Subsurf is creating weird reflections

Hi guys, im having some issues with the subsurf modifier. As soon as I apply it… i can see some weird reflections on my glass surface. Im not sure where these are coming from.

The first image is with the subsurf on… you can see these weird arcs above the label… in the last picture thesre are gone, which is what i want. However… I want the top of the jar to be as the first picture… so just clear glass without the blackness of the second picture…

not sure what im doing wrong… thanks in advance

Do you use Subsurf on the “content” as well?
If not, those effects might very well be artefacts created by gaps/intersections between the glass and the other surface because of the Subsurf.

If you want a more in depth answer, please supply an example .blend file.

looks like bad topology, but without some wires or a blend, its hard to know.

try making the green liquid inside a little bit larger so that it overlaps the inside of the glass, it may be that when subsurf is enabled it shrinks it down a little and there is a gap between the liquid and the glass which is bad.

Just had a thought, are you using a blender cylinder ? If so remake the cap by extruding inward properly. Those cylinder primitives are a disgrace and should be changed.
This must be it, have a look:

Turns out it was caused by the space between the powder and the glass… WHen I deleted that space…thse reflections were gone…
thanks guys!