Join Date: Sep 2014
Yes, red rust is recent, active rust that is progressing fast into healthy metal. It appears on both old and new blades.
Black-ish rust is stable ( does not progress into healthy metal) and even offers some protection agaist red rust.
However, while black-ish rust can be seen as a sign of age as it takes more years to develop (but it can appear also after about 4-5 years) red rust can appear at any time and cannot provide any indication about the age of the blade.
HAPPY NEW YEAR!