Why They Call It The White House

Naming conventions
When construction was finished the porous sandstone walls were coated with a mixture of lime, rice glue, casein, and lead, giving the house its familiar color and name. The building was originally referred to variously as the "President's Palace," "Presidential Mansion," or "President's House." Dolley Madison called it the "President's Castle." The earliest evidence of the public calling it the "White House" was recorded in 1811 due to its white-painted stone exterior. The name "Executive Mansion" was used in official context until President Theodore Roosevelt established the formal name by having the de facto name "White House–Washington" engraved on the stationery in 1901. President Franklin Roosevelt changed his letterhead to "The White House" with the word "Washington" centered beneath. That convention remains today.

Go to the link below:

http://en.wikipedia.org/wiki/White_House