Field Notes

Lunch bag noir in two versions

October 04, 2015 | In Making

One of the ten makings challenges was to do one over, better. I made two iterations of a lunch bag.

Design Goal

Replace the plastic grocery bags I use for lunch with something as reliable but more attractive. It has to fit in my backpack, and must be spill proof to protect my laptop. It should be easy to clean.

Design 1

Lunchbag noir - design 1

The bag is roughly 6"x6"x10", large enough to hold a Tupperware snugly and have room for another little container and an apple.

The material is vinyl, with a 12" zipper along the top. JoAnne Fabric only had the gingham pattern in stock, c'est la vie. I added some black bias tape around the top to class it up and hide the seams.


The construction was similar to the storage box, a pocket with the corners folded under. I made a prototype with the same grocery bag I used for the storage box.

Here's a top-down view:
Lunchbag noir - inside

I sewed the corners down firmly to ensure nothing could get trapped in the pockets and transform into something undead. ( I still remember what happened to lunch bags in elementary school!) For best access with the sewing machine, I sewed the bottom first.

Next came the zipper across the top, and finally the side seam. My first zipper! Tricky, but not the swear-fest I'd expected. Zippers have a terrible reputation. I used a garment-style zipper, joined at the bottom, and it required some contortions to attach.

Road Test

The first version performed well. It holds containers in place nicely, and expands or folds up as needed.

How would it hold up in a spill? I filled it with water and discovered it leaks like a sprinkler. The vinyl felt like it closed up around the needle, but the holes were merely camouflaged by the print.

Design 2

Vinyl comes in 54" widths, so there was enough left over for a second bag.

The second iteration focused on minimizing seams along the bottom. It started with a 24" x 13" rectangle, folded and sewn along two edges:


This time I used a jacket style zipper, which separates into two pieces. I put the zipper on first, while it was unimpeded by other seams. It was much simpler to install.

Initially I thought to fold the corners up somehow, though it wasn't clear how to prevent food from getting trapped. While stalled on that question, I tested how the pocket held up against leaks. It wasn't perfect, but leaked much less than anticipated. I opted to trim the excess material at the corners and trade extra seams for crumb protection. The bottom seams look like an H.

Tent seam sealer solved most of the waterproofing problem. The smell fades quickly, but it's still best used outside. Here it is drying after a third application on a few holdout leaks along the bottom.



As a nerd I want to believe a plan will work if I think about it hard enough first. The realized models uncovered flaws and strengths that I hadn't foreseen. More testimony for favoring several short iterations over one grand attempt.

Two lunch bags are plenty. The next iteration will be a laptop accessory bag for all my cables and adapters. Pencil cases have a good design but fall apart. I can rebuild it. I have the technology. Better... stronger...

Most vinyl fabrics are made for rugged home-dec uses like tablecloths, and it shows. Enter the laminates. Laminate fabrics are regular fabric with a coating. You can make your own from any tasteful lightweight fabric and iron-on vinyl.