Singer S900 Manuel D'instruction page 56

MULTI-STITCH ZIGZAG
This is a strong stitch because as its name implies, it makes
three short stitches where the normal zig-zag makes only one.
For this reason it is recommended for overcasting all types of
fabrics.
It is also ideal for bartacks, mending tears, patching, and
control.
SHELL STITCH
Turn under the raw edge and press. Place the fabric right
side up so that the zigzag part of the stitch sews just over the
folded edge, pulling the fabric in to form a shell hem. Trim
away excess fabric from the backside, close to the stitching
line.
SEWING ON A BUTTON
:Lower feed dogs
Position your fabric and button under the presser foot. Lower
presser foot. Turn the hand wheel to make sure needle clears
the button and sew over top of it as illustrated.
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