I've made the bottle object using the glass material and then made the contents slightly smaller with a graphic placed with the fill option on repeat. It looks about how I'd like it to in the design view, but when I render it, I don't know if the glass outer bottle object is reflecting the inner contents objects placed graphic or what. It appears as though the graphic of the inner/smaller content onject is on the outer/larger bottle object in the render.
Attached is a gif of a screenshot of the design view, the render with the content object turned off, and then with it turned on. I'd like it to look more similar to the desiign view how you can see the thickness of the glass bottle and then the content within, but I'm not sure how to make that happen in the render.
Try to change Translucencc properties of your glass material
I had tried those settings but playing with them more today, I think I have made it work. What I found to work is adjusting the Index of Refraction. On its own this didn't work as I had tried it before. I needed Index of Refraction to be less than 1 and it would only work if translucence was set to 99 or below. As I don't want the bottle to appear frosted, I am using 99 and it looks decent. It does diminish the feel of how glossy the bottle is slightly, but it is an improvement over what I had.
be careful with Index of Refraction because it needs a full rendor to show i.e, if you adjust it with only the preview rendor then the full effect will not show... also adding Refraction to any model will increase how much work your Cpu needs to do in order to rendor it and that means extra time and Ram
If there is any other way around this, I'm open to your input.
I'm not super satisfied with the index of Refraction solution. It's very much reducing the glossiness that I'm able to achieve. I've tried a bunch of settings and it oddly doesn't help until I reach exactly 1 or less. It's odd sometimes the slider lets me go down it .5, sometimes it goes to 1 as the minimum.
Try adding a background image of a table or outside bench instead of refraction... This will show up the glass by the way it distorts the image and looks more like real life
I'm making label mockups to go on print mechanicals and I need them to be clean. Also I have had to make e store product images which are required to be on a white background. I can see where the settings can be adjusted more easily where the glass shows up against the darker shadow behind but blends into the white higher up and it does seem that a colored background would make it easier, but often that's not an option.
May be changing environment lights or light angle can help to make it more clean? Did you try that? At the last end you can render Ps file and try to make corrections in Ps.