Bought some of the women's Champion all polyester windshirts at Costco for around 9 dollars plus some change and which weigh 6 oz. Problems: Probably no DWR, and too breathable. Guesstimate around 75 to 95 CFM–easily twice as much as our 2012 Houdini's.
Solution: Just in case there was some DWR, put them through some hot washes with strong detergents to get rid of any, then rinsed very well.
Took some 100% silicone *adhesive* (not caulk) and diluted a lot with paint thinner, took a hand held blender and mixed it **very well**. Applied with a foam brush to the outside of the fabric, while hot out of the dryer, and then wiped over with a smooth microfiber cloth to work it into the fibers more. Let them dry outside for awhile (till most of the paint thinner dissipated), then put them in the dryer on medium with a wrung out/wetted cotton wash cloth to speed up the curing of the silicone. Still will let them hang up in the closest for a couple of more days before any use.
CFM almost halved and closer to the ideal range, with a truly durable water repellent coating. Now, will just have to occasionally clean very well, and maybe once every couple of years or so, spray with some cheap silicone spray to refresh/add to the DWR a bit.
Also beefed up the Houdini's we have. Coated all the seams with same mix, applied some to crucial areas like the shoulders, top of upper arms, and top of the hood. Hoping it will work better with the Nikwax Analogy Pump Liner from Cioch that i have and the pseudo knock off one i got for my partner. Previously, i had experienced some noticeable water ingress near the shoulder areas with the above combo during testing. If you've ever seen a Houdini, you know that there are A LOT of seams at the shoulder and hood areas.
Anyways, the above is a cheap and effective way to get a truly durable/long lasting DWR on one's windshirts/jackets, provided they are breathable enough to begin with. If they are very tightly woven using ultra fine fibers, and the material itself isn't that breathable to begin with, you don't want to do this, will decrease breathability too much (and turn it almost into silnylon albeit probably slightly more breathable than same), but perfect for fabrics that are TOO breathable or quite breathable to begin with.
The general concept is loosely similar to that of EPIC fabric by Nextec, however, i have no idea if the means of application, specific chemicals, etc are similar. I'm convinced that EPIC or DIY silconized windjacket fabric is the perfect compliment to using a Paramo type pump liner. One of the issues reported about Paramo jackets/systems is that they become noticeably less effective as the DWR washes and abrades off, which can happen on a single trip with most DWR's if there is a lot of rain and you're out for awhile. Most DWR's have this problem to some degree or another, and rubbed in silicone seems to be the most durable of the DWR's so far.
