Lightweight Chameleons: The Julbo Density Review

Julbo Density Sunglasses

Julbo has been making sunglasses since 1888 with the guiding principle of innovation. Their innovation is no more evident than in the Julbo Density Sunglasses. Fantastic photochromic lenses with a wide field of view on glasses that weight less than a carabiner. In a world obsessed with lightweight functionality, what more could you ask for?


  • Frame Material: Rilsan
  • Lens: Reactiv 3-1 (75-17%) Light Amplifier
  • Color: Iridescent Blue  – Red
  • Weight: 20 grams
  • Country of Origin: Europe

The Julbo Density, a misnomer?

Let’s get the first thing straight, though these glasses are called the Julbo Density, they are anything but dense. They are the lightest sunglasses I have ever worn at a whopping 20 grams. That’s not a typo. I have personally measured these at 20 grams on my own scale. I often flip my sunglasses on top of my head when I do not need them and have genuinely forgotten they are there and spent time looking for them. 

The frame is made with Julbo’s Rilsan material. This is a polymer created from Castor beans made from castor plants grown on soil that is “low-quality.” This means the land the castor plants were grown on was not suitable for growing food, raising livestock, nor has not it been logged. 45% of the beans are crushed to make oil that is used in production of things such as Rilsan where the other 55% is used for fertilizer. For more on Rilsan, click here.

What are the Julbo Density?

The Density are Julbo’s lightweight minimalist sunglasses intended for both cycling and snowsports, specifically noted by Julbo is nordic skiing. I’ve taken them mountain biking, splitboarding, and hiking and so those are the applications I will concentrate on. The Density are available in a variety of lenses including Julbo’s awesome photochromic lenses called Reactiv, their non-photochromic sunglass lenses called Spectron and prescription lenses, called RxLab. We tested the Reactiv Category 3 to 1 lens. 

Rilsan. Lightweight and (a little too) Flexible

The frame is very flexible. In fact, I suspect my head is a little too big for these glasses. In hand, they have a great looking base curve but when I put them on, they flatten out a little, changing the look of the sunglasses and the effectiveness of their large lens. This is mostly not a problem until the sun is on my side and I find myself adjusting the glasses or my hat to compensate.  

This also means there is a little more wind flow passing the lens while snowboarding. It’s not a problem while skiing or cycling as you are more head on in these sports. I found the wind could bypass the lens a little bit more while snowboarding. 

So, if the glasses are that flexible they surely fall off. Nope, not a chance. I’ve gotten super sweaty in these (1,000m uphill in blazing 34 degree sun) and they stay right where I put them. The temples are adjustable with a great grippy and soft coating. The nose pad, though not adjustable, has inserts made of the same material.  There is no need to have a strap on these shades, they stay put no matter the activity. 

Nosepiece on the Julbo Density

What is a Reactiv Lens?

Reactiv logo on the top left. It cannot be seen when the glasses are worn

A large portion of Julbo sunglasses come with Spectron or Reactiv lenses. We tested the Reactiv 3-1 Light Amplifier lens. They are photochromic, changing from 17% to 75% VLT as the skies open and things become brighter.  The lenses change tint seamlessly and quickly and work so well it makes it hard to go back to glasses that aren’t photochromic. As you can see in the various photos the lenses change from having somewhat of a transparent blue when they are at 17% to a very reflective blend of orange and red when they are at 75%. 

They are non-temperature sensitive meaning the change does not get affected by ambient air temps. I did find on bright yet overcast days that the Reactiv Lens can default to a darker tint than I’d prefer, but this is a common issue amongst all photochromic lenses, not just Julbo. 

The lens is massive and sits on your face like a giant shiny windshield. It’s great. At the top of the lens is a vent that helps move airflow to the inside of the lens. I have yet to fog these lenses. 

Shows the jublo density sunglasses to scale
Curvy Boys


The Density glasses are another great addition to the Julbo line. As far as I’m concerned, their Reactiv lenses are the industry standard for Photochromic lenses. They are so light that the protective case they come with outweighs them by 42 grams. The soft case weighs 8 grams. There is no reason not to have sunglasses with you everyday, at this weight, you will not even know these are in your bag. If the sun pops, you’ll certainly know you don’t have sunglasses with you. 

In summer the Julbo Density worked really well. To be honest, I put these on first thing in the morning and didn’t take them off until dinner, all summer long. I’m sure I must have worn them to dinner a few times and forgot they were on top of my head. With a VLT range of 17 to 75% they can be worn safely from near dawn to almost dusk. 

In winter they worked fantastically on the ups. Bright but flat light could be a little challenging for the Reactiv lens as it tended to default to a fairly dark VLT reducing contrast. The flex of the frame would allow for some side light leakage in winter that was not a problem in the summer. There was also a little more wind passing my eyes than I’d like while snowboarding. I think this was due to my large cranium and sideways snowboard stance.

This is still a fantastic pair of shades that suits summer mountain pursuits, year round cycling and skiing that would match folks with medium or smaller heads.

shows person wearing julbo density sunglasses at the beach
Seaside Strolls in the Julbo Density

Who are the Julbo Density for?

The skier or cyclist looking to have the lightest sunglasses possible that change VLT just as fast as you can adventure. 

If you are interested in picking up a pair of Julbo Density, head on over to Julbo. For more Julbo reviews, hit our Search button.


BlackSheep Adventure sports was provided with a free pair of Julbo Density to review. This in no way affected our opinion nor the review.