Basically, if you take the same lengths of soft and dense rope of the same size, the soft rope will weigh less.  With the same dimension, that means a lower density for the soft rope.

The benefit is the compressibility of the rope.  Soft rope will compress further for the same pressure than dense rope.  This can be useful for example on stove gasket applications.

With thumb pressure, soft rope has a compressibility of approximately 50% with moderate pressure.  Dense rope with the same pressure has an approximate 20% compressibility.

High Temperature, Heat & Flame Resistant Rope
Materials that resist catching fire, burn slowly, or retard burning can be described as either "incombustible", "non-flammable", "non-combustible", "fire-resistant" or "fire-retardant".  "Self-extinguishing" materials cease burning once the flame or heat source is removed.  "Fireproof" is understood to mean that an object cannot burn, but few materials are truly fireproof. 

Most of our products fall within one or more of the above descriptions: they resist high temperature, flame, fire, molten metal splash and weld splatter very well but may melt with prolonged exposures past their designed maximum continuous operating temperature.  They can also provide OSHA, ANSI-FM & NFPA compliance and personnel protection.

Using our products to retain heat or cold within pipes, hoses, enclosures or equipment helps conserve energy and resources, and reduces operating costs.
AB Technology Group: Keeping Our World Cooler
ä.  All products are non-asbestos and 100% asbestos free
graphite coated fiberglass rope soft
What is the difference between Soft Rope and Dense Rope?
high temperature and heat resistant fiberglass knitted soft rope