchback Travel, it’s “just as good of a summertime material as it is winter. We consistently wear merino wool for running, hiking, and mountain biking for its comfort across a range of temperatures. In the morning, it’ll keep you reasonably insulated, but you’ll be cool, dry, and ventilated once you start working up a sweat.” You can read more about Merino’s performance characteristics here: https://www.switchbacktravel.com/mer...is-it-worth-it

So, if you’re just getting started on the track, I’d suggest checking out some Merino clothing to stay safe AND comfortable. You’ll also be able to wear these things in daily life or under a Nomex suit if you buy one in the future. Here’s the 100% Merino apparel I bought after quite a bit of research:

• Balaclava ($26): https://www.amazon.com/gp/product/B000R7F3MQ
• Shirt ($70): https://www.amazon.com/gp/product/B007J3KGCI
• Sweatpants ($100): https://www.amazon.com/gp/product/B0758L69M9
• Briefs ($27): https://www.amazon.com/gp/product/B075RHJQ6T

Total: $223

Comparable Nomex motorsports stuff:

• Balaclava ($85): https://store.windingroad.com/sparco...omex-balaclava
• Shirt ($199): https://store.windingroad.com/sparco...nderwear-shirt
• Pants ($87): https://store.windingroad.com/k1-rac...derwear-bottom
• Briefs ($115): https://store.windingroad.com/sparco...nderwear-boxer

Total: $486

Here are a few of the sources that support my hypothesis that Merino is probably the best material for you to be wearing in a fire (beyond a Nomex suit):

• https://www.solagear.com/2018/02/mer...born-in-nature
• https://iffmag.mdmpublishing.com/mer...the-challenge/
• https://futuretextilemachines.com/ne...fire-fighters/
• https://ufpro.com/us/blog/article/no...-reality-check

[detroitm2]

Interesting to see track day organizers requiring specific clothing material. For racing, obviously it's a requirement, never seen it required for regular HPDE/trackday events.

[Rumbloki]

Thanks, for putting this together!

[dvas]

Originally Posted by detroitm2

Interesting to see track day organizers requiring specific clothing material. For racing, obviously it's a requirement, never seen it required for regular HPDE/trackday events.

Ferrari club HPDEs requires nomex suits. Because Ferrari. Only club I've encountered this with.

BMWs don't seem to spontaneously combust so my race suit doesn't get all that much wear.

[richard in NC]

Is it because of this thread that I'm now getting Merino Wool ads on Facebook?

[Rumbloki]

Originally Posted by richard in NC

Is it because of this thread that I'm now getting Merino Wool ads on Facebook?

Yes.

[pruettfan]

Cotton is the worst of all material in this situation. So easy to ignite. I would rather have no sleeve than a cotton sleeve.

[Daytona_550]

This thread is genius! I mean, has anyone ever seen a merino sheep on fire? Anyone??

[greasypeanut]

Why is nomex used in suits if it seems merino wool has higher ignition point, doesn't melt, and firefighters use it?

[fleetfoot]

Originally Posted by greasypeanut

Why is nomex used in suits if it seems merino wool has higher ignition point, doesn't melt, and firefighters use it?

Great question. I spent some time trying to figure that out but couldn't find a good answer. There was one article about how the military is actually blending merino and nomex to create new base layers. So there must be some unique value in each material. Perhaps nomex has greater durability? Merino is pretty strong but you can tear it up if you wash it with other rough/catchy clothing. You also want to air dry it.

Anyone else know of an advantage nomex has over merino?

[Rumbloki]

Is one more breathable/cooler than the other?

[fleetfoot]

Originally Posted by Rumbloki

Is one more breathable/cooler than the other?

So I did a little more research. I can't find much comparing Nomex to Merino, but Nomex is a synthetic fabric comparable to Nylon so we can probably use Nylon as a good proxy.

Let's define a few terms:
-Breathability: The ability for air to move through a fabric.
-Wicking-ability: The fabric's ability to stay dry and move moisture (through capillary action) to its outer surface for evaporation.
-Durability: The fabric's ability to resist abrasion/damage.

To stay cool on a hot day, you want a fabric that breathes well so you can stay cool from convection. But then when you start sweating, the fabric needs to move that moisture away from your skin so it can evaporate on the fabric's outer surface, which has a cooling action when heat energy is used to convert the liquid to a gas. Wicking also helps you feel less clammy.

If your fabric doesn't breathe, you're going to build up body heat from lack of convection. If your fabric doesn't wick, your sweating cooling system is going to be ineffective.

I've never seen numeric ratings for these characteristics, but they're generally rated on a low/med/high scale. This is what I found:

Nomex: low breathability, high wicking, high durability
Merino: high breathability, medium wicking, medium durability
Cotton: high breathability, low wicking, high durability

From what I read, Merino is going to have better cooling capabilities on a hot day due to having both good breathability AND wicking. Even though Nomex has terrible breathability, it could be more popular in the motorsports world due to its higher durability, or maybe just good marketing by its creator, Dupont.

Sources:
https://www.rei.com/blog/hike/what-d...e-wicking-mean
https://www.rei.com/blog/run/how-to-...thable-fabrics
https://www.ejisinc.com/blogs/news/w...wicking-fabric
https://besthiking.net/comparison-of...yer-materials/

[Rumbloki]

Thanks, again. This is good stuff.

[fleetfoot]

Originally Posted by Rumbloki

Thanks, again. This is good stuff.

Sure thing! Hopefully this helps folks be safe AND comfortable for their next summer track day. I always drive better when I'm not overheating.