Last evening, I finished off a storage bag for my folding Sawvivor saw (draw string top, pocket for spare blade, nylon that I treated with silicone spray to waterproof).  Now I'm looking to take on something a bit bigger ... a 10 X 10 Silnylon tarp.  I have some silnylon yardage on order, but I had a question (or ten) about construction. 

My aim is to keep the total tarp weight under 1 lb.  The 1.1 oz (1.3 oz after silicone treatment) silnylon material comes in at about 9 oz.  The plan is to use flat felled seams to join panels and a "rolled" seam for the edges.  Are those the best options?  What seam allowance would you use?  I'm thinking 1 inch.  Do you have a preferred light weight tape material that you would recommend for tie-outs?  Would you "double" the tie-out points with an extra patch? Would you place tie-outs at 2 foot intervals (at least those opposite the ridge-line) or do you prefer 2 1/2 foot?  Would you use nylon or polyester thread (and what weight)?  Other than the ridge-line, would you re-seal sewn areas?

Any other design options you would consider for pitching versatility?

dd

DD,

My wife has made three silnylon tarps for me, two 10X10 and one 8X10. The center seams are about 3/8 to 1/2 inch flat felled and the edges are about 3/8 inch rolled. The seams are not taped. The tie outs are 5/8 or 3/4 inch grosgrain ribbon sandwiched between the tarp body and small tabs of silnylon to reinforce the stitching. I bought nylon thread, but it was too heavy for her machine, so she used cotton coated polyester thread. To seal the stitching, I dissolved 100 percent silicone windshield sealant in Coleman fuel and painted it on until the threads were saturated. When the solvent evaporates the silicone is left behind in the thread and needle holes. They have not leaked yet. I don't think you can have too many tie outs so she put on a lot of them. I have even had her add more along the center seam that were not originally there.  They have stood up to those crazy prolonged winds in Quetico on several trips now with no signs of weakness. The attached picture was taken July 2008 on McAree during one of those two day blows. 

Pat

dd,

I'm not sure what weight silnylon that is. I found it a few of years ago at Wal-Mart in the discount material bin for $1.00 a yard. It was labeled "unknown synthetic" or something like that. I bought a bunch of it. The 10X10 tarps weigh a pound and a half in the draw string stuff sacks my wife made for them. Just under two pounds with ten stakes included. I use Easton aluminum stakes and aluminum gutter nails. My wife has also made several stuff sacks and a paddle coupler from the material. This picture was taken at the same place the following year. I have used the tarps more as wind breaks than as overhead cover in Quetico. That nylon camo tarp on the right didn't fare nearly as well in the winds as my homemade model.   

Preacher wrote on Nov 17^th, 2011 at 2:46pm:

Yes.  This is the way I would probably do it, although there are a variety of solvents suggested for liquefying clear silicone.

Pat -

What ratio did of solvent to silicone did you use.  I've seen rates ranging from 3 to 2 (60/40) to 3 to 1 (one quart solvent to 1 tube silicone).  I would think the thinner mixture would be easier to spread and would more readily seep into the stitching.

I've seen a variety of youtube videos of individuals taking non-treated nylon (and other materials) and dunking it in this mixture to create their own silnylon (etc.), but I've also seen photos of sil tents going up like a torch.  I'm assuming that you would use the least flammable solvent you could get away with (although they all seem to be flammable at some level) and let it evaporate as much as possible.

dd

Here is a link to a site with a good tutorial on making stuff sacks. The square bottom makes them a lot more useful than just sewing up a sack like a pillowcase. My wife has made several of these for me:

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Pat