Fabric Expiriment

Posted by: 4evrplan

Fabric Expiriment - 01/24/13 11:13 AM

In another thread, I'd mentioned reading about people making their own tents out of LDPE with strategically placed "transparent duct tape" to carry the loads and that I was considering this method for making a backpack. Another member, far more experienced and no doubt wiser than me cautioned that the LDPE would stretch and pull away and tear at the edges of the tape. I'm sure this is true, however me being a newbie and not knowing my limits and being full of folly, I took this good advice as a challenge, and I set out to prove it could work.

[img]http://flic.kr/p/dPjjgL[/img]

The image above is of a 4.5" square of my test fabric. I started by cutting the shape out of a plastic trash bag. Then, I layed strips of the tape edge to edge at a 45 degree angle to my cuts until the whole thing was covered. Next, I put another layer of tape over the first, at a 90 degree angle to the first layer of tape (still 45 degrees from the edge of my patch). Finally, I trimmed the excess tape from the edges of the patch. The tape strips are 1" wide because I'd cut my 2" roll in half before I even planned on this expiriment, otherwise it'd be 2" strips. It's very tough, I can pull and tug on it all I want without deforming it. If I try to use my fingernails to tear it at the edge, it does deform a little, but it still doesn't tear. I had a friend in a post office weigh it for me and it came out to 0.02 ounces, so that means about 1.28 oz/yd.

(4.5/36) ^ 2 = 0.015625 square yards
1 / 0.015625 = 64 of these patches in one square yard
0.02 * 64 = 1.28 ounces per square yard <=EDIT: 0.02 is wrong! Should be 0.2, 12.8 oz/yd^2!

Since the scale only measures to the 100ths, I suspect it's not super accurate, but even if this patch weighed as much as 0.03 ounces, that comes out to 1.92 oz/yd, still very light.

One downside, is that the tape doesn't stick very well to itself; it has to be made this way so it comes off the roll. But, it sticks very well to the plastic trash bag, so if I did it over, I'd sandwich the plastic bag between the two layers of tape, and not only would it stick better, but it'd protect my fragile vapor barrier from the inside as well as the outside.

Another downside is that it sticks to dirt at the edges of the tape where the adhesive leaks out, so if you insist on super clean stuff, this is not the material for you.

Will it work long-term as pack building material? Only testing and time will tell.

EDIT: My math is wrong! This material is actually WAY heavier! It should have been 0.2 ounces for my test patch, not 0.02. This means it weighs over 12 oz/yd^2! I'm sure I would have caught my mistake earlier, but I haven't worked with silnylon, cuben, or any of the other traditional materials, so I have no reference for what it should feel like.
Posted by: topshot

Re: Fabric Expiriment - 01/24/13 11:45 AM

Good luck with that - the poor man's cuben fiber! smile

A few thoughts:
1. You won't be able to sew it worth a darn because it gums up the needle.
2. It will be very difficult to make a pack without sewing.
3. I doubt you'd be able to glue it like cuben.
4. Silnylon will be lighter IMHO. The little tape I used on my tarp added at least 2 ounces (~50% of the LDPE weight) as I recall.

However, I'd love you to prove me wrong so have at it!
Posted by: 4evrplan

Re: Fabric Expiriment - 01/24/13 12:12 PM

Originally Posted By topshot
1. You won't be able to sew it worth a darn because it gums up the needle.

I see two possible ways to deal with this. Either sew it by hand (no thanks!), or stop every few inches and clean your needle.

Originally Posted By topshot
2. It will be very difficult to make a pack without sewing.

Agreed!

Originally Posted By topshot
3. I doubt you'd be able to glue it like cuben.

I also agree with this, wholeheartedly!

Originally Posted By topshot
4. Silnylon will be lighter IMHO. The little tape I used on my tarp added at least 2 ounces (~50% of the LDPE weight) as I recall.

That's entirely possible, and may even be about the same price considering the amount of duct tape I'm using, but would it be as tough? I have no experience with silnylon.
Posted by: 4evrplan

Re: Fabric Expiriment - 01/24/13 12:17 PM

One other possible benefit, is that it may not need seam-sealing, as theoretically, the tape adhesive will seal any needle holes.
Posted by: topshot

Re: Fabric Expiriment - 01/24/13 01:44 PM

Originally Posted By 4evrplan
Originally Posted By topshot
1. You won't be able to sew it worth a darn because it gums up the needle.

I see two possible ways to deal with this. Either sew it by hand (no thanks!), or stop every few inches and clean your needle.

I stopped about every 12-18 but you won't get as far with double layers. Major PITB.
Originally Posted By 4evrplan
Originally Posted By topshot
4. Silnylon will be lighter IMHO. The little tape I used on my tarp added at least 2 ounces (~50% of the LDPE weight) as I recall.

That's entirely possible, and may even be about the same price considering the amount of duct tape I'm using, but would it be as tough? I have no experience with silnylon.
It will likely be as tough if not tougher than silnylon. However, it also won't sew as well as silnylon either since the "threads" in the tape are MUCH farther apart than normal fabric. I guess it works for cuben though, which also doesn't have a high thread density. It would have more "body" than sil though.
Posted by: 4evrplan

Re: Fabric Expiriment - 01/24/13 03:12 PM

In the interest of full disclosure, I should mention that the tape is Nashua brand instead of the Scotch brand. It's likely not the same weight as the Scotch, and I don't know how the weatherability or UV resistance compares, but it's plenty strong in this configuration.
Posted by: 4evrplan

It's much heavier! - 01/25/13 10:41 AM

My math is wrong! This material is actually WAY heavier! It should have been 0.2 ounces for my test patch, not 0.02. This means it weighs over 12 oz/yd^2! I'm sure I would have caught my mistake earlier, but I haven't worked with silnylon, cuben, or any of the other traditional materials, so I have no reference for what it should feel like.
Posted by: topshot

Re: It's much heavier! - 01/25/13 10:54 AM

Originally Posted By 4evrplan
My math is wrong! This material is actually WAY heavier!
I'm not surprised. smile I knew if I had put a double layer instead of single layers on just those places I used it that the weight of the whole tarp should have about doubled. Glad you found your error sooner rather than later!
Posted by: 4evrplan

I admit defeat - 01/25/13 12:01 PM

I'm admitting defeat with this one. Not only is it heavy, but the amount of tape needed means it's not even a significant savings over the cost of silnylon. I don't consider this little experiment a failure though, because now we know for sure.
Posted by: 4evrplan

Final Comments and Observations - 01/25/13 12:56 PM

A note on tape brands, Nashua vs. Scotch transparent duct tape: At first I couldn't find the Scotch brand transparent duct tape because it was actually branded as 3M, and I wasn't making the connection that Scotch is a 3M line of products. I now have a roll and I've been testing with it. The weights of the two tapes seem to be about the same, but the adhesive on the 3M is far stronger. The 3M's fibers are spaced out further, but I believe they're a bit stronger than the fibers in the Nashua, so the two tapes are about equally easy to tear. I have no idea how the overall strength compares, as I haven't done any load testing. The Nashua's biggest downfall is also it's best attribute; the less aggressive adhesive makes it much easier to work with.

Test fabric: I've come up with a much lighter configuration for my fabric, which is still plenty strong, although it's still much heavier than silnylon. It uses just over half the amount of tape as my first test patch, by only using tape on one side. To keep the strips from pulling away from each other, stretching the plastic between them, they are overlapped by about 1/8 to 1/4 inch at the edges. So far, this seems to work very well.
Posted by: billstephenson

Re: Final Comments and Observations - 01/25/13 02:56 PM

Did you ever look into the feed sack material?

It's pretty much exactly what you're trying to make, ie, it's a fiber reinforced plastic material.

It's lightweight, waterproof, durable, and you can sew it. Plus, it's proven to carry a 50lb load and if you have any friends with big dogs or horses you've got a source to get plenty of it for free.

Check it out next time you're at the grocery store, it's pretty impressive stuff for your intended use. It may not be lighter than silnylon, but it's easy to get and a whole lot cheaper!

Posted by: BZH

Re: Final Comments and Observations - 01/25/13 03:09 PM

Ikea bags are very similar too. I think you can find plans on the net for turning an Ikea bag into a backpacking bag.
Posted by: 4evrplan

Re: Final Comments and Observations - 01/25/13 04:01 PM

Originally Posted By billstephenson
Did you ever look into the feed sack material?

It's pretty much exactly what you're trying to make, ie, it's a fiber reinforced plastic material.

It's lightweight, waterproof, durable, and you can sew it. Plus, it's proven to carry a 50lb load and if you have any friends with big dogs or horses you've got a source to get plenty of it for free.

Check it out next time you're at the grocery store, it's pretty impressive stuff for your intended use. It may not be lighter than silnylon, but it's easy to get and a whole lot cheaper!



I've got a coworker with both dogs and horses, so I may be able to get a hold of some pretty easily.
Posted by: topshot

Re: Final Comments and Observations - 01/25/13 04:21 PM

Originally Posted By billstephenson
Did you ever look into the feed sack material?

It's lightweight, waterproof, durable, and you can sew it.
Hmmm. I wonder just how well it can be sewn with a normal machine? I know it comes sewn on the top but that's very heavy "thread" and only 3-4 stitches per inch. May have to try it someday since I've saved a few dog chow bags.
Posted by: billstephenson

Re: Final Comments and Observations - 01/25/13 07:47 PM

I sewed mine with a Singer 99 and nylon upholstery thread. That worked fine. I removed the cloth thread and resewed the bottom of the sack.

I sewed mine with the printed side out, and then turned the sack inside out so the white side was showing. For the top, I sewed nylon webbing with a standard buckle so it closes just like a dry sack. In essence, that's all I really made out of it, just a simple top loading pack.

Posted by: DJ2

Re: I admit defeat - 01/27/13 11:26 AM

"I don't consider this little experiment a failure though, because now we know for sure."

That's the way I look at experiments too. Something is always learned, regardless of the outcome.