try the laundry forum

and did you wash the grey one too?

exactly the same settings?

BTW - heat does cause items to shrink, not detergent.

It might be the textiles. Certain spins of cotton shrink even in cold water. Rayon is less likely to shrink, but can. It shouldn't be the detergent or water quality. Those can affect color, but don't generally do anything to shrink.

Are you sure that the two sweaters were identical in size when they were brand new? Different colors are often made with different fibers in different factories. Blacks in general tend to be a bit smaller new. This might be from dyeing them after sewing (i.e., garment dyed). Blacks are usually a multi-stage dye process where they overdye the ones that didn't come out right from a lighter color vat. They are processed more, often with heat, which leads to some pre-shrinkage, so your cold wash might be keeping lighter colors from shrinking but the blacks might have already shrunk.

Another issue is finish. Once the garments are made, they're often processed with sizing or other treatments, and are blocked, which stretches them to maximum. They look crisp and nice in the store. After a few washings, the sizing is all washed out and the garment goes limp and shrinks a bit. Therefore, the blocking and sizing might have made the black seem the same size as the gray, but if the gray wasn't as heavily processed it might actually be larger in the long run. As I said before, this is something known about blacks. They tend to be smaller for ostensibly the same garment.

This is one of the differences between a $10 shirt, a $75 shirt and a $250 shirt. I'd expect it of the first, I'd be annoyed by the second but not too surprised, and I'd take the third back and demand a full refund even though it had been worn and washed several times, because better quality and no surprises are supposed to be what you're paying for with an expensive garment. But then, the expensive ones usually just say "dry clean only" so that they're not responsible for laundry mishaps that are caused by the manufacturers' quality problems.

With natural fiber sweaters, you're best off washing in cool water, and laying flat to dry on some layers of towel. Shape the sweater to the way you want it to hang. Usually, hanging sweaters to dry can cause them to droop and sag, though sometimes being free can make a loose twist draw up. If you lay it flat you might be able to use the friction from the towel to keep it spread the way you want it.

Thanks to you both for the replies. I'll try posting in the laundry forum as well.

plllog, I am sure that the clothes were the same size before washing. The same thing happened with purple sweaters that my sister and I bought together. I have worn and washed mine, and it shrunk. She has only worn hers but never washed it. She now says that she'll never wash hers because she doesn't want it to shrink! We compared sweaters over the holiday weekend. My sweater is visibly tighter on her compared to her sweater. This particular sweater is 100% cotton so I guess it makes sense that it would shrink somewhat. I may have to start dry cleaning more of my clothes.

antss, I have not washed the gray sweater yet. I used it as my control so to speak.

The camisole that I'm wearing today shrunk and is now a belly shirt! Oh well! This is annoying problem, but I'm sure I'll get to the root of it someday.

Thanks again!

I thought I remember reading that when washing sweaters you may need to lightly stretch them out to their original size/shape prior to drying. Also they need to be dried elevated so that air can circulate all around.

All fabrics, especially sweaters, can/will shrink to differing degrees when wet and then dried. Heat will cause even more shrinkage. Natural fibers are definitely more prone to it which is why wool and silk garments often advise dry cleaning.

You can try stretching after washing and then laying it flat on a towel to dry. Also, try rolling it in a dry towel after washing which does two things... it stretches it slightly and it also pulls as much water as possible out of it. Then lay flat on a fresh dry towel to finish drying. Once it's dry, if it feels stiff or not as soft, then put it in the dryer on "air fluff" (no heat setting) and tumble it for 10min or so. If that doesn't work or is too much work, then try dry cleaning.

What made my clothes shrink are 'calories'.

What are calories?
Calories are those little buggars that get into your wardrobe at night and sew your clothes tighter.

MY CLOSET IS INFESTED WITH THE LITTLE $HITS!