As a general rule of thumb, I hand wash all vintage clothing. For antique clothing if the fabric seems sound, I will hand launder it, but if it's too delicate, better to just leave it alone. Here are my tips for washing vintage clothing!
10 Tips on Washing Vintage Clothing
1.] Use WARM water for natural fabrics (such as cotton), not hot.
2.] Use COLD water for synthetic fabrics (such as polyester)
3.] Polyester (and poly blend) clothes look better if they are hung to dry. I don't really know why, they just do from my experience.
4.] Make sure the sink/tub is clean before you wash your clothes in it! (I know, this seems obvious...)
5.] COLD water will keep colors from bleeding (if the fabric is colorfast) and also a bit of vinegar. I've used vinegar when washing 1940s printed fabrics to keep colors from bleeding.
6.] Only wash one garment at a time. Even if the colors are similar. It's better to be safe than sorry.
7.] Dissolve detergent in warm/hot water first, THEN add to your rinse water. I once put detergent in when the (white antique) dress I was washing was already in the water and the dye from the detergent left blue spots on the dress. I then had to wash again and soak in bleach.
8.] Don't agitate the fabric too much (or at all if you can help it). Usually I sort of just pat and carefully "knead" (sorry, I can't think of a better way to describe it) the fabric. For dresses I will try to flatten it in the tub and gently "pat" the detergent in. If it's a sturdier fabric, I agitate the fabric just a bit.
9.] Rinse vintage garments in cool water. Make sure to rinse them well. You don't want any detergent residue! Most detergents have chemicals that are fairly harmful to vintage fibers, make sure you rinse well, do it twice!
10.] If in doubt LEAVE IT TO THE PROFESSIONALS. I am by no means a professional washer/restorer of vintage clothing, so the more delicate items I let air out on my clothesline instead of risking damaging it forever.
Sometimes you can get away with throwing vintage clothing in the washing machine, after all they did have washing machines as far back as the late 1900s... Generally I only machine wash clothing from the 1960s and later.