Quick question about Mod Podge (and maybe Stormshield?)

Posted in Custom Workstation

Hello! I'm just finishing up my first custom figure, and I had a quick question about using Mod Podge to seal my paint job. I did a test run on a spare fodder piece and was pleasantly surprised with the matte finish. However, looking closely, I noticed some brush-marks where I had painted the MP on. I assume it's because I put the stuff on too thick? Are you able/are you supposed to add a drop or two of water to Mod Podge before using it, same as with paints? Any tips or advice would be appreciated.

Also, I have a pot of Citadel Stormshield from my Warhammer painting stuff. Does anyone have any experience using that to seal a custom Marvel Legends figure?
Thanks!