Software fills in concave surfaces like they're filled with water

[burnwood123]

Hi everyone I've just started learning how to use 3d printers in general. My first part is a 30mm diameter disc with 1.5mm walls. It's concave like a bowl, and when I print, the software seems to fill in all concavities as if it's filling the bowl with water. Any ideas as to what settings I can change to get rid of this? Seems like I've tried everything and nothing works. Thanks!

[Mjolinor]

You need to provide more information like what you drew it in, what you sliced it in and what printer it is.

If possible post your file here so that people can look and see.

[Starlord]

I might be that your STL is not manifold. This would cause the splicer to do weird things.

[burnwood123]

Thanks Starlord. I think you are correct. My model was all surfaces. When I knit into a solid, the Makerbot slicer produces the correct preview. I will test today. Thanks!