LOS ANGELES – Frank Sinclair, founder of Sinclair Paint Co., a major regional manufacturer of architectural coatings in California, died June 3 in Los Angeles. He was 90.

Mr. Sinclair led the expansion of a depression-era storefront business into a multimillion-dollar corporation, exploiting California’s building boom by focusing his company’s manufacturing and marketing efforts on the demands of professional painting contractors and decorators.

Mr. Sinclair was born in 1910 in Massachusetts, but moved to Los Angeles as a young man and opened his first paint store in 1928, using $200 borrowed from his mother. He opened a second store in Hollywood in the 1930s, and the business expanded gradually until the mid-1940s, when Mr. Sinclair won a contract to provide all the paint for the construction of the new city of Lakewood, CA. At that time, the company began large-scale manufacturing operations at a plant in Los Angeles. A second plant was opened in 1956. Manufacturing was later consolidated at a new facility, and by the time Sinclair Paint Co. was acquired by ICI in the mid-1990s, the company operated the largest paint-manufacturing plant in Southern California, in addition to 60 stores in California, Arizona, Nevada and Hawaii. The company also sold its products in Asia through licensing agreements.

Mr. Sinclair was a believer in family and hard work, and was joined in the business by six brothers, a brother-in-law, his son Robert, and his son-in-law Richard Carlson. Robert Sinclair was president of the company after the business was sold to Insilco Corp. in the early 1970s, and Carlson was vice president of Sales. Individual family members specialized in certain aspects of the company’s operation, while Mr. Sinclair provided a vision and served as the driving force behind the company’s strategic direction. After the company was sold to Insilco, he remained chairman until his retirement in 1983.

A generous supporter of Los Angeles charities, Mr. Sinclair was a charter member of the Founders Circle of the Music Center in downtown Los Angeles. He was active in the Shriners and was a founding member of the Paint and Chemical group of the United Jewish Fund and of the Medallions Group of Cedars Sinai Hospital.

Mr. Sinclair is survived by his wife, Anne; two sons, Robert and Daniel; a daughter, Gail Carson; three grandchildren; a brother; and a sister.