This is the last step. You will be sewing down straps, first the front panel and then the back panel, finishing each bag in turn.
I sew each strap down as a single, continuous stitch line, never removing the needle from the strap or cutting the thread until the bag strap is complete. This means I do some back and forthing but that has turned out to be both faster and sturdier than making two separate lines of stitching, one immediately inside the other. As part of the sewing process, I also zigzag over the raw, narrow, bottom edges of the bag straps twice, securing them from fraying.
The process is difficult and cumbersome to explain but not hard to do. All that stitching ensures those straps aren’t ever going to come loose.
Remember to keep the bag panels apart as you feed a bag through the sewing machine. It is endlessly annoying to discover you sewed the back panel down to the front along with the bag straps and then you have to rip out all that stitching.
Place the first bag, front panel up and slide the top of the left side strap under the presser foot. Start at the very top, left side of the bag strap where it lays on top of the fabric panel. Set your stitch to .4mm to secure the stitch line and then adjust to a longer length to suit the bag. Sew down the side of the strap, right alongside the edge, removing pins as you go.
The bottom of the strap determines what you do next.
If the bottom edge is a folded edge, pivot and sew alongside the edge with the usual straight stitch, pivot again at the other side and proceed up towards the top of the bag.
If the strap bottom is a raw edge, it will need to be enclosed in a zigzag stitch. Sew down to the bottom edge, and pivot. Reset the sewing machine to a wide, close zigzag stitch and slowly sew across the bottom edge, completely enclosing it within the stitching. When you reach the end, pivot and reset your machine to a straight stitch and proceed up the other side of the strap. As you work around the corners, you may need to adjust the placement of the bag under the sewing machine needle. A tiny skip won’t weaken the sewing.
After navigating the bottom edge, proceed up the side of the strap, heading towards the top of the bag. If you have a tag, it will be sewn in at this point. Pivot at the top and go across the top of the strap, securing it to the lip of the bag.
When you are back where you started, stitch back down towards the bottom edge, this time keeping your stitch line 1/8-inch inside the first line of stitching. Sew all the way to the bottom and then either enclose the raw edge in a second line of zigzag stitching or if the edge is a fold, sew a second line 1/8 above the first line.
Proceed back up to the top. Sew across the top of the bag strap just below the first line of stitching securing the strap to the bag lip. Secure the stitching with .4mm stitches, cut the bag free and you’re done.
Move on to the right hand side of the strap on the front panel and repeat the process.
Then flip the bag over and do the same thing to both legs of the bag strap on the back panel.
Put the finished bag on the stack, laying it flat with the gussets out and the bottom of the bag folded towards the inside, and move on to the next one. Laying the bags this way – they want to do it on their own – keeps them flat and wrinkle-free.
The other way to store a lot of bags is to lay them flat, in the same position, and then roll them up from gusset side to gusset side, letting the straps hang free. Store them in a box or in another bag. This also keeps them clean and wrinkle-free.
(This post is a draft from the upcoming book “Sewing Cloth Grocery Bags.” A complete list of the posts can be found here.)