Donald Cresswell wants to make one thing crystal clear.

Ellsworth’s first ever antique appraisal day, to be held at the high school cafeteria on Tuesday, Aug. 3, is not a summertime stop on the wildly popular WGBH series “Antiques Roadshow,” where he has appeared as guest appraiser.

“The road show is fabulous, you meet some wonderful people all over the country,” said Cresswell, a world-renowned authority on antique prints, maps and other paper items and proprietor of the Philadelphia Print Shop since 1981. Hopeful hordes clutching Carnival glass, Winston Churchill autographs and anything else they believe has value line up for free on-air appraisals; only a few are actually televised.

By contrast, Cresswell said, admission will be charged at the Ellsworth event to benefit a worthy cause: the Colonel Black Mansion Conservation Fund, which aims to garner enough cash from the $10-an-item appraisal fee (five-item maximum, verbal appraisals only), and admission charged to hear lectures by Cresswell and other authorities to help conserve and inventory the contents of the 1820s brick Ellsworth mansion.

Handbills promoting Appraisal Day make it clear this will be a quality event. The seven appraisers are experts in their fields, trending toward the upscale antique. John Lynch, senior vice president at Union Trust Co. and a longtime trustee of Hancock County Trustees of Public Reservations, which owns the museum, invited them and guest lecturers with an eye toward diversity. All of the appraisers are donating their services.

In addition to Creswell will be Michele Caron of Portland, an authority of gilded frames and other gilded objects; Robert Croul of Newburgh, a general appraiser of American and Continental furniture and objects of art; Michael Connors of New York, an expert on Colonial West Indian Furniture, American, Continental and English furniture; Trudy Rosato of the William Doyle Galleries in New York, who will consult on 19th and 20th century paintings, drawings and sculptures; and Cornelia Montgomery of Peter Pap Oriental Rugs Inc. of Dublin, N.H., and San Francisco.

Also in attendance will be David Johanson of Nelson Rarities Inc. of Portland, appraisers of estate jewelry, silverware, pottery and porcelain.

“A lot of the collectors wear the jewelry,” Johanson said, “but for many others it’s a thing of the past. The Victorian look isn’t really fitting with today’s lifestyles. We’re too busy to put on black tie and tails.”

Without Lynch’s enthusiasm and passion for the Black House, a museum which sits on 180 acres — Col. Black, a land agent for the William Bingham estate, enjoyed a 300-acre area — appraisal day might never have happened. He said he bumped into Cresswell, a former college friend at Belmont Abby College in North Carolina, at an antiques show in Blue Hill last summer.

“We renewed old acquaintances and got together for dinner,” Lynch said. “I later brought Don to the Black House, took the tour, and said it would be great if he would do a general inventory, a condition report, cataloging, appraising, as a basis for conservation.”

Things came together on Oct. 12 when Cresswell returned and went to work. He left for Philadelphia two days later having appraised about 60 items, eventually totaling 110 pages. Some of the treasures his eye stopped on are massive wall maps, rolled up in storage, by Moses Greenleaf, Maine’s first mapmaker. Another treasure is a large steel engraving by Baron Jolly showing Benjamin Franklin at the court in France in 1778 alongside Marie Antoinette and King Louis XVI.

“Some browning in center,” Cresswell tersely noted on the page devoted to the item.

If all goes as planned, Lynch explained, Appraisal Day will be a stellar event dovetailing with the Academy Antiques Show at the George Stevens Academy in Blue Hill on Aug. 4, 5 and 6. The show was started in Ellsworth 60 years ago and is known as America’s longest-running antiques show.

“My wife Teresa and I just love this place,” Lynch said recently while standing near the garden of the Black House. “We have gone hiking many times, and there are winter activities in the woods out back.”

Thanks to Lynch’s vision, enthusiasm and love of history, many of the contents of John Black’s mansion will be preserved and inventoried for the first time. It’s enough to make the colonel, who died in 1856 at age 75, wish he could come back for a day, just to bask in all the glory.

And who knows. The little old lady holding the brown paper bag may be bearing a treasure.

“The ugliest thing in the house could end up being the most valuable item at the appraisal,” Croul said. “There’s always the excitement of discovery.”

Appraisal day will be held on Tuesday, Aug. 3, at Ellsworth High School from 10 a.m. to 4 p.m. Lectures will be from 11 a.m., 12 noon, 1 p.m. and 2 p.m. In addition, Donald Cresswell will lecture on “The prints, maps and other objects on paper” in the collection of the Colonel Black Mansion on Monday, Aug. 2 at 4:30 p.m. at the Ellsworth Public Library. Admission is $5.