Deborah Turner recalls the first time she gave a beauty school customer a bleach job. "I put the toner on -- just like you're supposed to -- and all of a sudden it started turning purple."

Joan Sheingold still shudders when she remembers the first time she worked on a patient in her dental school clinic. "I was so scard I couldn't sleep for two nights," she said.

Both survived their ordeals, as did the people on whom they were working.

By the time Turner, 22, completes her beautician's course, she should know all about bleaches, not to mention hairstyling, permanents and hair straightening; and Sheingold, 28, will be able to fill a cavity, pull a tooth and prepare a set of dentures when she is graduated from dental school.

They're able to get pre-job training through programs that allow students to provide professional services under the supervision of licensed instructors. In turn, their customers can obtain the services at half the cost of going to a full-fledged professional.

"Sometimes they're just a little slower," said a 40-year-old office worker sitting under a dryer at Selan's Beauty School, where Turner is a student. "But I've gone to beauty salons where it's taken the same amount of time.

Hairstyling and dentistry are just two of the low-cost services performed by students under supervision. It's now possible to be treated by students from head to toe; and even after death.

In Chicago, for example, also operating or planned are programs at the Illinois School of Professional Psychology, the Worsham College of Mortuary Science, the Illinois College of Pediatric Medicine and the Illinois College of Optometry.

The various clinics draw old and young alike. Many of the customers of patients couldn't afford the full fee charged by licensed professioinals, although many of them could. "You'd be surprised how many mink coats walk in here," said Paul Selan, who runs the beauticians' school.

Proponents of the student-run clinics insist that their service is just as good as that provided by professionals, and sometimes even better. "We have specialists in six or seven areas," said Dr. Derrald Taylor, chairman of the patient-care division at the optometry school and director of its clinic. "A private practitioner by himself would be hard-pressed to be a specialist in all these areas."

Selan said, "We do a lot of corrective work from the shops. I've seen them come out of well-trained shops where they're really been butchered."

Virtually all of the students, whether would-be beauticians or dentists, train on mannequins before they tackle people. No matter how many hours they've put in in the classroom or laboratory, the transition still proves startling.

"It's whole different feeling," said James Wasilewski, a third-year dental student at the University of Illinois Medical Center campus. For starters, in the clinic, "The patient is moving target. In the classroom, everything is sitting still."