u/John628556

I was recently surprised by the lack of waterproofness of some silpoly that I was working with. It's 1.1-oz. silpoly from Ripstop by the Roll. It's advertised as having a hydrostatic head of "~2000mm," but in my experience, it failed at far less than 2000mm.

Of course, there is variation in fabric. Some batches of a material that's advertised as having an HH of around 2000 mm will instead have a lower HH. But in my experience, the HH was dramatically lower.

I decided to run a second test, and you can see pictures and videos at https://imgur.com/a/x9RNDIz. The test is simple: take an unused, unfolded scrap of silpoly, fasten it to the top of a glass jar, pour water on it, and see whether any water leaks through to the bottom of the jar. This isn't a formal test of hydrostatic head, but it seems informative.

Within 30 seconds of pouring water on the silpoly, I got substantial leakage. The depth of water on top of the silpoly was never greater than 2 inches ≈ 51 mm. And 51 mm is about 2.5% of the advertised average hydrostatic head. This seems to me like a catastrophic failure.

But I am a novice. Am I just misunderstanding hydrostatic head or testing waterproofness in an illegitimate way? Alternatively, if my fabric really isn't up to spec, is it very anomalous, or have you had problems like this, too?

Copying others who've written on closely related matters: u/Big-Strain1830, u/orangecatpacks, u/Beer_Is_So_Awesome, u/KCBaker85, u/Accurate-Peace-954, u/FuguSandwich, u/dandurston.

I'm using 1.1-oz. silpoly to make waterproof "bread bag" sock liners that one can wear in camp. The idea is simple: when your shoes are wet at the end of the day, wear a dry sock, put a silpoly liner over the sock, and then stick your socked and lined foot into your wet shoe. A year ago, u/BeggarEngineering wrote about his similar effort.

These liners can have a simple shape. Start with a rectangle of fabric (say, 40" × 10"). Then fold it in half to make it, say, 20" × 10". Then sew up the 20" sides, leaving an opening at the top. The only remaining step is to seal the seams so that moisture can't get in. This is where I'm having trouble.

Old posts by u/orangecatpacks taught me about the importance of seam construction to waterproofing, especially for horizontal seams. In turn, I sew rolled hems on the sides of these simple liners. Then, to seal the seams, I use Seam Grip + SIL. I seal the inside and the outside of each liner, allowing 48 hours for curing.

But they still leak—a lot. The fabric itself seems waterproof, and the seams are mostly OK. The problem seems to lie with the corners at the bottom of each liner. I test waterproofness by submerging the liners in a pan that has a little water in it. I find that water always gets in, almost instantly.

What am I doing wrong? I think that I'm smearing enough silpoly into the seams, with enough force. So I suspect that the problem lies with my seam construction and especially with my corners. But I am very much a novice and could be missing something big.

[effacé]

[SOLD]

I am selling a 2025 Outdoor Research Astroman Air Men's Sun Hoodie in size L. It has long sleeves and the "pebble" color, and weighs 166 g = 5.9 oz. It also has a chest zipper that helps when you want extra ventilation.

This hoodie is in like-new condition. That is, it has no marks, stains, tears, or other blemishes.

It retails on Amazon for $105. I bought it new. I'm selling it for $65, which is almost 40% lower than the Amazon price. And my price includes shipping within the continental USA.

I wore this hoodie on two days and one night. I liked it, but I concluded that I prefer a different hoodie. That said, this hoodie is excellent for ventilation, for smell management, and for dealing with a lot of bug pressure. Outdoor Research advertises the hoodie as having "UPF 30-50+ sun protection."

Photos and a verification picture are at https://imgur.com/a/6Ccm6oh.

Payment and returns. I'll default to using PayPal's "goods and services" service, which can help with dispute resolution. I'll pay the 3% transaction fee. If you want to return the hoodie for a refund, you'll need to pay the cost of return shipping, and I'll need to get it back in excellent condition.