Hi PK, well that sounds like a drag. Honestly I don’t know why things like this happen….but you did the right thing…you chucked the darned thing and had all your wraps on the other side. Brilliant. Next time, if you need a floating selvedge use the silk, it will be much stronger. You probably don’t them both. Hope this helps and well done :)

Update: I have since made another lace scarf in blue. I did some things differently and thought I would share in case it helps anybody.

1. I added 12 gauge bambu to the floating selvedges, and also the first thread in. Meaning, the first and last two warp threads were double with the bambu. I sleyed those double threads in their own dent, then sleyed 2/dent as for 20 epi.
2. When warping I sprayed the linen with water before advancing at each turn. So, pull-spray-pull and check that the threads are neat-then warp on to the back beam.
3. Before threading I took each bunch, sprayed with water and gently brushed out using a mid strength bristle clothes brush.
4. I sprayed the sections before the tie-on.
5. While weaving I kept a moist pillowcase towel over the back beam and sprayed each section with water before advancing.

Take home message:
1. The bambu held the entire warp. The right linen floating selvedge broke while weaving the header, the left 2" into the scarf. No idea about the right side, but I hit the left side with my shuttle and it broke. No idea if the second double warp thread did anything but it did give me some reassurance while weaving.
2. I feel the warping on had better tension.
3. Definitely good to spray before threading. And keep the bunches small. That makes it easier to separate the threads for each heddle.
4. Tie-on wasn't a problem before but I was on a roll with the water spraying so thought it couldn't hurt!
5. No broken warp threads and the PW consistency was better. Selvedges, too.
6. Another thing I noticed that helped: advance the warp frequently to have a larger shed. That way you won't accidentally hit the floating selvedge (or any warp threads) with your shuttle and break a thread. I advanced after every section: 2" PW, lace section, spray with water, advance.

Still not 100% happy with the selvedges - I have some loopy loops especially in the Canvas areas. But it was a much more enjoyable weave with no fretting. Next time I will only use the bambu for the floating and may keep the double first warp threads for comfort.

Great advice. I learned this the hard way, breaking a few warp threads by throwing the shuttle too vigorously. The spray and advance method works well.