Solarplate: exposure for aquatint vs exposure for image

Hi everyone this is my first post on this site!
I am a fine arts student in NZ. I have been experimenting with photopolymer techniques, the most successful one being Solarplate. I am refining my technique with it currently and wonder if anyone has advice on the time ratio between aquatint ( I am using Weldons one) and image??
I made a very detailed plate today with equal exposure time for aquatint and image. The only problem was that the image was tonally flat, no rich shadow.
I imagine that if I change the ratio, I will get better contrast. I have mainly heard of the aquatint exposure being shorter than the image exposure, but tonight read something to the contrary.
Any advice?
Thanks

If you have no shadow depth, you probably need to drop the screen exposure relative to the image exposure. I use Toyobo KM73 plates and the ratio usually runs about 1 : 1.2 (screen : image)

Thanks for that! I will give it a go today. I am working with sunlight and the skies are a stormy grey- wish me luck!