How do I store silk between seasons?

Wrap it in unbleached muslin, never in plastic. Plastic traps moisture and, in a humid month, that is how a fold becomes a stain.

Refold along different lines every three to four months. A crease that stays in the same place long enough stops being a crease and becomes a cut.

Keep a silica sachet in the fold through the monsoon, and keep the pile away from direct light.