San Francisco — Many successful companies are reporting new ways to crack new markets - sometimes just by expanding their standard and staple products. Sears, Roebuck recently announced it will open six free-standing paint and hardware stores on a test basis in 1983. The first will be located at Buffalo Grove, Ill., a Chicago suburb, with another to follow in the Chicago metropolitan area. Two more of the 2,600-square-foot units will be opened in the greater Los Angeles area, and another two will follow these in the New York metropolitan area.
''The free-standing, dominant-product store appears to have real merit in highly competitive areas,'' said one West Coast Sears spokesman. ''Our preliminary studies indicate the prime consumer preference for shopping these days is convenience of location. And this factor, we believe, we can accommodate - with tight merchandising of related lines where shopping traffic is at a maximum.''
Sears has gained some recent experience with separate, related-product units in its free-standing business-equipment centers. These too have been located in important high-customer-traffic areas. Their success in exposing many brands of computers and accessories could lead to further expansion.
In opening the proposed new test stores, Sears is banking on two of its strongest veteran merchandising lines - paint and hardware - to add volume from outside its multi-line retail and catalog-sales stores. The paint and hardware stores will carry need-related accessories - ladders, sprayers, wall coverings, sealers, portable electric tools, and a long line of handy hardware items.
Mattel Inc., the California toy and electronic manufacturer, has a change-in-marketing idea, too. It recently formed a new subsidiary, Mattel Direct Marketing Inc., to sell its products to the public over the phone, through direct mail, and possibly door to door. Company executives said they expect the plan to begin operation within two months. At present most of the company's goods are sold only through conventional retail outlets.
And in what used to be called simply the music business, there's a branching out, too. According to officials of the Record Industry Association of America, sales of prerecorded audio-cassettes are booming - and these may eclipse the national sales of record albums in 1983.
Responsible for the increased cassette demand has been improved quality of prerecorded tapes. Record companies have been bringing these out to combat the sales of the blank-tape cassettes said to have glass-shattering fidelity. But many marketers of taped musical performances believe product improvement alone is not enough to reach the full potential of cassette sales.
The main in-store problem of selling retail cassettes has been their vulnerability to loss and theft. Because they are small and easily concealed, most stores up to now kept stocks locked in cases or lined up behind counters manned by sales clerks.
''This goes against all the principles of mass merchandising,'' said one retail-store operator. ''The theory for a long time has been 'Let the customer see, pick up, and touch the merchandise.' ''
So now there's a new idea being introduced to help get more cassettes into customers' hands - and consequently get more dollars in the till. MCA Inc. is experimenting with a 12-inch enclosure that attaches cassettes to a jacket similar to those enclosing record albums. The new packaged display comes with performer and musical-score information formerly included only with record albums. And the merchandise is set up to be moved out of locked cases and from behind counters so that, as one sales clerk said, ''Finally - finally - everybody can get close enough to really read the labels.''