One 1920 portrait may take its composition from a painting by Whistler.
Each pin-up portrait takes between forty and sixty hours to finish.
Eight portraits taken from 1967 to 1989 round out the exhibit.
The portraits usually take two or three months to complete, she said, and prices range from $3,000 to $6,000, depending on size.
There is some evidence that the portrait may have taken a number of years to complete, accounting for the uncertainty.
Each portrait took Mattison approximately 6 weeks to complete.
"People really love him," she said, "but the portraits take a real beating out there."
Every portrait takes its place on a spectrum between the social and the personal.
An easy portrait, with few complications, might take as little as a week, but two weeks is more likely.
Between 1900 and 1915 these portraits took on a sketchier, looser style, although still highly finished.