Preview render doesn't match final render

Hi all!

I understand a preview render will be a rough copy of a final render and not the end result, but I think the difference is really off.

The top middle panel is viewport preview of material on the pen’s middle section. The bottom left panel is a final render. The preview and final render settings appear to be the same. The pen’s middle section appears to be more transparent in the final render compared to the preview render. This is making it hard to get the material just right. Any reason for this?

Thanks for any help,

Edit: Nevermind, I found the problem. The part had a solidify modifier that was disabled for rendering, but enabled in the view port.

I would also suggest that instead of using color on your glass material, you use a volume absorption with the color you want to pronounce the thickness of your object.