This week I’m finishing up my desk seat, by adding a cushion. The seat can be used as part of a lounge chair, in combination with the rear-facing passenger seat, but it’s primary use is at the fold-down desk, that will be attached to the Murphy bed.
I chose a 4-inch, high-density foam core as a base, which has to be cut to size. To get it well-fitted inside its cover, I cut it about 1/2-inch longer in all directions.
Sizing the foam
An electric kitchen knife is a good alternative to a professional foam cutter, to cut the foam. Having neither, I fall back to an ordinary bread knife. While less effective, with some care, I managed to get both a straight and fairly clean cut. Using a medium-density foam would probably lead to less favorable results.
Before I start with sewing the cover for the box cushion, I prepare a cutting list; for that I use the fabric calculator at sailrite.com (i.e. for the ‘box corner cushion’).
I selected an interior/exterior fabric with UV protection. With an overwhelmingly white van interior and a white desk seat, I picked a bright red-colored fabric to contrast the white, while coordinating with the bright colors of the copied art work.
Like the foam, this fabric is slightly oversized, after I cut it to according to the required measurements. I continue by removing the four corner pieces according to the cut list, then fold over the fabric lengthwise to establish the center of the sides. There I notch out more fabric.
Before adding the zipper, I add a seam lengthwise on both sides; the fold is kept in place with the help of some basting tape until I sew the seam. One half of the zipper is sewn to each side.
More basting tape is used for additional seams and finally the corners are established, using 1/2-inch seams with 3-1/2-inch length (1/2-inch less than the thickness of the foam).
Where the zipper ends at a corner, a folded piece of fabric is sewn over the zipper to strengthen the seam. The zipper is then cut to length. With the exterior of the fabric folded out, the corners of the cover are fitted and the cover is ready to receive the foam padding.
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