I just got back from the fabric store. I bought 8 inches of 3 fabrics for a total of 24 inches cost $9.82. One was on clearence for $1. I need light purple & dark purple for my star blocks. I have lots of dark purple, is there anyway to lighten these up.
I refuse to go back to that store again. The LQS has some fat quarters on for $1.99 I can get better at your Joanne's for 2/$1.

Lay it out in the sun? I dunno. Just guessing here, but I know sun damage lightens fabrics over time.

I've never done it but you could search for "discharge dyeing" through google.

I googled a lady that worked in a laundry said to try dylon colour stripper.

sun fading also weakens the fabric

As bearisgray said, The sun will weaken the fabric. So will bleach.

Do you have samples of the colours you need? Maybe it would be easier to just trade for fabric with some board members.
If I have anything you would find suitable, I'm interested in trading for scraps.
Bleach discharge will not weaken the fabric too much unless you leave it way too long. I'd look around on google if you decide to go that route.
Good luck!

I did some bleach discharge thing years and YEARS ago - worked well for creating a new fabric that 'matched the one I had started with. You had to neutralise the bleach with something with a logn name - I want to say Sodiummetabysulphate - but don't know where that came from!

ANYWAY

As I can't give precise instructions - google it. I know if you do it right it won't weakent the fabric toooooo much!

I also think the swaping with board members idea is a good one!

Add a very small amount of Clorax, few drops.Dip fabric into ioxture few times and test for color. Wash the bleach mixture out and rinse and rinse.
Soaking with bleach for a long period of time will weaken fabirc.
Have you tried used the reverse side of the dark purple?

I'll ask my husband - he can screw up my clothes like no one else! Fading, bleaching, colours gone, shrunken misshapen things = he has a great deal of expertise.