I would like to know how I can clean a silk tie at the knot. I presume it got filthy, over time, due to "fatty" fingers. I am looking for answers either based on 1) good theory or 2) personal experience. I am not looking for grandma's advice.
Dry clean a soiled tie at a commercial establishment. Bombyx mori pupae died for our ties. While you are here, learn to tie the knot. Practice with a cheap polyester expendable resource.
177,147 ways to knot a tie.
A Trinity knot has no small end, removing the need for a tie tack. It is a full Windsor tied with the narrow end, plus two steps. Set the broad end where you want it, for it stays there during tying. The very first thing you must do is pinch the neck location into a dimple where the first bight wraps. The diagram is otherwise complete. The Matrix Reloaded Merovingian or Ediety Knot ("a tie wearing a tie") is a full Windsor that begins with the seam side showing. Tie it, loosen, pull over your head. Reverse it seam side down, put it back on. It must be worn with a vest. You may now be seen in public.
For Referees - When you wear a suit, wear a tie knot that makes you better than the opposition.
I am not sure if this falls into the grandma advice category, but when visiting silk shops in China, one of the guys claimed that the silk threads was similar to human hair, and one way to test if something was real silk was to try to set fire to a tiny part of it, it should smell like burnt hair. And that using a hair shampoo was good for washing silk.