I purchased a kit for twin size bed for dgd which consists of a white tone on tone background and all the fabric which came with it are fat-eights (there are a total of 90 in all). They are all BRIGHT colors. I feel these fat eights are too small to put into the washing maching. I remember reading another post long ago about some product to use to prevent bleeding but I can't remember what it was. Also, would you use these products after completing the entire quilt or should I soak in a tub before putting together? Please help - I don't want to take a chance of all these colors bleeding on the beautiful white background.

You will need a product called color catcher. It is with the laundry detergents. I would swish them around in your sink and see if they bleed. I wouldn't put them in the washer.

If you wash the fabric before you start the quilt you may end up short on some of the fabrics. Kits are notorious for having just enough to cut your pieces from. Finish the quilt and then wash it with Synthrapol. It will suspend any excess dyes and keep them from attaching to the white fabric.

What about washing them by hand. I do that in my kitchen sink and then rinse them until no more color comes out. Then I roll them in heavy towels to soak up water before ironing. This seems to keep them from fraying too badly, also.

You can test by taking a small piece from each fabric (about 1-inch square is enough) and placing in water for a few hours to see if it bleeds. Afterwards, rub a white cloth over the wet fabric to see if any dye "crocks".

I don't usually do this. I probably would if I were mixing reds or blacks with whites. All I usually do is wash the quilt in Synthrapol the first time.

Even Synthrapol won't stop a heavily bleeding red fabric from tinting other fabrics so, to be on the safe side, you might want to test any dark red fabrics. Just from clothing, I have noticed that blacks are often not stable too.

If after washing a completed quilt you still have bleed through use Zout. It's available in the detergent aisle. Trace the bleeding seam allowance with the Zout and re wash (gentle cycle is fine) and then dry.
How do I know? When doing a white and red quilt, the Hoffman red bled onto the white. I had pre washed and dried the fabric, too. The Zout worked! This experience has reconvinced me to always prewash my fabrics!

i use Retayne on my fabrics to prevent bleeding.

you use it in the washing machine and how much depends on the amount of fabric and watering you're using.

all the directions are on the bottle.

Wet them in the sink with a handful or two of table salt and a color catcher. Be careful, if they shrink the pattern won't fit together. I'd do one first. Use cold water and air dry. Make sure you run them under cold water to rinse the salt out.

I just picked up some scraps at a LQS (for .25 a piece - YEAH) and put them in a lingerie bag and threw them in with the laundry. No shredding, worked well.

I love the shout colour catchers for that reason. They look like a dryer sheet but you just throw it in and you are good to go.