Bamboo
Companies, such as Greenlight Surfboard Supply, manufacture a natural bamboo glassing cloth that shares several of the characteristics of fiberglass cloth -- except, of course, for its deleterious effects on the environment. Bamboo glassing cloth is made from one of the most durable and versatile renewable resources on the planet. It's flexible and strong, making it ideal for laminating surfboards and other watercraft. Bamboo glassing cloth is about $6 per foot.
Hemp
The hemp plant has gained something of a negative reputation for its association with cannabis, but it is actually a resilient plant that doesn't exhaust soil and has a variety of uses. The hemp plant helps remove carbon dioxide from the environment as it grows, which is more than can be said for fiberglass, which relies on toxic petrochemicals for treatment and processing. Hemp cloth is an environmentally-friendly alternative to fiberglass that is also cheap to make and use. 6.5 oz. hemp fabric from a retail outlet costs about $30 a yard, with heavier fabrics costing more, and wholesale bulk orders costing less.
Natural Grass
Like hemp, cloth can be woven from dried natural grass, making it a suitable alternative to fiberglass cloth that is also available in abundance. Natural grass can be sourced locally from saltwater habitats to ensure the resulting fiber is hardy and resistant to wear and tear. Look for manufacturers that use natural grass fibers in their ecofriendly surfboard and surfboard-related products instead of standard fiberglass. Natural grass cloths have a cost similar to bamboo cloths at around $6 per foot.
Basalt
Basalt fiber makes a mineral-based cloth composed of olivine, plagioclase and pyroxene. Basalt fiber is even more durable than fiberglass and also similar to carbon fiber, though it is much cheaper to manufacture than the latter. Unlike fiberglass, no chemicals or materials need to be added to basalt to make basalt fiber, which is sourced from carefully selected quarries, then washed and melted down. Basalt fabric costs as little as $2.50 per kilogram.