It's not just for the Hippocratic Oath. It also works pretty well as a rule of thumb for antique and rare textiles.
Meet my silk oriental rug.
I've had it about fifteen years, and it's certainly not antique. But plenty rare. (Or at least damn hard to get in this country, which amounts to the same thing.) The husbeast bought it from the person who wove it, almost right off the loom, as a gift for me. He was in the United Arab Emirates at the time, with the US Navy. The import duty on it would have probably been ten times what he paid for the carpet, but he worked some military magic, and, um, skipped that whole pesky customs issue. (Probably the only good thing about touring the world on board a US Navy vessel.)
Near as I can tell it is hand woven with cotton warp and weft, and silk knots, at about ten knots per inch. (By Middle-Eastern standards, the 'gauge' is positively slap-dash. I'll take it.) There are about fifteen colors in it, I assume synthetically dyed.
For about fourteen years now, it has needed cleaned. Cleaning oriental rugs is never an easy or cheap proposition, but you add in the silk issue, and, well, I would have conversations like this:
ME: Hi, I've got a silk oriental-
GUY AT CLEANING PLACE: -click- hangup.
Or a variation.
ME: Hi, I've got a silk oriental rug I need cleaned?
GUY AT CLEANING PLACE: Where did YOU get a silk oriental rug?
ME: My husband bought it in the United Arab Emirates-
GUY AT CLEANING PLACE: -click-
I assume there's some value and/or risk attached to this thing.
So for over a decade I've known I needed to clean it, and been afraid to do it. But in the last year or so, I've been reading like a fiend about textiles (y'all may have noticed) and I came to understand the physical structure of the rug. Thanks to the (failing) dye biz, I also came to understand the properties of silk, and realized that like wool, silk is really quite strong so long as you avoid a few simple things (extremes of Ph, and heat over 180F/82C). Modern detergents are all Ph neutral, and I was pretty sure our carpet cleaner didn't GET that hot (manufacturers dislike high heat, because people get burned and sue them).
That left the only OTHER issue, accidentally shrinking the cotton warp threads and having the whole thing buckle like pavement in spring. But I thought I could avoid that.
So, today, I finally found the courage to clean the carpet.
It's wet in the photo, but I think the colors are more easily discerned. The gunk poured out of the waste tank in the cleaner means it HAS to be cleaner; whether it's VISIBLY cleaner is a whole other issue. (I considered for one brief moment taking a photo of the crud, but reason prevailed.) I never got a clean tank of water off it, meaning I should have another go at it next weekend, but it'll probably take me another year to get my nerve up for another go.
All else aside, as you see, the carpet didn't buckle from shrunken warp or weft. The silk still has its luster (which means it likely also still has its strength). The color hasn't faded. I didn't suck off huge hunks of fiber. I'm calling it a success.
I think I'm going to go swoon now.