The glue you choose to use for your collage project will depend on what type of items you are using. In some instances, you may even use a couple different kinds of glue for a single collage. You might, for example, need a good spreadable adhesive for paper and a heavier duty one for the objects that go on top of that background.
Many crafters find that having a variety of glues on hand is the best approach. The good news is that there is a glue for everything! Once you get the appropriate one for your project, you can start making your masterpiece.
If you are strictly using paper to make your collage, you might want to use a simple glue stick. It can easily be found at craft stores as well as just about any other store you can think of. Glue sticks are inexpensive, clean and easy to use, and generally a good all-around glue. It's also the best choice when children are working on a collage.
The main problem you might run into with a glue stick is that it can get thick and bumpy and cause your paper not to lay perfectly flat. You may also find times when it's hard to get to the edges of your paper.
A favorite glue for many paper crafters and scrapbookers is Beacon's Zip Dry glue. It dries fast and clear and claims to never wrinkle or warp paper. If you ask anyone who has had experience with this adhesive, they'll probably tell you that all of this is true.
Zip Dry does have an odor that can bother some people who are sensitive to that. It's also more expensive than glue sticks or the average craft glue. However, a little bit does go a long way and if you work with paper often, it's definitely worth having in your craft kit.
Decoupage mediums are an all-in-one gluing and sealing product. You can use it to glue down your items and then spread it over the entire finished project for a nice seal that will protect it for years. It works great for both paper and fabric and is easy to apply with a foam or bristle brush.
Many professional artists who work in collage prefer to use an artist-grade acrylic medium, such as those made by Golden, a leader in artist paints. It's not much different than decoupage, but it can offer some benefits if you find that you really like collage.
The biggest benefit of acrylic mediums over a decoupage medium is that the acrylics are thinner. There's no need to water these down to get a thin, workable paste or sealer when needed. Plus, you can often find the same quality of medium in both gloss and matte finishes. Since it is made for artists, acrylic mediums will cost more, but a bottle will last a long time.
If you are making a collage with heavier items, such as buttons, beads, or found objects, you will want to use a thicker craft glue. There are many great options available at any craft store and it's worth the time and money to experiment and find out which you like working with best.
In general, craft glues would not be the best choice when working with paper. It can cause the paper to warp and cause unsightly bubbles and creases. Instead, keep this around for three-dimensional collage work that needs a sturdy base.
For really heavy objects, craft glue may not hold. In that case, you might want to consider a strong epoxy. Just make sure it's not visible because most don't age well and can turn colors over time.