Blog — SoftShell


The Foam Shop in the Shadow of the Tesla Factory

In the shadow of Tesla’s Fremont factory sits an unassuming business who does specialty foam work for a wide variety of clients. When National Geographic needs a custom case designed to protect equipment from the elements, these are the folks they call.

Bob's Foam Factory

Sitting directly between San Jose and San Francisco, most of Fremont is a suburban bedroom community that serves both cities. But it actually covers quite a wide area and has many industrial sections as well.

When I first visited Bob’s Foam, I still remember the awe I felt when opening the door to the shop area, seeing solid blocks of foam the size of camper vans and saws large enough to cut them.

Minimal backpack foam producer Bob's Foam Factory

I told the guy in the shop who greeted me about my backpack project and the kind of foam I was looking for… something that would hold its shape, protect the contents, and be thin enough to be integrated into the liner itself.

He quickly grabbed a yellow legal pad from the small desk in the corner of the shop and started making diagrams. Despite the fact that I had been researching different types of foam for weeks online, I learned more about foam from him in 5 minutes.

I showed him my prototypes and got out my sketchbook to take notes. 

Minimal backpack foam producer Bob's Foam Factory

There are two general categories of foam- open cell and closed. Open cell is most common and cheaper because a lot of the material is taken up by air. It’s great for many uses like couches but it’s spongy and can break down over time.

In order to achieve the curved back of the Slim Pack, I would need something more rigid. An open cell foam dense enough to do this would be too thick. So he recommend closed cell.

Even within closed cell, there are tons of materials, densities, and even processes used to make it. He showed me some of the ones he stocked and they worked okay but ideally I wanted something a bit stiffer. “Well, there’s also crosslink but it’s way more expensive,” he remarked. 

If you’ve heard of crosslink, also commonly referred to as EVA, it’s likely in the context of shoes since this is the type of rubber used in high-end running soles. It provides excellent cushioning and doesn’t break down over time. It also doesn’t take on any water and can even float!

Outside of $100+ running shoes, EVA doesn’t have many uses which justify the cost so it wasn’t something they carried. But he said if I can find it, they could make the parts I needed for the bag.

As I prepared to leave, I thought he must be the owner since he was so knowledgable. “Are you Bob?” I asked. “No, I’m his son- Rob.” Funny, another second generation family business to add to my partner list along with my printer, die cutter, and shipping house.

My hunt for EVA initially didn’t go too well. I spoke to a specialty foam supplier who did a lot of work for Nasa and when I asked for crosslink she said- “Oh, you want the fancy stuff, huh? No we don’t carry that.” If this stuff was too fancy for Nasa things weren't looking too good!

As I expanded my search I ran across a terribly designed website that seemed promising. It’s funny- sometimes with industrial suppliers a bad website can be a good sign. It can be an indication that they have customers already and they often times have very knowledgable sales folks… which turned out to be the case.

Just a couple days after talking to the foam supplier, a sample box showed up. Opening it gave me a similar feeling of awe as walking into Bob’s Foam… in front of me was a library of foam, arranged by increasing density, much of it even available in different colors. With this arrangement I immediately identified the perfect one… and I could even get it in black.

When I talked to the sales person about the thicknesses available, it took me a moment to realize that he was saying I could get it in any thickness I wanted. But that was because I had to buy a whole block and they would slice or “scythe” it for me to order. They would drop ship it to Bob’s Foam and then they would die cut the parts for the backpack.

Pricing everything out, this would be one of the most expensive parts of the bag if I divided it out by how many we were going to make. I thought it was worth it but I would also essentially need to buy three times more than I needed.

Minimal backpack foam producer Bob's Foam Factory

It was pretty exciting to see my block of foam arrive at Bob’s. There was no way to know for sure whether the final cut parts would have the properties I wanted before we made our pieces, but it turned out to be even better than I expected. It slides right into the liner but maintains the shape. And since it’s closed cell you can also collapse it flat like in the bottom of a suitcase and then it’ll rebound to its normal shape. 

From educating me about the right foam to use to precision cutting the final parts, Bob’s did a fantastic job delivering this custom part that makes the Slim Pack possible. I’m glad to add them to my list of local manufacturing partners and look forward to working with them to bring more products to life.

Accidental Slim Pack Water Test

When I worked as a UI designer, there were several times when I had the opportunity to design for entirely new hardware devices. During the process, we would usually have prototype versions of the devices at various forms of completion. These could cost in the tens of thousands of dollars per unit and there were a handful of times when someone on the team would accidentally have one one fall off of their desk onto the ground. “Drop test!” everyone would exclaim in a half-joking, half-panicked tone. Everyone would be very happy if it passed.

Slim Pack Perfect Backpack Waterproof

Water Test of the Slim Pack Commuter Backpack

Well, a backer recently had the accidental opportunity to put our waterproof commuter backpackthe Slim Pack, through its paces during a flight. As he described:

"Just wanted to send a quick thanks/kudos for the Slim Pack. As it turned out, I received mine the day before we left for a week-long vacation in Mexico.

I had already planned to bring my laptop, so naturally took the opportunity to try out the new pack. Used it as my carry-on, with laptop and some other supplies. What happened next was great. As the slimpack was stowed under the seat in front of me, the air pressure from the plane popped open the person's water bottle sitting in that seat. She didn't notice as it slowly leaked almost a liter of water out beside the seat, directly onto the slimpack.

When I eventually reached for it, I discovered that both it and another bag I had under the seat there were drenched. Everything inside the other bag (nothing important fortunately) was also soaked. Slimpack contents though, including my laptop, were bone dry. (The exterior dried off quickly too.)" -Nathan

In my testing, I can control certain variables such as water intensity and exposure time… but in the field, conditions are more realistic. So far with rain and now this in-flight water torture test, it’s shown to hold up really well in real world scenarios.

Another backer shared his experience:

"Dave, I received my backpack in the very first batch sent. It is incredible. It was put through its paces this weekend at the NAMM show in Anaheim CA during our crazy weather. It handled the rain with no problem, and for those not in CA, this was an exceptional amount of rain. I carried my DSLR and my iPad in it with no fear. Truly impressed with the comfort." -Sam

We’re making great progress on the backorders and they’re coming out great… looking forward to getting them in the hands of the rest of the backers!


What goes in to a new color Soft Shell?

When I first introduced Soft Shell, the natural choice was to make black. It’s the most popular Tyvek model and, putting aside debates as to whether black is a color itself, it’s probably my favorite color- at least to wear.

I have to order a huge minimum amount to have it custom produced though and the whole lot needs to be dyed the same color. So that means I can have it made in whatever color I want, but I better hope enough other people like the color too! In order to introduce the initial lighter gray Soft Shell, I went through quite a learning curve about what it takes to create colors for custom materials. The Pantone system didn’t really work in the same way as I was familiar with for printing. And while there are Pantone systems for other materials, the way the actual product comes out will differ slightly depending on the exact material.

So what’s the safest most accurate method? Trial and error basically. To be a bit more technical, you could say it’s color matching and lab dips. What it boils down to is that if I can find something as close as possible to the color I’m looking for and send it to the manufacturer, they can try to formulate a dye to match it. For the first gray, I sent them a special edition Roger Federer jacket I had. 

For this time around, I found an earphone case that was exactly the hue I was aiming for, though I ideally wanted something of a slightly darker tone.

But it’s an imperfect process so a few big variables need to be controlled for...

The first major one is the material of the color I send them. Different types of fibers take dye differently and also reflect light differently so ideally, a color sample would have a similar appearance to the end material I want it to become in order to be accurate. But even if we were to examine two pieces of 100% cotton material, the weaves and thicknesses may vary. Technical fabrics are blends of all kinds of stuff so it’s very rare to find an exact match.

Second is context. A little swatch of a color is going to look different than a larger one… so ideally you can create a visual mock-up that’s somewhat similar in size. In this post about choosing a green to print the Tyvek wallets, you can see that I printed mock-ups with 1:1 scale and even included stitching lines.

Color mock-ups

I also mask out color samples with white paper so no other colors are visible. Even being near other colors or in a room with different color walls can have an effect. So when viewing any color, it’s important to do it in some kind of controlled environment.

Third is the lighting conditions. Similar to differences in how different computer monitors depict color, physical objects look drastically different with various lighting. One way is to use a full spectrum or daylight bulb. Most indoor lighting is too warm (yellow) to accurately show color. But what’s usually regarded as best is to use actual sunlight by going outside or right next to a window.

For this particular color matching process, the last element is the material of the sample that comes back. Since production of my actual material is complicated, the samples are of a similar material that’s slightly different. Therefore, I need to use just a bit of imagination as to how the thread density and fabric weight will affect things like folds in the material, which impact how the color is perceived.

When they send me the lab dip samples they usually will send two, sort of bracketing the target color. If they aren’t acceptable, they’ll go back and adjust things and send back two more. With the variability, it can be a bit nerve racking to approve the final one, but it’s really cool when the final product is produced and the color is how you imagined it. After all, in the end it’s about coming up with something that looks good rather than a technically perfect rendition of the reference color.

So what if you need thread that’s the same color as the material you just had produced? Don’t even get me started...

The new charcoal soft shell material has just been introduced as a color option for the Slim Pack Kickstarter project for both a backpack and wallet.

Charcoal Slim Pack

Soft Shell Charcoal Thin Wallets

What other colors of Soft Shell would you like to see?

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