Natural fibers such hemp and jute are preferred for three reasons: softness (in comparison to a coarser fiber like manilla); tooth or the ability to hold a knot; lack of stretch under tension (in contrast to cotton) and less risk of rope burn (superficial and very nasty injury emerged by heat development if the rope is moved quickly over the skin). Jute has the additional benefit of being light.
Hemp, jute, linenEdit
Flexible, rough texture, high friction, low stretch, moderate durability, good strength.
Very popular with rope enthusiasts, these fibers have great grip and are very easy to tie with. Hemp is widely available and has a unique scent. Jute is smoother and lighter than hemp, and compresses more easily. Linen (flax) is the softest of this group.
Flexible, soft texture, moderate friction, moderate stretch, low durability, low to moderate strength.
Often marketed as clothesline, cotton rope can be found priced as low as 50' for $1, though higher quality cottons are stronger, more durable, and less stretchy. Its price, availability, and ease of tying make it great for beginners. Cotton is usually not recommended for suspension, with the exception of higher quality cotton with a rated breaking strength of at least 400 lbs or so.
Flexible, soft texture, moderate friction, low stretch, moderate durability, good strength.
These luxury ropes combine all the best characteristics of natural and synthetic fibers, but are considerably more expensive. Silk has good grip and is somewhat similar to cotton, while bamboo has less grip but also natural anti-bacterial properties and a shine like nylon.
Manila, sisal, coirEdit
Stiff, harsh texture, moderate friction, low stretch, moderate durability, moderate strength.
Seldom recommended for bondage since they're stiff and splinter easily, but they're very inexpensive and sometimes enjoyed by those looking for a very sadomasochistic experience from their rope. Higher quality coir (coconut) is the most usable of this group since it’s more flexible, but it’s also more stretchy and is not considered strong enough for suspension.
To get a rope that has the texture of a natural fiber, but is stronger, you might attempt mixing materials. Tested as working well so far is jute with rayon, nylon seems to stretch too much to be mixed with jute, topics of present research are jute-spectra and jute-dacron.