What is "Black Back" Vinyl?

Well, at the risk of sounding obvious . . . it’s vinyl with a black backing to it as opposed to the traditional white backing (since most printed vinyl starts out as white).

Click below for the non smart-alec answer.

The advantage of black back vinyl is that is acts as a blockout to anything that might be behind your vinyl.  In the case of a billboard, the opposite side of the board or the structure of the billboard itself can cause “ghosting” or cast shadows on YOUR billboard.  At certain times during the day this is quite obvious and unattractive.  Check for this as you drive around town, especially in the morning and evening when the sun is lower in the sky.  You will almost certainly see certain billboards that are not using black back vinyl where you can see the shadow cast by the structure.  Black back vinyl prevents this from happening.