DIYSustainabilityTechnology

Dyneema fabric testing – reusable shopping bags

Living in NYC gives me a great appreciation for all things light weight, minimal, and compact. The best way to get around the city is the subway, which means not only carrying everything with you to and from the subway, but then up and down many stairs and then on foot to your destination.

Likewise, when I started rock climbing at the Gunks, the best way to get the most climbing in each weekend was to camp as it was a 2-3 hour drive from Manhattan.   For me, living in Brooklyn at the time meant carrying all my climbing and camping gear to the subway, transferring twice, then walking a half mile to where my friends car was parked. Definitely tedious every single week with so much weight to carry to and from. Eventually I switched from a tent to a hammock to start reducing weight, but still looking for ways to reduce weight.

Finally, when I started getting more serious about skiing, I had a similar problem trying to get all my gear to the office on Fridays again via the subway, then racing to Grand Central to catch the train to CT to catch a ride north. This was the ultimate wake up call;   all of my gear weighed way too much, so any new gear purchases had to fit a new light weight and extremely packable criteria.

From all of these experiences, I started brainstorming on lightweight, durable and packable — something I desperately needed. I learned how great dyneema was through rock climbing by using my favorite slings I then started hearing about Cuben fiber fabrics which later became re-branded as Dyneema Composite fabric (DCF) around this time as well. I saw some companies making Dyneema stuff sacks, tents, and tarps which look great but at that price I figured it would be better to experiment making the gear myself to learn about limitations. 

Dyneema fabric sounded like this unicorn of light weight and supremely strong which should also mean durable, right?  To see what was possible, I had to make my own gear and do my own sewing tests.  Once I found the online sources I ordered a few yards with plans to make stuff sacks and minimal backpacks….but NY state then decided to ban plastic bags so re-usable shoppers became the ultimate testing ground for these fabrics. I have not been gentle with these over the last 6 months and they show some wear but they are still holding on strong and I plan to continue to overload them and give them repairs and updates as needed.

A few things I found interesting these are;
-The Dyneema fibers are extremely strong but the laminated film is weak. The lighter weight fabrics are holding on with just the Dyneema fibers at the seams even though the film has been punctured by the sewing needle then stressed and stretched as the bag was used to carry too many heavy items.  I think this could be reduced by applying Dyneema adhesive seam tape to the seam area before and or after sewing the seam or creating welded or glued seams which would completely remove the needle puncture problem.
-The fabric is extremely light weight but it’s by no means bulletproof.  It can get punctured by bumping into a sharp corner (or a piece of NYC sidewalk scaffolding).  Luckily there is adhesive Dyneema laminated fabric patches that are easily applied to the damaged area.
-I don’t recommend using the Dyneema fabric by itself for handles because it will bunch up and compact into a very small and narrow piece making the bag handle uncomfortable to carry anything of decent weight.
-Initially the fabric is very flat and transparent, and also stiff so it holds it’s shape very well.  When new, these totes would stand upright with no help, but after months of use they don’t stand up as much or at all.  Also the fabric has become less transparent and more opaque and is only a little less noisy then when it was first made.
1.0 oz/sq yd Dyneema® Composite Fabric – Black CT2K.18
-Originally the handles were 1″ clean finished pieces of Dyneema but they became too uncomfortable as the fabric compacted itself to a very narrow strip. I added the white webbing on top of the straps to make the straps more comfortable.  Overall this 1.0 oz has been extremely durable, and the damage where the strap connects to the bag is because I sewed too many stitches in the area and it was not reinforced at this high stress attachment point.  It would have been better if the straps went to the bottom of the bag which would spread the load better.

 

0.8 oz Dyneema Composite Fabric CT2E.08  Gray
-I tried this cinch top so it could be carried on the shoulder then tied at the top to keep the contents inside.  The cord is 2mm Paraloc Stingray Dyneema single braid rope that is soft, pliable, has a good hand, knots hold well and unties with relative ease.  The thinness of the cord makes carrying heavy items more uncomfortable than a webbing would be.  I think this helps to keep from overloading the bag by being uncomfortable the heavier it gets, which could make the bag last longer.
0.51 oz Dyneema Composite Fabric CT1E.08  Gray
– I tried to attach the seams with double sided dyneema adhesive tape before sewing to reinforce the seams.  It succeeded in reducing the damage to the seam from sewing, but the amount of adhesive that was not encased in the seam became exposed as the bag was stretched and used.  This exposed adhesive then collected whatever dirt it could absorb leaving a dirty line around each seam.  This could be improved if the seams were sealed with adhesive seam tape after being sewn, which would also make the seams waterproof.
-Trying a different handle and closure system I used a 1.5mm accessory cord and a cord lock to cinch the top closed.  I wanted the handles to hold their shape so it was easy to grab the bag with one hand. I used this Paraloc Piranha with a Dyneema core and a poly braided sheath.  This cord is very stiff and holds its shape so I thought it would conform to the shape of the handle after it was sewn in place and the bag was weighted a few times, but sadly that was not the case.  Maybe I received the portion of the cord closest to the center of the roll because it is still very twisted and has not relaxed or changed it’s shape at all and the cord remains very curvy.
-Functionally I like this bag the best as it has separate closure and handles, is light weight and packable but the cord I used for the handles makes it look so sloppy.
0.34 oz Dyneema Composite Fabric CT0.3E.08  Gray
-The lightest bag not surprisingly has the most seam damage from sewing but it has like the rest been punching well above it’s weight class, carrying much more than it should be.  I would not hesitate to overload this bag with the only thing keeping me from breaking it is the cord is only 1/16″ so if it’s a heavy load it will be uncomfortable.  The cord is Amsteel Blue 12 strand single braid made of Dyneema SK-75 fiber and the 1/16″ tensile strength is 400lb.
-This is my favorite bag as it fits all my original criteria: lightweight, packable, durable.  I can go for a run with this in my pocket, grab some groceries on the way home and be good to go.  With this little bag there is never a reason to go anywhere without a bag with you, and makes a great addition to an EDC.  Like the other bags the issue to be solved is the lamination splitting at the seams from sewing which could be fixed with exterior seam tape.  I’ll make a few more options now that I have the correct tape that was out of stock last summer.