From pattern:

Spun with low twist, alpaca produces a drapey fabric but is prone to stretching. When spun firmly, alpaca can lose the soft hand, but it wears wonderfully. Silk is lightweight, has great tensile, and can withstand a great deal of twist. Adding silk to alpaca lightens the yarn and keeps the high-twist yarn from stiffening, making the blended yarn stronger than the two fibers spun separately. The modular construction of this shawl makes it perfect for color-changing yarns.

notions:
split-ring stitch marker; tapestry needle.