I need to get a true gold color on a wedding cake that is edible. I tried using gold glaze but it leaves brush marks. I am looking for a very clean look. Can anyone suggest anything. 

sure -- gold foil will do it -- it is edible and expensive -- if you find a good deal on it it is not real gold nor edible -- there's a bit of a leaning curve because it will blow away by just your breath --

just turning the leaves in the booklet it comes in  can cause it to slide on itself and dissolve -- but you learn quick enough so be sure to purchase enough to cover the cake and a few extras 

http://www.amazon.com/Edible-Gold-25-3-3-square-sheets/dp/B0006GSQYK

I use the wilton spray.  I use them for ailver and gold.  The gold i found if i apray them and then add dust it comes out nice.  

Thank you everyone!!!!!

Also, if you can color in advance whatever it is that you want to be gold--buttercream, fondant, gum paste, etc.--it will help a lot.  I usually find that a brownish yellow with the gold dust/paint on it looks very rich.  If you use a light yellow or a dark brown, you'll get different results.  It's a good idea to do some tests before you commit because what's under the gold effects the final result a lot.

AS maybenot suggested, dying whatever medium beforehand some shade of yellow provides a great base for the gold.

I use the gold Wilton spray lightly and then use chef rubber (brand) gold and dust the whole thing. That way you have no brush strokes and a nice sparkly gold.