When it comes to correcting papers and grading tests, purple is emerging as the new red.

"If you see a whole paper of red, it looks pretty frightening," said Sharon Carlson, a health and physical education teacher at John F. Kennedy Middle School in Northampton. "Purple stands out, but it doesn't look as scary as red."

That's the cue pen makers and office supply superstores say they have gotten from teachers as the $15 billion back-to-school retail season kicks off. They say focus groups and conversations with teachers have led them to conclude that a growing number of the nation's educators are switching to purple, a color they perceive as "friendlier" than red.

As a result, Paper Mate introduced purple to its assortment of blue, red, and green X-Tend pens and increased distribution of existing purple pens this school year. Barry Calpino, Paper Mate's vice president and general manager, estimated that the Bellwood, Ill., company boosted production of purple pens by at least 10 percent. He said purple will now be a standard color in all its new product lines.

Office superstores such as Staples and OfficeMax also are making a splash with purple pens, stocking more of them, adding purple to multicolor packs, and selling all-purple packs. By comparison, Staples did not stock any exclusively purple pen packs last year and it hardly had any purple pens in its stores two years ago, said Robert George, the Framingham chain's senior vice president of general merchandise. Now, he said, sales of purple pens are growing at a faster clip than pen sales overall.

A mix of red and blue, the color purple embodies red's sense of authority but also blue's association with serenity, making it a less negative and more constructive color for correcting student papers, color psychologists said. Purple calls attention to itself without being too aggressive. And because the color is linked to creativity and royalty, it is also more encouraging to students.

"The concept of purple as a replacement for red is a pretty good idea," said Leatrice Eiseman, director of the Pantone Color Institute in Carlstadt, N.J., and author of five books on color. "You soften the blow of red. Red is a bit over-the-top in its aggression."

For office supply stores, color and fashion trends spell opportunity and risk. The trends allow them to freshen up staid old categories such as pens and markers, fueling sales. But getting a trend wrong -- betting on purple pens when teachers and students are buying green, for example -- can cost them sales during a critical retail period.

Red's legacy as the color used in correcting papers and marking mistakes goes back to the 1700s, the era of the quill pen. In those days, red ink was used by clerks and accountants to correct ledgers. From there, it found its way into teachers' hands.

But two or three decades ago, an anti-red sentiment began surfacing among teachers. Since then, no one color had emerged as red's replacement.

Is purple here to stay?

"I do not use red," said Robin Slipakoff, who teaches second and third grades at Mirror Lake Elementary School in Plantation, Fla. "Red has a negative connotation, and we want to promote self-confidence. I like purple. I use purple a lot."

Sheila Hanley, who teaches reading and writing to first- and second-graders at John F. Kennedy Elementary School in Randolph, said: "Red is definitely a no-no. But I don't know if purple is in."

Hanley said a growing contingent of her colleagues is using purple. They prefer it to green and yellow because it provides more contrast to the black or blue ink students are asked to write in. And they prefer it to orange, which they think is too similar to red.

But aside from avoiding red, Hanley said she is not sure color matters much. At times, she uses sticky notes rather than writing on a child's paper. What's important, she said, is to focus on how an assignment can be improved rather than on what is wrong with it, she said.

Ruslan Nedoruban, who is entering seventh grade at his Belmont school, said red markings on his papers make him feel "uncomfortable."

His mother, Victoria Nedoruban, who is taking classes to improve her English, said she thinks papers should be corrected in red.

"I hate red," she said. "But because I hate it, I want to work harder to make sure there isn't any red on my papers."

Red has other defenders. California high-school teacher Carol Jago, who has been working with students for more than 30 years, said she has no plans to stop using red. She said her students do not seem psychologically scarred by how she wields her pen. And if her students are mixing up "their," "there," and "they're," she wants to shock them into fixing the mistake.

"We need to be honest and forthright with students," Jago said. "Red is honest, direct, and to the point. I'm sending the message, 'I care about you enough to care how you present yourself to the outside world.' "