Precautions in use
Pencils・colored pencils ：What is the time limitation of pencils
The barrel and the lead of pencils do not get rotten, but pencil’s condition gets worse in extremely dry or humid environment. The better the storage state, the more semi-permanently available. The oldest pencil in Japan was made about 400 years ago in Kunozan, but it is still able to write.
However, in terms of color concentration, oil that has been soaked in pencils might become thinner due to long-term storage.