The "plastic versus paper" debate doesn't just take place in supermarket lines. Anyone who installs drywall for a living has probably moved into either the paper tape or fiberglass tape camp. Seldom is there a middle ground.
No one can deny that fiberglass tape has uses far beyond covering up the joints in wallboard. Composed of twisted strands of fiberglass woven at right angles to one another, its resistance to high temperatures makes it ideal for wrapping electrical cable. It is also the tape of choice for the aficionados of homemade rockets, who use it to secure the centering rings to the main tube, and has evolved into a fixture in hospitals and doctors' offices, especially for use on casts and bandages.
Sold in a number of widths, this tape is generally easier to use than its paper counterpart. With the adhesive side down, its flexibility lends itself to molding to the shape of what it is covering or securing. It also has woven edges to prevent unraveling. Some fiberglass tape has been coated with various types of liquid polymers or plastics, and one American company has even devised a method of impregnating it with a form of rubber.
The tensile strength of fiberglass tape makes it tough enough for use on irrigation lines, pipelines and sewer lines. The advantage in that scenario is that it doesn't rot when exposed to constant moisture. The coated type is especially impervious to the elements.
Those drywall installers who prefer paper note that fiberglass tape tends to "wiggle" at some point after it is coated with "mud" to cover a joint, partly because its porous surface doesn't always provide a seamless connection. The result, in some cases, is a crack that becomes visible in that seam. On the other hand, many of these same contractors have high praise for the tape in conjunction with paper for repairs. The fiber glass is applied first, then more mud, then paper to form a firmer bond.