You need to edit your gradient that you are using for the mask. If you use a default linear gradient it is 100% on on end 0% on the other. Go to the gradient palette and slide black gradient slider over to about 90%. Another method you may like the results is switching the color of the black gradietn swatch to CMYK, and adding 50% or more cyan.
You will want to do some test prints if this is going to print, as a 5% dot may hold up differetnly on differetn pritning presses/calibrations. If you are doing video, taht yuor final results will be easier to judge directly on screen.