Orange Susan VerBurg was a teenager at Tustin High School when her father, Merle, started his own stucco-manufacturing plant in Orange.

She never aspired to take over the family business, instead majoring in art in college and owning several businesses in Oregon. Only when Merle became ill in 1991 did Susan return to help with Merlex Stucco Inc.

After he died two years later, she bought the company, the third-largest stucco manufacturer in Southern California, from his estate.

Even though sales have doubled to $8 million, and the staff has increased 135 percent to 40 employees under Susan VerBurg's leadership, she credits the company's foundation, reputation and work ethic to her father.

They are why Merlex is still around to celebrate its 40th birthday with a barbecue for customers, employees and friends Friday, she says.

A child of the Depression and a World War II prisoner of war, Merle VerBurg was thrifty, hard-working and a stickler for quality products and customer service.

''He was a driven man. He'd jump up on scaffolding and tell workmen exactly what he wanted,'' Susan VerBurg remembers. ''My dad called into work on the day he died and said he would be in the office the next day.''

After working for his own father in a sand business in San Diego and working his way up to vice president at another stucco company, Merle VerBurg invested all he had, $5,000, and borrowed $20,000 from family and friends to start Merlex.

''No one has a better reputation for quality and service,'' says Bill Moeder, general manager of Oxnard Building Materials in Corona.

Ron Wooster of Acoustical Material Supply in Anaheim agrees. ''Their stucco is a good, workable product. I sell all the brands, and ... residential builders and architects specify Merlex because it has the different colors they like, fast turnaround and service.''

Merlex struggled in the early years, but Merle VerBurg paid back the initial debt and grew the company slowly because he didn't want to borrow money.

''Long before the environmental movement, Merle would reclaim every bit of (stucco) dust because that was money to him,'' Susan VerBurg says.

When Merle died, ''I'd hear rumors that the company was going under,'' she says, acknowledging that sales dropped and equipment wasn't fixed in the year before his death.

When she took over, ''I didn't know anything about the company. But I could admit it.''

Unlike her father's solo style, Susan VerBurg insists on building a strong team.

Many of Merlex's employees remained loyal and helped assess what needed to be done, not just to save the company but to grow it.

The plant on Orange-Olive Road had to be restored. Then it needed to diversify.

''We had one product, stucco, sold in one county, Orange County, to one segment, residential builders,'' she says.

Merlex added related products, including masonry, waterproofing, coatings and architectural foam. Its sales staff started pursuing commercial projects, such as the St. Regis Monarch Beach Resort & Spa in Dana Point, Universal Studios City Walk in Los Angeles and the Hollywood Bowl remodeling.

It has started selling in Utah, Nevada, Canada, South Korea and other markets.

To further diversify, Susan VerBurg has launched a second company, Vero, to distribute Rialto high-end Italian plaster finishes.

The addition contributed to staff problems and the departure of the company president and two salespeople.

''We've just come through a difficult year,'' VerBurg says. ''I expect my team to be open to new ideas. We're a profit center, but we're also a people center.''

General Manager Nick Brown says, ''The team had started underperforming and stopped supporting Susan's vision for Vero.''

He left National Gypsum in Long Beach to join Merlex in 2002 ''because this company has a tremendous reputation, and it's an opportunity to have a bigger role in a smaller company.''

The 40th-birthday party will celebrate Merlex's past and its future. It no doubt will end as all staff dinners now do. Someone will rise and say,