I've made tons of pillows in the past but for the living room of my new house I wanted to do some research to find the proper way to assemble and sew a pillow with a welted cord trim. Perhaps it was impatience but I didn't find much out there in the way of a good tutorial. Full disclosure: I probably only spent 5 minutes looking, but nonetheless I experienced a lack of good information on sewing welted pillows. What follows may not be most proper way to create a welted pillow, but it works for me and I am very pleased with the results. For you newbies to the home-dec world, a welt is a covered cord sewn into a seam as trimming.
First step is to cut your pillow fabric 1" larger than the dimension(s) of your pillow. I purchased 23" pillow forms so I cut 2 x 24" squares to make my pillow.
After cutting the main fabric for your pillow, you are faced with the most tedious portion of a welted pillow: the welt itself. Start by cutting bias strips of your welting fabric (I used a green contrast to the floral print of the pillow) at a 45 degree angle to the selvage. Desiring a fairly small welt, I selected a cotton cording for the welt that is 1/4" in diameter. To get approximately 1/2" of seam allowance on either side of the welt, I cut my bias strips 1 3/4" wide.
You might question the use of the bias strip here, thinking a pillow with straight edges doesn't need to waste all that fabric cutting strips on the bias. Let me save you a ton of time and frustration: DO NOT MAKE THE STRIPS OF WELTING ON THE STRAIGHT GRAIN! CUT STRIPS ON THE BIAS! Why am I yelling at you? Because I have made this mistake before!! The trim on the pillow ends up hideously misshapen and puckery. Its worth the extra effort to cut true bias.
After cutting more than enough bias stripping to surround you pillow, the next step is to sew the bias strips together. Take two bias strips and overlap them right sides together, with the long edges of one bias strip 90 degrees to the second bias strip.
Here are two examples of how you overlap the bias strips. Many of my bias strips aligned nicely like the example on the left, but sometimes the selvage edges are reversed like the example on the right, causing an inch or so extra waste that you must cut off later. Either way, it is important to sew a diagonal line from the point where the two strips cross at the upper left to the point where they cross at the bottom right. Make sense? Continue sewing bias strips together until they form a single very long strip.
Trim the edges 1/2" from the seam you just sewed as shown above and press the seams open (as below).
The next step is to make the welting. Grab the end of your cotton cord and align it with the end of the bias strip so the cord is on the WRONG side of the fabric. Fold the bias strip around the cord aligning both long edges of the bias strip. With a zipper foot, sew as close as you can to the cord within the bias strip. This step makes the welting much easier to work with when pinning it to the pillow.
Now that you have completed a length of welting that will go around the pillow, you may begin to place the welting around the outer edge of one of the pillow panels. Place the welting on the right side of the pillow panel so that the raw edges or welt and the raw edges of the pillow panel align and the rolled edge of the welt is towards the center of the pillow panel.
Though blurry, you will see how I start the welting in the center of one side of the pillow panel and pin toward the corner. At the corner I've gently rounded the bend and followed along the next side of the pillow panel. Pin all four sides in this manner. When you reach the starting point, overlap the two ends as shown below.
I suggest you pull out and trim some of the cording so that it isn't too bulky when you sew it, but this step is not critical.
Again with the zipper foot, sew around the pillow as close to the welt as possible. Sew straight across the overlap of the two ends of the welt without stopping.
Onto the zipper. Select an invisible zipper about the length of the bottom edge of the pillow. I've chosen a 22" zipper for my 23" pillow. It's OK if your zipper is larger, just cut it down and sew stay stitches so the zipper doesn't zip off the bottom. With the edge of one side of the zipper placed along the raw edge of the welt/pillow panel (the edge that has the overlap in the welt), pin the zipper through all layers as shown below.
Once it is pinned along the length of the zipper, open the zipper and sew the one side (still with zipper foot) to the welt/pillow panel edge so that the teeth of the zipper are as close as possible to the welt. Opening the zipper before sewing allows you to get closer to the welt. Do not sew the zipper around either corner curve of the pillow but rather keep the zipper entirely within the straight edge of the pillow.
Once the zipper is afixed to one pillow panel, place the second pillow panel (right sides together) on top of the first so that all edges/corners align. Carefully roll back the edge of the second pillow panel opposite the zipper
and pin the other side of the zipper tape to it after zipping the zipper closed to get the proper alignment of the two panels when the zipper is closed. Once pinned, open the zipper again and sew other side of the zipper to the pillow panel using a zipper foot. Stop short of the curve of the corner.
Zip the zipper so that it is 3" shy of being entirely closed. You need this space to open the zipper again for turning the pillow to the right side. Sew the two pillow panels together along the 3 non-zippered sides. You will also sew around the curves at either end of the zipper. Trim all four corners to approx. 1/2", removing excess fabric. Turn the pillow to the right side, stuff and fluff.
There you have it... a welted pillow with zipper!