Seam Sealing ECOPAK Ultra EPL

DCF backed tape works well and is likely the easiest option to get. I think places like RipstopbytheRoll have it.

Do you know if silicone thinned with denatured alcohol would have any adverse effects on the material?  I have a feeling that some seams I will encounter may be too bulky/not flat enough to tape (at least with 1″ tape), and wondering if this is possible to do on those spots.

I’ve used seam grip on PET backed laminates before (like Ultra). I’ve had good luck, but I’ve heard and it can peel off over time.

For tape, Quest Outfitters sells a Mylar seam seal tape that works very well and the availability is often better than DCF tape.

Most packs will not have interior seams that lend themselves to tape because, as you mention, they are not flat or are too bulky. The only real option that I have been able to identify is a careful seam sealing of the exterior of the seam. Aquaseal  works extremely well for this, if you can get a somewhat narrow tip so that you can apply the bead directly and effectively to the seam. I did my UHMWPE Seek Outside Flight 2 this way, as well as many prior packs with polyester-faced Cuben fabrics, or XPac fabrics, and the Aquaseal has always been a permanent solution in my experience. It soaks into the weave of the face fabric for good anchoring, and has enough stretch and flex so that it doesn’t break down over time.

I loosely roll up an inflatable sleeping pad and slide that down inside my pack, and then inflate it to stress the seams so that the stitching is slightly exposed as if the pack or stuffed with gear, suspend it from the ceiling, and then carefully a seam seal from the outside. It can be difficult to do a good job where there are complicated penetrations in the seam like where gear loops or water bottle pockets present you with multiple surfaces, but through one or two careful sessions of applying the Aquaseal, you can really get a lot of the exterior seams of the pack well covered. Aquaseal comes in two flavors: FD and SR. The SR is more viscous, and less likely to cause drips or runs. I generally prefer this because once you apply it, it stays put as it cures.

I would strongly encourage you not to pursue any silicone-based strategy, because if you do, once the sil adhesive fails you will never get a polyurethane based adhesive to stick to the surface again. I learned this the hard way.

I have actually used Aquaseal SR (well…when it was called Freesole), to seal up the seams of some OR “waterproof” over-gloves with good success after stuffing the gloves with paper towels and applying into the seam with a toothpick.

This sealing for a new pack will be on top of me using a Nylofume….so I may just get some DCF tape and seal the seams that are possible (probably at the top of the pack) and just call it a day.  Will have to investigate the construction more once it arrives.

Thanks everyone for your input.