In the hope that it might help someone with a similar challenge:
My trusty Quasar was bought c.1986 and has been on many, many trips. I re-proofed about 4 years ago, but otherwise little intervention and it's always kept me dry.
However, this summer the seam tape finally started to peel off wholesale.
Online the advice is firmly in favour of seam-sealing with a glue; going so far in some places as to say that re-taping is not possible at home. I tried this using "Gear Aid Seam Grip+ WP", which was fairly widely recommended as the go to product.
I pitched the tent, and the fly insode out to expose the seams. I then peeled away all the shredding old tape. Then I got a flannel-size towelling rag, soaked it in isopropyl alcohol and carefully wiped down all the seams. Twice.
I followed the Gear Aid instructions and smeared the seams, working into the threads with the brush. This is difficult and you need to put your hand behind the seam to support. However, the main problem was that some of the seams are not double stitched. These would require three layers of glue to seal properly - either side of the stitching and between the two flaps of material: _/_
I was pretty diligent amd fairly hopeful when, after drying, I reverted the fly and pitched the tent correctly. However, a hose rapidly showed several leaks; quite disappointing. So I thought I would try taping instead.
I bought 20m of Hi-q 22mm wide seam tape (£7; eBay). It's iron-on and faffy, requiring the correct combination of temperature, pressure and duration. I have some scraps of Quasar material that came with it, and so could do some tests. 20s on a medium hot iron (2.2kW I think) with gentle pressure onto a double-folded towel worked for me. You need a piece of baking parchment over the tape, shiny side down. I wiped all the seams down again with alcohol.
It seemed easiest to do each seam in one long run as this avoids issues with the end of the tape sticking to the parchment. When it's right, the tape bonds onto the fabric and makes a clear, barely visible, stripe.
The main trouble shooting was the tape lifting when I lifted the parchment. Be really careful in peeling the parchment off. Iron heat too low/duraion insufficient. Can be easier to work from middle outwards. Go back to edges with edge of iron and increase pressure/duration. however, the worst issues were where I hadn't degreased thoroughly enough (I suspect the waterproofing treatment was still on.
The result is good - the tapes are well-bonded and water-tight. I will go over the intersections again with the glue as the tape does less well where there are major lumps. And I didn't burn a hole in the polycotton. Or in me.
Needless to say, at your own risk. Irons get hot. Isopropylol needs really good ventilation and be away from ignition opprotunities. Wear mask, eye protection, rubber gloves as needed. Your kids may get repossessed if you don't keep up repayments on the tent. Etc.
Overall, don't believe the web when it says only manufacturers can re-tape a tent.
Post edited at 21:02
