Black Fabric gone bad... a warning!

32.5" X 32.5"      "The survivor!"

Well it looks gorgeous!!
This is the Binding tool quilt pattern. My bee had a sort of  retreat, where we gather to sew together for two days and use the same pattern with our own choices. Read about my fabrics HERE 
Some of you said you'd like to see what I made with those scraps.

I fussed over batik strips, carefully choosing a gradation of not only color and pattern, but light to darks. Cut them out with the binding tool. Cut out black for the background and made kits ready to go on Monday.

I dragged all my paraphenalia in and set up for a good day of just sewing my kit and visiting with my peeps.

First the machine acted up. That problem was solved and I went on to piece 6 big blocks. I went home to trim them to 16 inches.

Hint, if you make this, cut those setting triangles larger than Ginny says to cut. At least from a 9.25" square.


The next day I took in the center all pieced, and four more blocks ready to trim. When I started another block and had to rip a poor matched join, I noticed the black fabric had torn the length of the seam. Hmmmm. I sort of pulled gently on it and it tore like tissue paper.
WHAT??
Then I tested another piece, and just barely touching it, it also tore like paper tissue.
O.M.G.
I tested a setting triangle on one of the recently finished blocks, and yep, tore easily.

After washing it is the same strength

 Like wet paper towels.

Panic set in. I looked at the pieced four block 32" section (at the top pic) and imagined tearing it all apart to remove the apparently rotten fabric.

I have lots of older fabrics in my collection and have never had one become brittle. I do get some fabrics at estate sales but never thought to test it.

I pulled out all my blacks, and people let me tell you in case you weren't aware, there are MANY shades of black.


All of them behaved like regular fabric except another 3 yard piece that resembled the one I cut. It also fell apart.
It has a new home...

Soooooooo
I angrily ripped out the offending black from the four unset blocks.

now I am not sure what to do. I don't want to waste the gorgeous one of a kind scraps carefully cut and placed in arrangement. Pieced. Done. I had planned to surround the center with 8 other blocks like an enormous star, plain black in the corners, to make a 64" lap quilt.
I wonder if I should tear it all apart?
Should I try iron on stabilizer and leave it this size as a wall won't get stressed?
I guess I need to cut new black pieces for the 8 blocks not finished, and can make them into something larger with the existing one left this size.
I just don't know if it's stupid to keep going throwing more good fabric after bad in the finished piece.
Does one rotten apple (yard) spoil the barrel (quilt )?