I have sewn several MYOG items using silnylon or other coated fabrics. However, I'm about to sew a bivy with a DWR ripstop nylon top.

Is it best to sear or heat seal the edges of the uncoated fabrics so they don't unravel over time?

Thanks!

I find it so. I cut the material with a "blade" attachment on my electric soldering gun. In order to cut straight lines I use the gap between the boards in my deck. Works great and seals the edges of the cloth very well.

It does not take long to run the edges back and forth a foot or so at a time through a candle, but be alert as nylon is flammable. I do not believe it is necessary to sear the edges if they are not exposed. In other words, you might roll the edge under as in a rolled seam. In a felled seam the edges of the fabric are also rolled under and not exposed. The edges will be exposed in a flat seam and then the fabric could later fray. Seared edges will help prevent the fraying.

I've used a "woodburning" tool from Walmart or other craft place. The thin blade works well - cuts and sears (melts its way through the fabric). IIRC only costs about $9.

For cutting I use a $6.00 Weller souldering iron and a brass adapter, about $3.00, called an HK11 that will sandwich in any kind of exacto blade or scalpel blade. The cheapest weller iron takes screw in tips and that is what the HK11 is. the HK11 is exactly like a pin vice adapter.

This set up works great.

I have found that heat-sealing the edge of silnylon is not worth doing and does not work very well anyhow. The silicone alters the behaviour. If needed, I hem it. But PU-coated nylon is another matter.

Heat sealing nylon with a hot knife (as described) works well. Doing it with a candle or Bic flame works ... but is rather unreliable. Either way done the sealed edge has a limited life as the melted nylon does break up and start to fray. I heat-seal Cordura as a matter of course, but for the rest I find hemming to be better.

Cheers

Another issue to consider is hot knifed edges can be slightly more abrasive than a plain cut edge. The melted nylon forms a thin, hard micro-bead of sorts as opposed to the softer plain cut. Depending on the location, the seam may, over time, damage some of the nylon around it if there is any sawing type movement of the seams. If the seam is folded in and the edge left unexposed there should be minimum fraying problems.

Mike

Thanks for your replies. I will sear the edges of the uncoated ripstop or Momentum with a soldering iron w/ blade that I have. I'll be using the fabric on a Bivy top sewn with French Seams.

http://www.thru-hiker.com/workshop.asp?subcat=11&cid=87

Dan