Is Mod Podge waterproof? Can it work to seal decals?

You can get a waterproof Mod Podge- they have them at most craft stores, like Mihceals

I would recommend an outdoor epoxy that dries clear as it was noted in an article Mod Podge will peel off.

My husband is a builder of plastic model kits, and I think he'd avoid using mod podge, because it's too thick. You'll want a very thin adhesive, one that doesn't add the slightest bit of ridges to your decals.

and you can google this! you'll see it shouldn't be used outdoors

Modge Podge is basically watered down Elmer's glue. It isn't waterproof. Google homemade Modge Podge the next time you need some. It's a lot cheaper. They sell clear sealants at craft stores you can brush on.

You can buy Exterior Mod Podge!

Yes they make outdoor Modge Podge.

They have different formulas. Check them out here:

https://modpodgerocksblog.com/every-single-mod-podge-formula-explained/