Decoupage always works best when the paper is used in smaller pieces. The reason it's bubbling is because you have air bubbles that are trapped underneath the paper. Wrapping paper can be used but it takes a little more effort due to it's weight and even more effort if it has a glossy surface. You need to be VERY generous with your glue regardless of what kind you use.
I love decoupage, here are a few tips.
- If using a non-porous surface (metal, glass, etc.), prepare your surface by sanding it and wiping it clean with a cloth.
- If basecoating with paint or stain, let it dry completely before continuing.
- Apply the decoupage medium generously to both the surface and to the BACK of the print to ensure complete adhesion to the surface. After you lay the paper down on the surface and it's still wet underneath, roll over it with a brayer to flatten it and remove any existing air bubbles. An empty jar works well if you don't have a brayer. If any small bubbles remain, pop them with a straight pin and flatten with either your brayer or a wet finger.
-Lat this dry completely BEFORE you continue.
- Now start applying your topcoat letting each coat of decoupage sealer dry completely before applying the next.
*** Personally I don't care for Mod Podge. It is very temperamental to humidity changes and has a tendency to go milky and opaque. If you live in an area where there is high humidity it can also take forever and a day to dry. And it doesn't dry to the hard finish I prefer. The two products I use and like are Aleene's Instant Decoupage Finishes and Plaid's 'other' decoupage finish, Royal Coat. They both dry to a good hard acrylic finish like a varnish should.
Most decoupage projects I read about on message boards that have 'gone wrong' were done with Mod Podge.
I hope you found any of this information useful.