Green cotton means that the cotton is unprocessed and unwashed, no bleaches, no dyes, no chemicals or fungicides are used. It's completely RAW AND NATURAL.
Green cotton has a natural odor that will dissipate over time. It’s often described as earthy or musty. What you smell is not mildew or mold, it's cotton seed oil in the fabric. When cotton is harvested, some cotton seeds are broken, releasing the cotton seed oil scent into the cotton boll, just like what happens with the popcorn seeds pop. If you have ever been in a cotton field, this scent may be familiar to you. The intensity will vary depending on how recently the fabric was woven. Most of the time it has dissipated long before the material reaches the customer but occasionally it can be noticed by some. Since it's an oil base it may not initially wash out with mild detergents. It's not toxic or harmful, but it can be offensive to some people. If the smell bothers you, soak the bags in vinegar and baking soda overnight and then wash. Hanging them up to provide full air circulation is the easiest thing to do, if you can find a sunny location it will really accelerates the dissipation process.
If you look closely at our natural muslin and canvas bags bags you will see the tiny darker brown flecks within the fabric weave. These are natural leaf, stem and seed remnants of the cotton plant. When fabric is processed with bleach and dyes they disappear from view, but since these bags are made of unprocessed fabric they will appear in varying degrees.