how to whiten aged white fabric
 

I have been fortunate to come by a totally cross-stitched queen size quilt top. It is beautiful but it is apparently quite old and has been stored in a cardboard box. The white fabric has become yellowed. I have now finished the hand quilting and ready to "hopefully" get the yellow out. I need suggestions, please.

well there is one product called Restore for fabrics that is supposed to work well.

Take care when washing. Old embroidery floss colors can bleed and ruin your beautiful work. I would suggest testing a small place on the quilt before attempting to wash the quilt. Then wait for more suggestions here from other board members with their suggestions about how to brighten the white of the quilt. Hope you show us your end product. Love to see old quilts and particularly those who have been lovingly been completed or restored.

Retro Clean is highly recommended just for that purpose.

I used to use "all-fabric bleach" - not a chlorine bleach, I think it was sodium perborate. Hard to find in the stores now, it was a powder. If all else fails, you might consider tea-dying it.

I already have Biz and OxyClean on hand. Are these appropriate for using on this?

RetroClean is a wonderful product. I've used it for years on vintage quilts and other dingy things. Good stuff!
When I use it I let the item soak for several days, swishing it around occasionally. It really works and doesn't damage the fabric.

I had much better success with RetroClean.

Sun bleach maybe?

I have a white quilt!
I want to share with you what I did. I did look online for RetroClean that several of you recommended. It is available at WalMart but I didn't find it on the shelf at my local store. I resorted to what I had on hand. Therefore--Dawn to the rescue!
I used hot water in my washer and a generous 1/2 c of Dawn. Sloshed it around pretty well with intent to let it soak "indefinitely" but the manufacturer of my machine thinks they know more than I do about operating the thing so it wasn't long that I found it drained! So I filled it up again and put Biz in this time. This application went through a usual cycle on delicate and then I washed it with my usual detergent and it came out like it had never been so ugly.
I am thrilled! I hope the woman who did all of the cross-stitching is looking down on it and is as pleased as I am. It is beautiful. Unfortunately I have never posted pictures here and don't know how. Just trust me, this worked!

This is a great site. Instructions I use to clean up my antique & vintage linens.
http://www.antique-linens.com/laundryTips.html

Lisa Capen (Lisa Capen Quilts) often washes yellowed feed sacks then lays them out to dry on the grass as she says the chlorophyll in the grass provides natural whitening.

Yes, Cynthia mentions that too. Plus the sun whitens. I do my older white fabric items this way.
I tried soaking in bathtub, but didn't care for the process. The dirty water is difficult to drain well and remove as much as possible from the fabric you're cleaning.
I get one of my big plastic bins to place in tub. Makes rinsing with fresh, clean water much easier. Squeeze like a milkmaid then lay out on grass.

I have used Oxy Clean on several vintage pieces and have had great results. I put the quilt in a laundry basket with open spaces,
prepared the oxy bath in the bathtub, left it in there for a day, but swished the basket around every couple of hours. I was pleased with the product on other problems, too.