When is a scar considered old?

It's all relative. : Scars last forever. They don't go away. The amount of collagen peaks after a few weeks and is remodeled, but the scar is permanent.

Old = Matured: Old means = fully matured -when the skin continuity is broken by a cut by surgery or by injury > body forms scar tissue to unite the ends. There are three stages of the scar 1 stage of healing (two weeks) 2. During the next eight weeks (proliferative stage) the scar overgrows and the scar is red, raised and lumpy 3. Maturing stage-scar becomes soft, pale and flat-6 to 12 months (longer in children).

Mature?: An injury causes a long cascade of events that promotes healing and eventually leads to a mature, stable scar. For adults the process takes a year on average, with a range of 6 moths to 2 years. For young children the average amount of time to form a mature scar is 2 years.

1 year: Scars typically reach full maturation or are considered "old" after 1 year. The remodeling pathway can continue up to 18 months however, the changes are usually more on a microscopic/histologic level and do not translate to anything that can be seen by the naked eye. You can assume that at the year mark, this is basically the final appearance of the scar.