Changing foreground/background colors in all frames

[Swidan, Firas]

Hi,

I am unable to set the default foreground and background colors in all emacs
frames. I have added

(set-background-color "black")
(set-foreground-color "white")

To my .emacs. This changes the setting in the first emacs frame.  However,
if I use 

C-x 5 f 

To open a new file in a new frame, the foreground/background settings in the
.emacs file do not seem to affect the look of the new frame.

Any ideas how to tackle this issue?

Many thanks and all the best,
Firas.