Visitors to Don Swann's basement workshop in Severna Park are handed a gaudy, purple-on-yellow bumper sticker that reads: "Come up and see my etchings."

Swann, unlike others who have used the old line, is serious about the invitation: he has been etching for 48 years and he likes to show off his work.

Swann's father, Don Sr., who died 27 years ago, began the family tradition of etching in 1928 and later lured his son into the business. Swann remembers that when he returned from Princeton with degrees in art and archeology, his father said, "You and I should do something together, something that takes time but not too much time."

They settled on the project of putting together a two-volume book of etchings called "Colonial and Historical Homes in Maryland." The effort took five years, from 1934 to 1939, during which time Don Sr. etched 100 homes in two dozen Maryland counties, and Don Jr. wrote the descriptive text for each plate. Then-Maryland governor Herbert R. O'Connor wrote a preface and F. Scott Fitzgerald wrote an introduction.

The last two-volume book sold for $900 at an auction recently and the 28 remaining books, unbound and stored page-by-page the last 45 years in Swann's basement, will be sold for $1,600 apiece when they finally are bound, Swann says. The Johns Hopkins University Press has reproduced the book, combining the two volumes, and sells it for $35.

Swann has calculated that the amount of time taken to make each etching, using his process, is one hour per square inch of finished product. He says it takes 20 to 25 hours to draw the lines on each etching plate while looking through a jeweler's magnifying glass. "The designs are drawn inside out and backward because the printed etching is the reverse, or mirror image, of the plate," he explains. He uses a special tool of his own invention, consisting of a jeweler's holder and an old-fashioned steel phonograph needle.

Once Swann cuts a design on a copper plate, he covers the plate with shellac and puts it in a bath of nitric acid and water. Swann puts wax on parts of the plate that he does not want touched by acid. "Each bath is five minutes so that the acid bites the copper, eats into it and deepens the cut grooves. . . . It's repeatedly put back in the solution as much as four or five times so that other lines become twice as deep and different textures are attained."

The next step is the spreading of a specially prepared, oil-heavy ink into the grooves of the plate. Then the plate is placed face down between two felt pads onto pretreated paper--imported from France at a cost of $538 for 500 sheets (24 by 60 inches)--and then pressed, a process that imprints the design onto the paper. The printing is done on a 200-year-old Star etching press that Swann inherited from his father.

After printing a limited edition--300 prints or fewer --the ink is wiped from the plates. The freshly printed etchings are placed beneath heavy plates until dry.

This month, Swann is etching a series of four designs for Ridgely's Delight housing development in Baltimore, a section of older homes that are being renovated by owners who bought the buildings for $1 each.

Swann also spent 22 years as the theatrical producer of Hilltop Theater in Baltimore, during which he etched part time. He resumed full-time etching in the 1960s.

Swann has created etchings using such subjects as famous buildings, historic streets, animals, ships and boats (Maryland skipjacks especially), and landscapes, including the Wye Oak, the smallest state forest and park in the country, located in Queen Anne's and Talbot counties.

Swann lectures frequently on etching, preferring not to teach. He does, however, take on apprentices at no cost to them. The Maryland Institute in Baltimore, Towson State, the University of Maryland and a few local individuals offer instruction in the art.

Official figures suggest that there are 700 etchers in the country, but the company that sells Swann his ink has a mailing list of 2,500, and Swann says, "there are more, but very few who etch full time as a living."

Born Feb. 6, 1911, the same day as President Reagan, Swann is active at 71. A rugby player for Princeton and the New York Rugby Team in the 1930s, Swann didn't give up the grueling sport until seven years ago. He says he plans to continue supervising his gallery on North Charles Street in Baltimore and to maintain the Etchcrafters Art Guild, an organization his father began in 1929 to merchandise etchings nationally. Swann says his father was the first etching artist who sold his work in a department store. Now the family's etchings are sold in five different stores in Baltimore and in more than 250 outlets all over the country at an average price of $25 unframed.

Moving around his dank basement in the orange and black (Princeton's mascot is the tiger) robe his wife Sandy made for him, he says he is not sure that he can continue to participate in the 30 art shows and six weekend trips to New York each year that he does now.

Swann's mother, Rita, who died 15 years ago, also etched; she was the only trained artist in the family. Swann constantly reproduces his parents' etchings from their original plates. Counting his father's 600 etched plates (Swann notes that the famous Dutch artist, Rembrandt, etched only two-thirds as many), and more than 100 of his and his mother's plates, there are about 1,000 plates stored in his basement.

Some of Swann's etchings have won awards--20 to date--and Swann has been successful at the Washington Square Outdoor Art Exhibit over the years. An etching of the Mother Seton House in Baltimore was presented to Pope John Paul I in 1976 at the Vatican in Rome and a former governor of Maryland used one of Swann's etchings (without permission) for a Christmas card.

Swann forecasts a steady increase in the marketability of etchings. "I think the housing industry has something to do with it, since they are building smaller homes with smaller wall space. And this means people will be buying smaller art, smaller prints like etchings."

Should Don Swann invite you up to see his etchings, by all means don't hesitate. They are well worth the trip and Sandy Swann will be happy to show you around.