Welting is that small, fabric-covered cord edging that you see on a lot of upholstery. It's used mainly as decoration but I think it probably does protect the seam from wear at least slightly.
Welting is one of my favorite things about upholstery, especially velvet welting which is like this cute fuzzy edge that feels nice to the skin. You can even make double or triple welting for a fancier look and feel, and it's not even that difficult.
When making welting for a project, you have to calculate how much you're going to need before ordering the fabric and use math to understand how that length translates to area. The way to cut the fabric is on the bias (slanted 45 degrees) because almost all fabric has more give when bias cut than when it's cut any other direction. This extra give allows the welting to curve around the corners instead of being stiff and difficult to work with.
So you cut all these bias strips, usually about 2" wide, and sew them all together into one large strip, and let the seams also be slanted.
Now it's time to put in the cord, which requires a zipper foot. Velvet is also really difficult to sew because it tends to "walk around" on the machine as the pile (fuzz) propels it in random directions, wherever it sees fit!
I also want to highlight some of Elizabeth's work:
Look at this cool moon mosaic featuring so many different types of materials: glass tiles, beads, turquoise chips, buttons, millifori cane, and even a faience scarab!
Next time I will continue this series on welting and show you how the "magic" happens (matching up two ends of welting.)
Best wishes!
--Pam