Refract material gives me black gaps

[gagui]

Hello.

I'm fighting with a problem I can't find a solution.
I have the liquid of a bottle wich is solid and has a water material.
I found that it gives me some black lines and firstly I though that it was some refracted distortions of the environment but no.
Here is a screen capture where the liquid is isolated and surronded by a big red sphere to try to determine where those blacks are coming:



But they keep appearing so I increased the max depth of refract rays in the water material but nothing change.
Rising this max depth should make that more refracted levels are drawn.

Could anyone tell me where those blacks are coming or how to avoid them?

I remember in the past vraymaterial has an exit color parameter. Could be that a solution?

PS. one thing I gorgot to mention is that there's no light in the scene. The red spehere is self iluminated but with no GI contribution.

[kosso_olli]

Set Max depth for reflection and refraction to a value of 32 and try if the black areas are getting smaller.