Help sort out my confusion

Thomas,

Given the price limitations you listed I think you are left looking for something like nylon fabric that probably weighs about 2 ounces (e.g. 1.9 ounce ripstop) per square yard plus the weight of the coating. The coating would probably be urethane in this price range.

I only looked quickly but I couldn't find fabric like this at Magna fabrics. I agree with you about their low prices, however.

You might luck out and find something at Walmart or Pacific Iron and Metal, e-bay or elsewhere on the internet. If I was looking I'd probably search for "1.9 ounce waterproof ripstop nylon" or something similar to that.

I would definitely get something with a waterproof coating already on it.

Maybe I gave the wrong impression… I'm not having trouble finding fabric in my price range. I see some 70d DWR coated (2.25oz total so a bit heavy) stuff on magna for 79cents/yard & some uncoated 30d for .59/yard . Ripstopbytheroll has 20d DWR coated ripstop for 4.25/yd & 70d DWr coated for 3.85/yd …

I just don't know which ripstop fabric (30d or 70d) is best for making hammock tarps; or if there is something else out there in that weight & price range that would be more suitable.

Thomas,

I've used as light as 1.1 (plus weight of coating) ounce per square yard ripstop for tarps and tents. I don't know the weight per square yard of the 30 d stuff you mention but the 2.25 oz per square yard 70 d stuff sounds heavier than required.

I could be wrong but it sounds like all the fabric you list in your second e-mail is water repellent…..not waterproof. Is that going to meet your needs? I'd be looking for fabric with a waterproof coating.

SILNYLON

Thomas,

My first hit for a search of “silnylon seconds” came up with the $5.50 per yard stuff shown above. Others may offer it cheaper.

This price is only $1.25 higher than the $4.25 per yard fabric mentioned in your second e-mail.

Perhaps you shouldn’t rule out the silnylon? It is what others more commonly use for myog tarps.

I was wondering about that – silnylon was consider pretty cheap even back in the day when it was considered the best/only UL material for tarps. In fact many of the serious DIY folks on here probably have tons of it lying around. That was never me, but I checked anyway and I don't in fact have enough for either of your tarps or I would send you some free.

I suggest you try silnylon and if you balk at the price put up a notice in Gear Swap. I would be surprised if you couldn't pick up what you need way below market. Sort of like "WTB so many yard of silnylon if you have any you aren't likely to use ever again."

Unless you are specifically going for a tarp that is only semi-waterproof, for example if you will be using it in an arid environment where a long downpour is unlikely, then you may want to avoid waterproofing a tarp with Nikwax or the like. You probably want an actual waterproof tarp. The "R" in DWR is not a "P", and you don't need for your tarp to breath. Also the "D" implies that it will not be permanent. If you are really planning doing a DWR treatment on a tarp, and price is an issue, I'm not %100 sure you haven't hidden a lot of the cost in that.

The reason folks doing DIY projects often fall back on silnylon for tarps is that is is light, somewhat cheap, and more or less permanently waterproof. You just have to take care of the seams.

Use "seconds" quality silnylon, this can be found for around $6 a yard. PU coated stuff is less expensive but the coating will come off after a couple years.

thanks for the input guys. I'll try to find some sil

Thomas,
For a simple 8.5 foot square tarp of coated 190D you might want to look at this –

http://www.sportsmansguide.com/net/cb/cb.aspx?a=1145824

22 bucks, with shipping I reckon that's more like 30, but still cheaper than Equinox tarps and the like, and probably cheaper than making yer own.

Thanks, I'll check that out. I'm not looking ton!take the tarps to save money though, I enjoy making things and using the thing ive made. I learned a long time ago that day and myog projects rarely equal much savings if any… In fact my project normally end up costing more than store bought goods. I wanted to keep the price down on the materials because it'll be my first tarp and an experiment at best. I don't expect to use the tarps more than once or twice before wanting to make something bigger/better/lighter/more waterproof…

DIYgearsupply's silnylon 2nds have worked well for me. His yards are usually 60" wide or wider–5 yards will make make you an 8×10 tarp for less than $30 in materials. Sewing silnylon is a little tricky, though…

Well… I'm a beginner at best with sewing. What makes the silnylon more difficult to sew?? The slippyness?

How do you get a 8×10 tarp out of 5yds? When I do the math it takes at least 6yds. I guess you could do it with 5yds (enough sqft) but it would take multiple seams right??? I can't even figure out how to do an 8×8 with less that 6 yards. With 5yds I'd need at least 4 seams.

When you sew two pieces of silnylon together, the top one sticks on the pressure foot a little and slips relative to the bottom one, so for a long seam, they won't line up at the end of the seam. If you tightly hold the two pieces together, aligned, as it feeds into the machine, applying a little tension, you can keep them from slipping. Making some fine, precise, marks every two feet on each will help – make sure they're aligned as you feed into machine. Practice on narrow strips.

Silnylon is often 5 feet wide (60 inches). Cut two pieces 8 feet long (2 2/3 yards) for a total of 4 4/3 yards = 5 1/3 yards of fabric. Sew the two pieces together to make 8 feet x 10 feet.

Another good place to buy silnylon is at Noah Lamport. They typically sell it for $3 / yard. You have to call them on the phone and place the order. When you call ask for Roger – he was quite helpful. I think they have a minimum order — maybe 10 yards? Ask for it to be taken off the roll before shipping it – otherwise shipping is crazy expensive. There is a $5 cutting fee and shipping is kind of expensive – but not terrible. I would get a quote on shipping before committing to buy.

The slippyness, yes. Jerry's description nails it. A professional-looking job takes practice. A functional job, not so much.

And yes, my mental math was off a bit. So you prob. would have to buy 6 yards if you wanted a true 8' x 10' tarp (and have 2/3 yards left over). Or you could try 5 yards and a 7.5' x 10' and see how that worked. Granted, the seam would prob. be perpendicular to the ridge.

There are other tarp patterns (than flat) that are more efficient with yardage and provide good protection. Some people like all the different pitches they can do with a flat tarp–I prefer the simplicity of pitching a shaped tarp.

Anyway, it's not difficult to do a MYOG tarp with complete protection for something around $30 and 10 oz (or a bit less). Lots of threads here discussing variations.

"Lots of threads here discussing variations"

Guys…this is were I'm losing you. I'm not dummy, in fact I'm in IT and googling/searching is soemting I'm good at. But for the life of me I haven't been able to find many articles, discussions or patterns (other than diysupplies) on making tarps or fabric efficiency. Maybe I'm just completely overlooking it or over thinking the process. I understand that making a flat/square/rectangle tarp is pretty straight forward, but I haven't been able to find any discussion on that.

Can you link to some of these threads or articles. Please.

A pretty functional hex shaped hammock tarp – I've also used for backpacking. Very similar to the one at DIY Gear Supply.

https://www.hammockforums.net/index.php?page=blackcat

The flat tarp is a simpler form of a shaped tarp. The construction is the same — just a different shape.

"But for the life of me I haven't been able to find many articles, discussions or patterns (other than diysupplies) on making tarps or fabric efficiency. Maybe I'm just completely overlooking it or over thinking the process. I understand that making a flat/square/rectangle tarp is pretty straight forward, but I haven't been able to find any discussion on that."

Over thinking?

Rectangular tarp – cut 5 1/3 yards in half, one seam to join them to make 8' x 10'

Cut off the selvage (where there are sprocket holes on the edges from the weaving machine)

Sew the two pieces together with flat felled seam

Hem around the edge – fold over 1/4" twice and put in one row of stitches.

Sew tie-outs – get 1/2" grosgrain. Cut pieces 2" long. Fold over and sew to hem. One end of grosgrain on each side. I'd sew backwards with 2 mm stitch, forward with 1 mm zigzag, backward with 2 mm. Try to avoid any needle hole from being closer than 2 mm to avoid weakening fabric. This is pretty minimal, you might want to put in reinforcing piece, but I don't think the minimal solution will fail.

how to sew pyramid: http://chrisroane.blogspot.com/2011/02/myog-10×10-pyramid.html

Or read my article but youu have to be a "M" person

Well, others have mentioned some applications that were not really what you were asking about.

For tarps, and flys, you want the fabric as waterproof as needed without increasing weight. PU coated fabrics are generally more "waterproof" than silnylon. Silnylon is more "waterproof" than DWR coated fabrics. DWR coated fabrics are more waterproof than uncoated fabrics. All provide some measure of water resistance. Generally speaking, Silnylon is used by most light weight and ultra light campers for two reasons. It has enough waterproofness for a week of continuous rain, and, it is fairly cheap. You can get seconds from owfinc.com for 4.20/linyd (about 60-66" wide.)The bears don't care about cosmetic defects.

PU coated fabrics have better waterproof properties, but you pay in weight. Usually 2-3oz/sq/yd or more. Fine for floors, but, it isn't needed for canopies.

Ripstop prevents tears from running too far. So in the event of tying off to a tree, a solid mount, it will not shred completely like non-ripstop fabric. This has the highest abrasion resistance, good strength, and the silicone is hydrophobic, so even a few small leaks can be tolerated where they are not directly under pressure from a rain drop (then it might mist.) Cheaper coatings may mist. I got a batch of silnylon from someone on this list that leaked, new. It appeared to be incompletely covered and was quite light at 1.2oz/yd when I weighed it. It was coated, just not enough.

Cuben is somwhat better for "waterproofness", but more expensive and it has no stretch. Sometimes this is good, sometimes bad. With a solid mount it will shred along the reinforcment threads. The stake mounts, pole mounts are suseptible to additive or cumulative damage. Where silnylon will stretch, and start leaking (easily recoated with mineral spirits and silicone calk) damage is not like that. It will simply drip. It will elongate sewing stitches, soo glue is needed. Both glue and stitching is recomended. And the weight savings on .7oz fabric over 1.3oz fabric is not quite 50%. For 5 yards or less, it will only save 3oz. It is not as abrasion resistant and has issues with folding, which can delaminate/loosen folded areas. This is the second choce, because of the weight, only. It is the first choice of XUL, SUL campers because of the weight. Basically, it is two thin sheets of plastic over a few reinforment threads…more of a film than a cloth…it is termed a laminated material, not a woven one.

For general use, silnylon is usualy used for flys, with PU for tent floors. Often some mesh is used. For tarps, silnylon would be my first choice. A 3ydx3yd (9×9) tarp is 9 sqyd and weighs about 14oz. After seaming, stakes and guy lines, about 18-20oz. Note than seaming, loops, stakes and guylines are needed whatever the material.

The simplest tarp I can think of is to get a 6 yard piece. Fold it in half and cut it. Flat seam it together. Then simply hemm the perimiter. Add loops to each corner, fold and add loops to each center. Over a hammock, this will waste a bit of material where it comes down, but as a flat tarp on the ground it will work in many set-ups. For a bug net, you can tie a small stone into the material till you get the position correct, then sew in a loop as needed. Same for a center loop. Mineral spirits/silicone calk can be used to seal the seams. No waste, easy to sew.

Thanks! very informative!

Thomas C.:

A few links:

Here's a thread that discusses seams useful for tarp construction (with drawings and pics):

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=73739

Here's a couple that discuss shaped tarp construction, also with drawings and pics:

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=49480
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=47007

Location of tie-outs (and details of how to sew a tie-out) will be important, too. For location, I'd look at pictures of commercially-available tarps. For some sewing details, Jerry Adams has an article here (prob. need a subscription):

http://www.backpackinglight.com/cgi-bin/backpackinglight/myog_silnylon_floorless_2-person_tent.html#.UyHLMnlElNY

Finally, I wrote an article a while back (shameless plug) about using digital tools to design tarps–there's some design ideas there, too:

http://www.backpackinglight.com/cgi-bin/backpackinglight/google_sketchup_tutorial.html#.UyHL23lElNY

Walmart grey ripstop $1.50 a yard. If they have it buy it all. Coat it yourself.