How can you tell if a 1985 twenty dollar bill is fake?

If the date on the bill is 1990-present, a real bill will contain a security strip embedded in the paper. You can see it if you hold the bill up to light. Then bills 1996-present added watermarks of Andrew Jackson, which can also be seen when held in front of light. The number 20 on the front in the lower right corner is printed with a color-shifting ink, which changes color depending on the angle at which it's viewed. Something else is in the paper itself. All currency paper contains small red and blue fibers, which will be missing from fake bills. Also with the paper, bills have a distinct feel and texture to them.