Clamshell Patchwork

Clamshells are created when half-circle shapes are connected and layered in an offset grid. I am fond of this shape and have used it as a quilting motif, an appliquéd border, and even as a decorative edge finish.

But I have never used it to create patchwork – until now. After all the fun I’ve been having making hexies using precut iron-on interfacing and my Apliquick tools, I wanted to try playing with some of the other shapes commonly constructed with English Paper Piecing.

Two-inch wide clamshell templates are available precut from fusible paper made with a 50%-soluble natural fiber. The papers do not need to be removed since they will semi-dissolve on washing and remain safely inside your project as soft fibers. Iron a clamshell template onto the wrong side of the fabric.

Cut out the clamshell shape from the fabric leaving an approximate 1/4-inch seam allowance.

Apply water-soluble glue to the seam allowance along the outside curve…

… then turn the seam allowance over the edge of the interfacing using the Apliquick rods.

This method makes it very quick and easy to prepare your clamshell shapes.

Two-inch clamshells fit perfectly on 2-1/2” strips of fabric, so for my first project I purchased a Hoffman “Bali Poppy” – 20 different fabrics laser-cut into 2-1/2″ strips – in the Sepia colorway. I decided to arrange the clamshells in alternating rows of light and dark and save the few mid-value fabrics for possible borders.

I also decided to sew the clamshells together by hand. Luckily, as a result of sharing this photo with a Facebook group of English Paper Piecing enthusiasts, I was warned about the challenge of keeping the clamshells properly aligned while sewing them together. It didn’t take long to understand why! So I devised a way to add a few markings to aid with the alignment.

A 2-1/2″ strip of light fabric was selected for the top base row and marked at 2-inch increments (the width of each clamshell). The quarter-inch seam allowance was marked for the placement of the top of each clamshell and the mid-point (1-1/4″) was marked for the placement of the edge of each clamshell.

If I had turned under the seam allowance around all the edges of the clamshell, it would be easy to see how the shapes fit together. But why turn under an edge that will end up getting covered? Instead, we just need to add a few marks to each clamshell to help with the placement.

From the back, insert a pin along the edge of the interfacing template at each edge and at the mid-point of the base. Turn the clamshell over to the right side and make a mark from the pin to the outer edge. You can also fold the clamshell in half to finger-press the mid-point of the curved edge.

For the first row, line up each clamshell with the markings on the 2-1/2″ strip of the top base row fabric. Pin and stitch in place.

Continue adding clamshells until the row is complete.

For subsequent rows, line up each clamshell with the markings on the preceding clamshells.

Continue adding clamshells until each row is complete.

For my next clamshell patchwork project, I’m going to go completely scrappy with Hoffman “Dot Pops” and try machine stitching. Stay tuned!


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