Materials - Silk
Silk is produced by unraveling silkworm cocoons, after they have been heated in water to loosen the sticky sericin that holds the cocoon together. Equipment for this is known in Italy during the medieval period. The individual filaments would be plied together, with the fineness of the thread depending on how many were joined.
It seems there was no silk cloth weaving industry in England at this time though there may have been some tablet weaving of narrow wares there. Most silk was imported as cloth from Italy and points east, via Italy and other Mediterranean countries.
A number of Tabby woven silk cloths were uncovered in London, many of which were used for facings or linings. The ones used as facings were often un-dyed, and were a light brownish colour. Because these examples were cut into small pieces it is difficult to determine how wide the original cloth was. However, regulations on the weavers in Italy stipulate that taffeta, a tabby woven textile, was to be woven a specific number of "braccia" wide (resulting in 109-118 cm wide cloth). Many of the tabbies are reasonably well balanced with a warp and weft count between 30 and 40 per cm. Taffetas could be woven with warp and weft of a different colour, since silk was often dyed before it was woven.
There are a number of remnant pieces of silk brocades in the finds at London, but very little to tell us how wide they were, and only educated guesses to tell us were they came from. Certainly there was a booming business in silk brocades in Italy, many of which had elaborate and whimsical patterns and were sold around the continent and in England. Brocade and velvet fabrics are mentioned in the wardrobe accounts for Kind Edward III, though they mention few details about the cloth apart from the colour. I am working to find information on the weaving of these textiles in the 14th century. There is a mention of silk satin damasks that are used in a doublet of the 16th century that have loom widths between 55 and 58 cm- the width of the pattern element. Interestingly, this is roughly equivalent to one braccio. (T+C p125) Complex silk brocades are still woven in narrow widths (20-30" for Chinese 'dragon' silks), I would imagine because the complexity of the weave makes a wider loom impractical. I can only think that the same reasoning would hold in the medieval period.
Silk satin is known to us from the written records of England, but very few pieces were found in London. According to these records it was often embroidered and painted. The few that were found are warp faced (similar to most modern satins) but the ratio of warp to weft threads ranges from 1.5:1 to 2:1. This is a lower density than is customary nowadays, and it was therefore looser in texture than our modern satins.