Should I seam seal this backpack? (3FUL 45L LS21)

[Niko Z.]

Hello all,

I have receiveded a 3F UL backpack made of LS21, with XPAC-21 used for the back and harness. Here is the product link and here are close up photos I took of the seams inside and out.

I have recently discovered that I enjoy seam sealing tents and have glue left over. I am considering whether to seam seal this pack and how? I have no experience sealing packs and have not dealt with this material before. It appears that it would be easier done from the inside, as the seams are readily exposed on the inside and don’t require stretching out. I would appreciate some input from knowledgeable folks on this forum.

The 3FUL online store representative said no sealing is needed, but some other parts of their reply made me think they didn’t fully understand the idea.

Best,

Niko Z.

[Niko Z.]

PS. In the linked photo album top five photos are from the outside, bottom five inside.

[John S.]

I would not seam seal and would use an inside liner.

[Jerry Adams]

I’ve sealed inside seams in packs I’ve made

It’s hard to get it waterproof though.  Sweat against fabric will leak through.

John’s onto something with the liner

Or place things on the back that are waterproof, like a plastic bag or mattress

[Jerry Adams]

If you have the sealant, it adds negligible weight so there’s no harm trying it.  It’ll probably make it more waterproof.

I made a xpac pack and after a while it developed pinholes that let water in.

[Niko Z.]

Jerry and John,

Thank you both for sharing your knowledge. It seems that the liner is the way to go.

In my spare time I might seal it to see if it helps a bit. We get about 30feet of rain per year here, anything that helps with waterproofing, even a little bit, is a bonus.

Cheers,

Niko Z.

[BPLwiia]

I have a couple of Seek Outside packs made of either XPac-21 or XPac-42.  Seek recommends seam sealing on the outside of their packs.  I found that many people who posted YT videos, seam sealed on the inside. I have not seam sealed my packs as I’ve not found water intrusion even in heavy rain. If I did, I’d be tempted to seal it from the inside. Maybe the end result would not be as waterproof but I don’t the messy look of the sealer on the outside.

Here is Seek seam sealing an XPac-21 and XPac-42.

https://www.youtube.com/watch?v=8MOThp3efq8

 

 

 

[Niko Z.]

Thank you for the link BPLwiia,

The bag in the video you have linked is a minimalist design, so it’s feasible to seam from the outside. My model has deep pockets and mesh panel, so I think I will seal from the inside when I get the chance. Otherwise things could end up looking very messy, as you have remarked.

I was thinking that on the outside there would be a lot of stretching of the seams, and not sure how well the glue would adhere to liteskin, the material appears very smooth. On the inside, bonded seems provide a textured surface for the glue to adhere to, as the manufacturer has used some textured material to bond the seams, most likely XPAC.

I am thinking however, that if I seal from the inside, I might end up needing to use the liner anyway, to protect the glue from rubbing off through abrasion. Otherwise, I am concerned that constant rubbing of items through packing cycles would wear out the glue on bonded seams.

Which brings things back full circle, if I am going to use the liner either way, is there any added benefit in sealing?

Jerry has sealed inside backpacks, does the sealant wear out if there is no liner used?

Cheers,

Niko Z.

 

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