Boardy

Produces a full, firm, and harsh feel often described as a boardy feel, in cloth filled with it.

Source: wiktionary

Gone, too, are the days of boardy, heavy clothes for hot-weather wear.

Source: wiktionary

Rice starch, on the other hand, penetrates better and gives a harder finish, with a fullness and firmness which is apt to be regarded as “boardy”; […]

Source: wiktionary

Rice starch gives clothes a boardy effect. It makes the fabric firm because it has good penetration into the cellulosic fibre.

Source: wiktionary