Intercolored plain grain

"Plain intercolored grain" likely refers to a fabric that has a simple weave structure (plain weave or similar) and is interwoven with threads of different colors or shades to create a striped or patterned effect.
In a plain weave, the warp and weft threads are interlaced in a simple over-under pattern. By using threads of different colors or shades, a striped or patterned effect can be created in the fabric. This type of fabric is commonly used in clothing, upholstery, and other applications where a simple yet visually interesting fabric is desired.