Cut 5 - 7 strips of fabric 1 1/2 inch wide each on the bias. You will need 2.5 to 3m of strips total. The bias is at a 45degree angle from the selvedge - see next image ...
The bias is the stretchy angle on the fabric. The stretch of the bias is needed to allow the piping to ease around the circle.
Align the strips right sides together as shown above, and stitch on the red line to make them into one continuous strip.
Trim the seams to 1/4 inch and cut off the excess points. Press the seams open.
Attach the zipper foot, with the needle a little in from far left (for a little wriggle room). Thread top and bottom with matching thread - tension normal. Place cord in the centre fold of the strip.
Straight stitch (length 2.5) down the length of the fold ensuring the piping cord is always to the left of the foot. Clip 2m of the finished piping.
Cut a 3inch diameter circle from the interfacing. Pin one end of the piping to begin the spiral on the NON glue side of the interfacing. Now move the needle position on your machine to the far left.
Start stitching as snug as possible against the piping, stop with the needle down and readjust when necessary. Align the piping as you sew around the spiral.
Continue stitching and clipping until the circle measures 3 1/2 inches in diameter (you will sew over the edge of the interfacing). NB: do not clip the piping seam on the last turn around.
Cut off the excess clipped seam underneath. DO NOT cut the last piping seam circle (as shown).
Use the pinking shears to cut the outer seam edge.
Cut the felt circle with a 4 inch diameter. The circle rotary cutter makes this easy - set the radius to 2inch, insert the pin into the felt and carefully turn the cutter to perfectly cut the circle.
Press the coaster to the felt to adhere them together. This is best done from the felt side as the heat will not go through the thickness of the piping.
Finish the outer edge with metallic thread stitching, _ _ _/\_ _ _/\ _ _ _ (length 1.5, width 3). Thread with a metallic thread and needle, and lower the top tension to 2. Stitch close to the piping.
Make a nice cool drink and enjoy ... or make a few more for family and guests. Idea: make them in different fabrics so every one knows which glass belongs to them.
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