Vintage Gore-Tex versus McNett Seam Grip

Age does not come alone, I have been discovering this over the past few years, and the passage of time also weighs as heavy on your gear.
As much as I enjoy my vintage Gore-Tex most of it has required some maintenance to keep it reliably functional and the biggest issue is the seam tape.

Back in the day the tape was big and wide, it sealed the seams but it did reduce the area of breathability and modern micro tape functions better from that point of view as well as being more flexible, I’m not daft.
The old taping has a familiar wear pattern, around the body of the jacket the tape stays stuck but the edges get a little abraded, unless you have a waist drawcord along which which the tape can peel with the extra pressure and accentuated wear from the concertina effect of the fabric when worn or just left tightened.

The hood however takes a beating. The concentrated 3D shaping in a small area, the tension from multiple adjusters, the constant movement, the pull of a rucksack straps, it all conspires to loosen and peel the tape from the neckline and the rest of the hood.
Sweaty necks are another thing her as well, it attacks the fabric and you can get delamination. The three layers separate leaving the Gore-Tex membrane stuck to one of the other layers. It doesn’t necessarily leak I have discovered, but the membrane is going to be vulnerable to abrasion from movement and it apparently makes professional seam repair troublesome.

Given that I have a bunch of old jackets that I wear regularly I looked at getting some professional retaping done. It was outright too expensive, especially for fixing more than one jacket which I really had to do. The repairs would be more than picking up a replacement jacket on ebay – only old The North Face and occasional Berghaus (who ever dreamed that a Mera Peak would be collectible…) go for big money.

I looked around at the options. I’d done iron-on seam tape many years ago and it was rubbish, there’s a more modern version but I really wanted to patch what was there as the bits that were still stuck were secure.
McNett Seam Grip was the one that came up all the time, approved by Gore even. However after reading a great many reviews I wasn’t sure at all. Some folk said yes please, some folk were sitting crying in their kitchen with their hands covered in glue and ruined jackets.

I decided that the truth was probably in the middle somewhere and reading between the lines a little it seemed like the best results were done with preparation and patience. I have both of those available, so I decided to try to fix one hood, the one that needed it most, on a ’98 Karrimor Summit.

Preparation and patience are vital, it took me over two weeks to fix that hood, including redoing an early bit after I got better at it. But it worked really well and after months of regular wear I stopped checking the inside of the hood to see if it was coming apart again and I just wear it.
Maybe longer term it’ll need some further patching but that’s okay, I’ve gotten used to the smells of the chemicals now and have moved onto fixing other jackets.

I reckon seam sealing works if you do it right. It helps extend the life of old gear which has got to be a good thing financially and environmentally and also it’s er, fun.

Here’s what I do, demonstrated Haynes manual style on a mid 90s Karrimor Diamond Jacket, their top end mountaineering shell back in the day in what feels like Taslan Gore-Tex, a tough 3-layer fabric.

Wash the jacket, rinse it well and gather your tools.

Rags are best, not paper towels for the first cleaning part, they will come apart leaving little bobbles of paper all over the work area.
Rubbing alcohol for cleaning. I had industrial stuff I could use at first but when that was finished I thought I’d try stuff from the chemist and it’s fine, what ever additives are in the domestic version don’t affect the results.
A little tub for the sealer and a small paint brush because the one that comes with the tube is rubbish, throw it away.
Tape, properly sticky tape. The thin duct tape I use would pull your skin off if you put it the back of your hand.
McNett Seam Grip. Under a tenner from GoOutdoors in Clydebank.

Prepare, I can’t stress this enough. Clear the area, get your kit sorted, get strips of tape cut so you can grab them and remember this – the jacket has to go somewhere when you’re finished. That somewhere has to be where it will sit undisturbed and unstressed for at least 48 hours.

Once you’re sorted identify what you want to fix first. Don’t try and do it all, especially if there’s a lot of continuous tape failure, be patient.

Below is the neck seam, it’s pretty bad on the Diamond and I’m doing it in several pieces.

Wet your rag with the alcohol and get rubbing. Don’t be gentle either, lean on it and you’ll see old adhesive bobbling off as you cut through to the fabric below.

Above is after a few minutes of rubbing and it’s as good as I can get it. You can see a shadow of the old contact area but it’s clean. I also cleaned the tape above and all the other surfaces that are being bonded just as carefully. Not being half arsed here really helps.

Leave it be and let it dry, watch some telly, have a cuppa.

Put a little seam sealer in a cup or tub, even a bigger plastic bottle top would do. Squeeze a bit out from the tube and put the lid back on. The sealer now has a limited life, they’re not joking, the tube contents will now start to cure. They say it’ll last two months if you keep it in the freezer and I’ve got to three months on this tube although the contents are definitely thicker so this was it’s last outing. Use two months as a guide, it seems about right. Stick it in a zip lock bag, stick in the freezer after use.

Paint sealer on the surfaces to be mated. Don’t go crazy with it and don’t scrimp either, a light but even coating. You want to have a good adhesive surface but you don’t want to squeeze a lot out when you mate it all together. You could even try it on scrap fabric, bits of paper, anything at all to help you judge it.

Once the surfaces are coated, press the tape back down nice and gently. The tape will stretch and the fabric will not, it’s easy to make creases in the tape if you’re overzealous here.
Smooth it out, some sealer will squeeze out, hopefully not too much and wipe it clean along the direction of the tape with a bit of paper towel. It doesn’t have to be as out of focus as it is below.

Duct tape the repair, overlapping the fabric and original seam tape with your duct tape as evenly as you can to get the glue surface in the middle. This is partly for security and also for getting it right on longer runs, if you get into the habit of keeping it centered it’ll help here.

Rub the duct tape flat so it has good grip, if the tape is well stuck your repair is well stuck. You can see the edge of the Gore-Tex tape showing through my duct tape below, this is good.

Put the sealer in the freezer, wash the brush and tub out with the alcohol, stow everything safely. Go about your life.

48 hours, I’m not joking. Stick the jacket somewhere where the repair is sitting without pressure or unwanted flex and leave it for two days. Or more, just not less.

Above I’m peeling the duct tape back off and I’m doing it in a very specific fashion. I’m pulling it away from the repaired seam and keeping pressure on the repair with a finger while I’m doing it. It’s vital not to stress the repair while taking the tape off, especially when the duct tape as is sticky as this.

Even after two days you might find the edge of the repair hasn’t completely cured, it might be tacky. That’s fine, leave the jacket where it is for another day.

When the repair edge is dry, clean off any excess sealer with alcohol and a rag, rubbing along the line of the seam tape so you don’t stress the edge of the repair.

It took a me a few attempts to get this right and I’m used to making and fixing on a daily basis. Glad I stuck with it (ha), it’s brought some of my favourite kit back into a usable state.
It really is a very doable thing. Repairing your own gear is enjoyable and brings a wee bit of self satisfaction too.

Remember, preparation and patience.

That jacket below, the whole hood has been patched and so far, looking good.

7 thoughts on “Vintage Gore-Tex versus McNett Seam Grip”

  1. Thanks very much for this. I bought a Gore-tex Bivvy Bag recently (made by Mountain Range of Alston. Cumbria, it seems) and it’s great – unused – but some of the seams are coming away…so now I know what to do!

  2. Ah, happy to help, good luck!

    I remember Mountain Range well, they did a bunch of Gore Tex bivvies and jackets, see some of their stuff on eBay now and then.

  3. Thanks for such a thorough explanation and for sharing your technique! I’m trying to figure out what to do with the taped seams on a vintage Berghaus jacket I’ve bought cheap – jacket is in beautiful condition and I love it but neck seam tape is disintegrating! It’s a plasticy/siliconey feeling tape, rather than fabric backed as these look, so I feel like I need to replace the tape itself rather than glue it back down, but we’ll see!

    1. Thanks, glad it’s helping!
      It’s worth a try on your Berghaus I suppose, the repair will clean off with the alcohol if it doesn’t work too well.
      My repairs are still going strong through wear and wash, definitely worth doing.

  4. Thanks for this info! It really helped when planning and executing re-attachment of a few tapes (hood and shoulders) on an ex-Austrian Army triple-layer goretex over-jacket. I’m using Stormsure, as that is what I could get. I believe it is pretty much the same stuff – moisture curing non-foaming rubberised clear polyurethane.

    I took a few goes to get around all the seams, as doing the curved hood is awkward and best done in stages. Between gluing I stored the glue in the freezer, as recommended. Only during my last round of gluing did I figure out that if you really do warm the glue up it is much runnier and easier to apply! Before that I was diluting it a bit with isopropyl alcohol, which worked fine. For others then, if your glue is looking thick and waxy out of the tube it might want to warm it up a bit. After sticking the tube (still in the ziplock) in my pocket for a few minutes whilst I prepped the seams, the glue was then transparent and runny, and much easier to apply!

    Now we’ll see how the seams survive during their outing in Norway, and then later a wash and retreat…

    1. That’s brilliant, hope it works out over the longer term. I’m working on waterproofs for a TGO review and seeing the prices for this year and next I’m more convinced than ever that repairing your old kit is the way to go.

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