Double Brussels stitch
Double Brussels stitch is a needlelace stitch, consisting of detached butthonhole stitches worked over a pre-existing outline. This is a more open filling stitch than single Brussels stitch, so the gap between the double buttonhole stitches should be made a little wider.
Double Brussels stitch is attached to the background of the fabric only at the edges. In the example below, a simple back stitch outline is used, but this could be a cordonnet when making a needlelace slip.
For more background see the entry for single Brussels stitch.
Outline the edge of the area which you want to fill with back stitch.
Work a double buttonhole stitch in the top left-hand corner of the shape, as for Single Brussels stitch.
Leave a gap between the two double buttonhole stitches and repeat along the row. Attach the stitch to the right-hand side of the shape by whipping the edge.
Whip the right-hand side edge again to bring the needle just below the first row.
Work another row of double buttonhole stitches from right to left, passing the needle through the loops of the previous row. Make sure to work two buttonhole stitches into the big loops of the row above (this will offset the second row).
Continue to the left-hand side edge of the shape, and pass the needle through the left-hand side edge.
Whip down the left-hand side edge to bring the needle just below the previous row.
Continue working rows of double buttonhole stitch back and forth across the shape in the same way until the shape is filled. On the final row, pass the needle through the loop above and the bottom outer edge as you form each buttonhole stitch.
Structure of stitch
Identifying Double Brussels stitch
A woven stitch using buttonhole stitch in rows to fill a shape. Two buttonhole stitches are worked into the loop of the stitch above on the previous row.
Various Authors, The Royal School of Needlework Book of Embroidery (2018) , p.277