Most actors would probably have refused to wear such difficult makeup but Chaney (whose real first name was Creghton) had no choice, he was desperate to make it in the film business.
  While he was alive Lon Chaney Sr. had fought Creightons' attempts to become an actor.  He even forced his son out of Hollywood High and into a plumbing school when he asked to take acting lessons.  As Chaney Sr.s' career soared to its heights in the late 1920's Chaney Jr. was working as a boilermaker.
  Lon Chaney Sr. died of throat cancer in 1930.  Creighton Chaney signed with RKO studios two years later.  After moving from bitpart to bitpart for more        
than two years, he reluctantly changed his name to Lon Chaney Jr. to cash in on his fathers fame.  "They had to starve me to make me take his name" he was once quoted..
  Finally, in 1939, only days after his car and f urniture were reposessed by a furniture company, Chaney scored a hit in a stage version of "Of Mice And Men"  That led to a starring role in the movie version and in 1940, a contract with Universal.
  The studio had modest hopes for "The Wolf Man".  They scheduled its release for December 11, 1941, right before Christmas.  But on December 7, Japan bombed Pearl Harbor and the United States entered  World War II.  Universal was sure the movie would become a box office disaster.  After all, who was going to take time out for a movie when they were going to war?
  To their surprise, it was a hit!  The film played to packed movie houses all over the country and was the studio's  biggest moneymaker of the season.  It established the Wolfman as an important movie monster, along with Dracula and Frankenstein.  It almost singlehandedly made werewolves a part of the popular culture and it turned Lon Chaney Jr. into one of the best known actors in the country.
World War II probably had more to do with making "The Wolf Man" a hit more than any other factor.  What Universal had failed to realize was that the war fueled a need for the kind of escape that horror films provided.  Inside a darkened theatre moviegoes could forget their troubles for a  while as they watched ordinary mortals triumph over seemingly insurmountable evil.  As David Skal writes in "The Monster Show: A Cultural History Of Horror":
[Talbots" four-film quest to put to rest his wolf-self is, in a strange way, an unconscious parable of the war effort.  The Wolf Man's crusade for eternal peace and his frustrated attempts to control irrational, violent, European orces....The Wolf Man's saga was the most consistant and sustained monster myth of the war, beginning
with the first year of America's
direct involvement in the war
and finishing up just in time
for Hiroshima.]
  The hardest scene to shoot
was the final "metamorphosis"
scene in which Chaney turns
from a werewolf to a human
as he dies.  Chaney describes
the process:
The way we did the transformation
was that I came in at 2:00 a.m.
When I hit the position, they
would take little nails and drive them through the skin at the edge of my fingers on both hands so that I wouldn't move them anymore.  While I was in this position, they would take the camera and weigh it down with one ton so that it wouldn't move when people walked. They had targets for my eyes.  Then they would shoot five or ten frames of film in the camera.  They'd take the film out and send it to the lab.  While it was there, the make-up man would come and take the whole thing off my face and put on a new one.  I'm still immobile.  When the film came back from the lab, they'd put it back in the camera and then they'd check me.  They would say "Your eyes have moved a little bit, move them to the right..."  They they would roll it again and shoot another 10 frames.  Well, we did 21 changes of makeup and it took twenty two hours.  I won't discuss about the bathroom.....
  For the rest of the cast and crew, the worst part of filming The Wolf Man was breathing the special effects fog that was used in the outdoor scenes.  "The kind of fog they used in those days was nothing like the kind we have today," cameraman Phil Lathrop remembers.  "It was greasy stuff made with mineral oil.  We worked in it for weeks and the entire cast and crew had sore eyes and intestinal trouble the entire time.  Besides that, we were all shivering with cold because it was necessary to keep the temperature below 50 degrees when using the fog."  Female lead Evelyn Ankers fainted on the set after inhailing too much fog during a chase sequence.