Silk based products are made by overlaying lace with a layer of silk. Silk has a more skin/scalp like appearance than lace because the weave is tighter than lace it does not have visible holes like lace and a mesh like appearance. Importantly, the construction of silk products, means that the silk hides the knots making knot bleaching unnecessary.
Silk cannot be flush with the lace so around the silk there is still a perimeter of lace (see photo below). This can be noticeable due the different textures of the two materials. Hiding the perimeter involves a degree of skill. This cannot be remedied by cutting the lace away as doing so can damage the seam causing the silk and lace to separate. This could ruin your item.
(cap of a full lace wig with a silk top)