I'm sure I've seen how to do this on BPL but I'm not having much luck searching for it. Can someone refresh my memory?

Example: CT2K.08

The 'CT' is 'Cubic Tech'

The '2K' is the amount of spectra

The '.08' is the thickness of the mylar membranes on either side.

Sometimes you see additional letters in there like 'HB' which stands for 'High Bias' which means it has spectra layered at +/- 45 degrees in addition to the regular stands at 0 & 90 degrees.

CT2K.08 is the normal 0.74oz/yd stuff. The lighter cuben's being used use the same mylar layers but less spectra. 0.33oz is CT0.3K.08, 0.48oz cuben is CT0.6K.08, 0.51oz cuben is CT1K.08.

The heaver 1.5oz cuben used in some applications (ie. packs, some tent floors etc) is CT5K.18. Notice the membrane is over twice as thick. This was the lightest version of cuben that used the thicker membrane, but now there is a 1.2oz cuben out that uses the .18 membrane but less cuben...probably around 3K I'd guess. This seems like great stuff for groundsheets, tent floors etc where abrasion is the main concern.

Thanks Dan. I thought I was looking at them correctly and indeed I was. My mistake was assuming that CT had kept their line card up to date. Absent is a 1.2 oz/yd fabric with the thicker mylar membrane.

Too bad they don't offer a 0.18 membrane with the same amount of spectra as the CT0.3K0.8. That may be the ultimate tent floor material.

I wonder if you might just end up with a very expensive, but not much superior, version of a polycryo groundsheet. The UHMWPE fibers in the cuben might give it an edge in tensile strength but in toughness and abrasion resistance crosslinked polyolefin film outperforms boPET (Mylar).

I ripped a polycryo sheet completely in half when tugging on one edge of it. I thought I had nothing but my sleeping bag on it, but a full water bag was behind the sleeping bag. The polycryo let loose all at once. With fiber reinforcement, it might have torn an inch but not all the way, and not all at once.

I may not ever have a cuben ground cloth but I like ripstop grid imbedded in thin plastic films.

From fooling around with my yard of CT0.3K.08 there is a massive difference between the full fabric and the edge composed solely of the mylar films. That tiny bit of Dyneema makes all the difference in the world.