Difference between 1/4 grid cloth, poly silk, sail

[Thomas Worth]

I know this has already been asked a few times, but I am interested specifically in the diffusion properties of each type of diffusion material: 1/4 grid cloth, poly silk, and sail. I'm mainly interested in diffusing direct sunlight, using a large butterfly / overhead. I'd like the softest light I can possibly get while losing only about a stop. The fabrics can all be found in 1.0 stop versions, so I'm guessing the real difference is how much diffusion / ambient light they produce. Any info on this would be much appreciated!

[Stuart Brereton]

If they are all the same density, I doubt there's much to choose between them in terms of diffusion. Silks have a tendency to have slightly specular hotspots when placed in front of lamps, but this effect would be minimal when diffusing the sun. Grid cloth 'crackles' in the wind, so you would want the 'silent' variety.