Answers 10 cents. Correct answers one dollar. The easy answer is, "No." You can color a dollar bill and not break the law or demonetize the bill. Abstractly, you will actually create something potentially worth more than a dollar, but that is another question entirely. The Coin World Almanac cites the relevant section of the U.S. Code. I helped write the Coin World Almanace, so I trust it.
Well, I posted this forum at like, 8:00 last night, then, with my mediocre artistic skills, colored it in.
The value might rise, but the people who value it would change. For example, I have a Silver Certificate signed by Elvis. Currency collectors would say it decreases the numismatic value, but Elvis collectors would pay more for it.
L L!! I got one of them in early summer and spent it in July, but looked crisp, colorful, and important those few weeks!
I had a hobby recently where I would have a celebrity sign several bills, I then printed their name in the margin to help identify the autograph, then I spent them (except for one of each that I kept). I got bills signed by Max Schmeling (German boxer who beat Joe Louis in the 1930s), Robert Ballard (discovered the Titanic), some Medal of Honor winners, etc. Not sure where these will end up in future years, but hopefully some were saved.
Odd you should mention this. I have a 5 dollar Canadian bill signed by a bunch of people including my wife's grandfather who was an executive at Look magazine at the time. I don't know who the other people are but I've always been curious.