Very easy to work with. This was for my first MYOG project and my first time using a sewing machine. Used it for my tent's doors and roof. Its very waterproof after I made my tent I tested the seam sealing spraying it with a garden hose and not a drop came inside.
Though this material is very waterproof, it rips extremely easily and then doesn't stop, so small holes turn into giant rips. I was planning on using it for a tent floor (as it is recommended on the FAQ, however I found the 1.1 SilPoly without coating to be much more durable) but decided to stop the project because not only would the floor rip, but the other material I ordered for the rain fly was the wrong color. With that being said, I will be able to find another use for these materials (though they are already cut) and I am confident that it's waterproofing will last. I would have given two stars but I think RSBTR is usually very reliable and helpful, even though this time I don't think their recommendation of this for a tent floor was good.
I love this stuff for tent floors. It feels more robust than the non PU4000 silpoly, but still super light.
I used the 1.1 oz Silpoly PU4000 to make a poncho with hood and sleeves modelled on a cheap but flimsy plastic one I bought in Vietnam.
The poncho seems to work OK but so far I have not used it in torrential rain. (I use it over my normal wet weather gear and pack to keep most of the rain off. Like a tent fly, it doesn't need to be 100% waterproof to work.)
Some things to note about the 1.1 oz Silpoly PU4000:
1. The weight is a bit hopeful. I measured it at 1.8 oz (62 g/m²) not 1.1 oz (37 g/m²). That is 66% more than advertised. Still, the poncho came out at 7.7 oz (220 g) about half a bought one but 4 times my flimsy Vietnamese one.
2. The website is a bit confusing about which side is which. The duller side should face the rain and the shinier side inwards.
3. It maybe "Ripstop by the Roll", but this fabric, despite having a ripstop pattern, rips very easily, especially along the roll direction. Handy for cutting (!) but it meant I could not use snap fasteners which I had originally intended. Make sure you reinforce any holes.
I used this fabric to make a tent. I used this for the roof and doors. I was easy to work with, lightweight, and very waterproof. I’m very satisfied.