i decided to see if i could make my own sil nylon out of breathable 1.1.
i decide to soak it on, thinking i could get a much more consistent coating than with a brush, and also thinking i could make it alot thinner and it might soak in to the interior fibers better making it more like impregnated than coated, and that maybe it wouldn't wear off like a coating might.
i mixed mineral spirits and silicone to get something thin enough to soak the fabric in, soaked one, thinned further, soaked another, thinned again, soaked a third.
i gave all three the shower head test, the first one, the thickest mix (#1) seemed the best, it was also apparent that any excess should have been wiped off before it dried, seems like it will not drip off unless it's too thin.
the first test was done with 6" squares, so then i cut out an exact sq. yd, weighed it at 1.1/32g, i eyeballed a larger mix that looked like the first one, soaked, wrung out, and wiped both sides as dry as i could and let it dry over night.
results are good, weighs exactly 1.3/38g, and seems to do about as well or at least close to sil on the shower head test, i'm thinking if it would have been a tarp, i would have set it up tight, to fully stretch it, then wipe it down, this may allow mix to penetrate deeper and better into the inside of the fabric better, worked suprisingly well the way i did it though.
can't say about durability, did seem like i got most of the sil off the surface already though by wiping it down.
don't know when i'll make a whole tarp, i just wondered about it awhile ago, and i happened to have the silicone out yesterday, sorry i don't have any exact mix ratios, i couldn't find anything to measure with but my kitchen stuff, so i just eyeballed it all. it was runny, but still had a little thickness left, and was pretty cloudy looking at an inch deep, but pretty clear at a half inch or so.(as i remember it)
i know sil is hard to find in many colors, so this may be an option, especially if you want exact color matches.
don't know about tear strength, sil has a higher tear strength than breathable 1.9, so i don't know about this stuff.
i also don't know how factory impregnation is done or if this is similar or not, i just know impregnation is present on the interior of the fabric as this seems to be as well.
maybe somebody has already tried this and knows more about long term use.