by Casa de KissaBoth a shirt and apron (of this status) would have primarily been made of linen fabric and linen thread. Linen shirts were made white or natural colored, while aprons were almost always white, red, or black (Textiler Hausrat, 1990). The construction, as well as the pleatwork would have all been done with the same linen thread.
by Casa de KissaSmocking, known in period as pleatwork, was the Middle Ages answer to elastic. Not only is it decorative, it’s also a way to constrict lots of fabric into a smaller area, particularly the neckline and cuffs of shirt or gowns. It has been documented in art as early as the Lutrell Psalter made during the first half of the 14th century and was in use well thru the 18th and 19th centuries.