White cards or 18% grey cards for white balance for HMC40..and why?

[JoeJITSU]

Just got my 18% grey card that I can use for my wifes HMC40 and my 7D. Can someone explain to me which would be best to use and why? Thank you

 

[Felipe Henao]

I use the gray side, because the white balance is much more accurate than with white, Why ? good question

 

[Garion]

Totally agree, if i use my white card the colour balance is too "sterile/cool". When i use a grey card the colour balance is spot on wierd.