Just dip them in Lux suds every day. Lux keeps the silk nice and springy, so it doesn't break so easily into runs.
10 seconds sound clip from the The 39 Steps (1937) classic radio play.
You can hear this line at 00:18:43 in the radio play.
Quote context
[...]
- More secrets, Betty? The house is full of them.
- Now the door is closed, we can talk.
- Aunt Sally, what can I give Mother for Christmas?
- Yes, and she just says all she wants from me is love and kisses.
- But she always says sheer stockings are extravagant.
- Not necessarily, dear. They wear very well if you're careful about washing.
- I'll buy a big box of Lux and give it to her with the stockings.
- Now, that's a real Christmas gift, Betty.
- Okay, I'll get some Lux Flakes right away.
- And be sure to use nothing but Lux Flakes, dear.
[...]