Read the Kodak information at the following site for safelights. http://www.kodak.com/global/en/consu.../k4Facts.shtml
I quote from Kodak's recommendation.
"The 'safest' color safelight filter for a particular material is not always the recommended one. For example, a red safelight filter often has less effect on photographic papers than the amber filter listed in the table. However, most workers find that they can judge print density or perform other functions better under an amber light. (So, although it is a slight compromise in protecting the paper from fogging, an amber filter improves working conditions.)"
I have used both and what Kodak says is true. With red illumination the human eye has trouble discerning small details.