To the untutored eye little is different about “The Actor,” the Metropolitan  Museum of Art’s rare Rose Period Picasso,  other than that it is now safely behind plexiglass. It’s virtually impossible to  tell that on a January afternoon a woman taking an adult education class  accidentally fell into the canvas, causing a six-inch vertical tear along the  lower right-hand corner. 
 “The Actor” went back on the museum’s wall last week as curators started  installing “Picasso in the Metropolitan Museum of Art,” an exhibition that opens  next Tuesday (with previews for members through the weekend) and includes nearly  all of the institution’s collection of Picasso’s oeuvre: paintings, drawings,  sculptures, prints and ceramics. 
 Nobody was taking any chances. Three months of work had gone into getting the  105-year-old “Actor” as near to its original state as possible. “I felt strongly  that people would get very close to it,” said Lucy Belloli, a conservator at the  Met, “and it needed some protection.” 
 Painted when Picasso was only 23, it depicts a tall, gaunt actor dressed in a  commedia dell’arte costume leaning out across the footlights of a stage. Faintly  visible in the right-hand corner are the prompter’s hands. (The tear was below  and to the right of the hands.) 
 Gary Tinterow, chairman of the museum’s department of 19th-century, modern  and contemporary art, recalled what the painting looked like right after the  accident. “We saw the big, coarse threads that looked sort of like a nasty jute  rug,” he said in an interview recently. “The question was how to get Humpty  Dumpty back together again.” 
 Listening to Ms. Belloli describe restoring “The Actor” is like hearing an  emergency-room doctor discuss the treatment of a patient who has been in a  horrific car accident. “This was a traumatic event in the life of these  materials,” she said, standing in a museum gallery last week and describing how  right after “it” happened the painting was whisked to the museum’s conservation  studio. 
 She said that although there are far more materials to choose from than ever  before, the basic methods she used to restore “The Actor” were decades old. 
 The first step was to photograph the damaged painting, to get a complete  visual record of it. Then she gingerly secured the loose paint flakes around the  rip with a liquid adhesive. “I didn’t want to lose any of it,” she said. To  protect the edges of the tear, tiny strips of paper and rabbit-skin glue were  applied on both the front and back of the canvas, so it “looked like a series of  tiny Band-Aids,” she said. 
 The conservators had to act quickly because canvases, like people, “have a  memory,” she explained. That is, the torn portion of the canvas had to be gently  coaxed back to its flat state, otherwise it would have a tendency to return to  the distortion left by the accident. 
 Making the job particularly complex, Ms. Belloli had more to worry about than  just the image of “The Actor.” There was a painting on the back of the canvas,  and that had to be considered too. 
 For years only a few scholars knew that this second painting existed, and  they debated among themselves what it could be. Was it a discarded work by  Picasso or, as John Richardson, Picasso’s biographer, hoped, the missing 1901  painting titled “Virgin With Golden Hair”? Hubert von Sonnenburg, a former  conservator at the Met, hypothesized that perhaps it was a stage decoration by  someone else because the canvas was thick, not the fine artist’s weave a painter  would normally use. 
 “The canvas and composition do suggest a work intended as a decoration,” Mr.  Tinterow said. “And the colors were particularly theatrical and vivid.” 
 “The Actor,” made in the winter of 1904-5, dates from a period in Picasso’s  life when he was particularly poor, and he often employed whatever canvases or  materials he could get his hands on even if they had already been used. He may  have tried to obliterate the original composition by painting over it, but  X-rays taken at the museum revealed a landscape with stones in a rippled body of  water, rocky palisades and a large figure that might have been a female nude,  although Mr. Tinterow said it was impossible to determine that with certainty.  
 The bold, swirling brushstrokes and palette were definitely not Picasso’s.  Rather the colors — gold, mauve and cerulean blue — were in keeping with the  work of Symbolist painters in Barcelona who appear in caricatures by Picasso.  “It could have been done by Isidre Nonell, one of the Symbolist painters who had  a studio in Paris and was known to have given Picasso materials in 1901,” Mr.  Tinterow said. 
 Whoever the artist was, the X-rays showed that the landscape was painted  horizontally, and that Picasso rotated the canvas for the vertical composition  of “The Actor.” 
 Restoration involved a slow and careful realignment of the painting, and that  meant time. So for six weeks “The Actor” lay face down, with varying weights on  it to counteract the “memory” of the damage. First, Ms. Belloli said, she placed  small silk sand bags that she made herself on the affected area; then slightly  heavier ones, the kind seamstresses use to hold a pattern in place; and  gradually heavier and heavier weights, stopping at one pound. Once the canvas  seemed stabilized, she placed a clear Mylar patch on the back. “We didn’t want  to hide any part of the other painting,” Ms. Belloli said. 
 Some careful retouching was ultimately required, especially where paint had  flecked off around the tear. Ms. Belloli used three layers: a synthetic gesso  over which she applied gouache and finally a pigment-and-synthetic resin that  resembles the original oil paint. 
 “As it ages it will inevitably look different,” she said of her handiwork.  And unlike the early-20th-century oils, the pigment-and-synthetic resin can be  easily removed and freshly retouched when necessary. “Everything changes in  time,” Ms. Belloli said. “And this way it will be easy to fix.”