Permalac typically lasts up to 10 years on indoor structures and approximate 3-5 years on outdoor structures with a single application (3 coats minimum indoors and 4 coats minimum outdoors). Our formula has not changed, though the design of our cans has. Permalac spray cans have a shelf life of 3 years from the date of manufacture, after which they should be safely discarded. Quarts, gallons and larger sizes have a shelf life of 2 years from the date of manufacture. You should have the same lacquer, but all of our products now come with a specific designation as to which finish it is.