Treat the bivvy after you seam tape it.
I washed my bivvy in non bio liquid then nikwax and tumble dried it hot and the tape came off it, which was the material sort of tape, probably because of the tumble drier being too hot for old tape. I tried ironing it back on, but given it had mold on the face of the seam tape, I think it was past its best. The bivvy bag was not treated, so some more nikwax, and still not treated. So I decided to start afresh by washing;
1)biological wash that does absolutely destroy nikwax
2)non bio, basically soap like tekwash or soapflakes to get rid of the bio residue,
3)nikwax to proof, on a cold wash slow spin.
4)bio in the washing machine to get rid of the nikwax in there.
Still unproofed, due to the great rinse and spin cycle I think, so warm water in a bowl, nikwax and submerge for 15 minutes, then a warm rince in a bowl to get rid of the exess, otherwise it will not breathe. Left to dry lying flat to make sure the coating did not drain off. Some more seam seal material type,(15m) and 4 hours later it was proofed but not sealed. The nikwax on the waterproof base was stopping the seam tape glue fixing. Wipe it round with meths on the base and seal. The bag has now been reproofed and resealed sucessfully.
The material is eventlite, and changes colour with the ammount of wax on the surface. It's fun and games
I don't know if it was the mix, the fabric (goretex) or something else, but it was almost 'crispy'.
