The Corby mansion in north Bethesda, slated to become in arts center for Montgomery County by 1982, has been selected as the site of its Decorators' Show by the women's committee of the National Symphony Orchestra.

The NSO women's committee, which for nine years has been raising funds to benefit the orchestra, will occupy the mansion on Aug. 15, according to committee chairman Carol O'Colmain. Through sale of tickets and boutique items at its Decorators' Show houses, the committee annually raises more than $200,000.

For the October show, both well-known and novice interior decorators will redecorate each room in the three-story mansion.

County officials say Montgomery will get up to $200,000 worth of donated decorating and design work throughout the mansion's interior. In addition, the county expects to raise $250,000 from two events scheduled during the show. A wine-and-cheese party will be held Oct. 11, and a tea dance Oct. 18.

Funds appropriated by Montgomery County will be used to carry out limited remodeling of the mansion before the October opening of the show. (A preview of the show, which runs through Nov. 16, is scheduled for Oct. 2.) The County Council last month approved an emergency appropriation of $118,500 for the purpose.

Known informally in Montgomery County as the Corby mansion -- the building and the 11 acres on which it stands once belonged to the bakers of Mother Corby's Bread -- the mansion's name has been changed to Strathmore Hall by county authorities to avoid confusion with the Corby Mansion at Chevy Chase Circle. The new name comes from a road that borders one side of the property.

At the close of the Decorators' Show, the Montgomery County Department of Recreation will take over the site. The county arts council will move its offices to four rooms in the mansion at the end of November. The projected date for the opening of the arts center is July 1, 1982.

The recently approved appropriation is the first portion of an estimated $685,000 required to develop the mansion for public use. Funds are needed to meet architectural and engineering fees, carry out renovations to the property's entrance and roadway, expand the number of parking spaces to 100, repair and paint the building; ensure accessibility for the handicapped, remodel a warming kitchen, and install sprinkler, modern heating and air conditioning systems.

When the county two years ago purchased the mansion and the property surrounding it for $1.3 million, plans for development included an outdoor amphitheater and a 500-seat indoor theater adjacent to the building. The plans are still intact, but the arts center planners must raise funds on their own and will not be able to count on county funding for construction, according to the arts section supervisor of the Department of Recreation, Eliot Pfanstiehl.

Ten rooms in the future arts center will serve as "art-on-the-walls galleries, 75-seat chamber music or small recital halls and the place will be perfect for string quartets," said Pfanstiehl.

Pfanstiehl, son of Metro spokesman Cody Pfanstiehl, is confident Strathmore Hall will be a "lighthouse for Montgomery County arts groups. We have many groups in the county, but they seem to be too well hidden and Strathmore will better expose them." He adds that "the times, economically and politically, are right for this new partnership of public and private sectors combining efforts to give the arts center and the county, in general, a touch of class."

On one of the numberous tours Pfanstiehl leads, he points to cherubs carved into a stone fireplace mantle: "See, the cherubs are painting and performing. This place was destined to be an arts center."