How to Seal Cardboard for Painting

If you’re painting something made of cardboard, it’s essential to seal the surface before beginning your project. Of course, if your piece will be sitting on a shelf or table, then sealing isn’t necessary because the sealant will peel off over time. But if you intend for this piece to be handled frequently, like in an office setting where people are constantly shuffling papers around it, it’s best to apply at least two coats of sealant.  

The first coat should go on as soon as possible after cutting out the pieces and before assembly (if applicable). Apply the second coat right before assembly so that it has plenty of time to dry without getting smudged by touch-ups with paintbrush bristles during construction. After assembling the piece, let it dry for at least four hours before handling. Read on to know more information about how to seal cardboard for painting.

How to Seal Cardboard for Painting

10 Ways on How to Seal Cardboard for Painting:

1. Use Mod Podge:

Mod Podge is a high-quality glue that’s popular among crafters. It comes in matte, glossy, or satin finishes and can be easily applied with a sponge brush to seal cardboard for painting.

2. Use Gesso:

Gesso is great for sealing cardboard or wood before painting. It’s a compound of casein, acrylic, and titanium dioxide that creates an even surface for your work to sit on top of. Gotta Be Mobile highly recommends using gesso to seal cardboard, whether you’re preparing the board for a painting project or just trying to keep a painting from moving.

3. Use Varnish:

Varnish is another excellent product for sealing cardboard, and it comes in several finishes that work well when preparing your board to be painted on. You can also layer additional coats of varnish to produce a paintable surface and create the perfect base for your art.

4. Use Spackle:

Spackle is an easy material to use when sealing cardboard because it spreads easily across the board surface and dries quickly, leaving you with a nice finish that’s primed for painting. In addition to priming cardboard, spackle can be used on wood and metal surfaces to prepare them for painting.

5. Use Gesso Primer:

Gesso primer combines gesso and acrylic paint that works well for sealing porous surfaces like cardboard, so your final product has something solid to sit on while you paint. You can apply it with a brush or roller, and you’ll find that the primer is water-resistant and paint-ready once it’s dry.

Use Gesso Primer

6. Use Latex Paint:

Latex paints are very inexpensive and work great as coatings to seal cardboard for painting projects. In addition to being incredibly easy on the wallet, they’re also straightforward to work with; grab a paint roller, and you’ll be well on your way to priming your surface.

7. Use Fabric Paint:

Fabric paints are another fantastic option for sealing cardboard surfaces. They usually come in small bottles, so you can easily apply them using a paintbrush, and they dry on a flat, smooth surface. Again, you can paint more than one coat to ensure your project has a perfect base.

8. Apply Spray Mount:

Spray mount is an adhesive made for adhering paper to surfaces like cardboard, but it can be used to seal the surface of your cardboard for painting. The adhesive spreads evenly, covering the board in a thin, even layer that dries quickly to create the perfect surface for your artwork.

9. Apply Clear Acrylic Sealer:

Mod Podge Clear Acrylic Sealer is another type of glue sealer you can use on cardboard before painting. It’s easy to apply with a sponge brush or rolling it on, and it dries quickly to create a good base for your artwork.

10. Use Contact Paper:

Contact paper is a versatile product that can be used for sealing walls in preparation for painting, or for coating cardboard surfaces. This is an easy coating to apply with a sponge brush or rolling, and it creates an airtight seal when applied to porous surfaces.

Some Tips and Tricks:

1. Be sure to follow the recommended shelf life of your paint. If you choose to use a latex sealer, remember that latex takes a long time to dry, and it will take approximately 24 hours in a well-ventilated area for it to be ready to paint.

2. You can use gesso (a primer paint) to seal your cardboard before painting if you want an incredibly smooth surface. Just let the gesso dry thoroughly before applying your base color.

3. If you are using spray paint, be sure to cover everything in a well-ventilated area and wear eye protection and gloves.

4. You can choose to sand your surface lightly before painting if you want an especially smooth finish.

5. If you are using acrylic paint, be sure to clean up immediately with water and soap, or else the paint might discolor with the sealer over time.

Some Tips and Tricks:

6. If there are gaps in your finish, you can use a matte finish sealer spray over your final product to fill in the holes and smooth out the surface.

7. Test out your sealer on a piece of cardboard or poster board first to ensure that it works as expected and doesn’t alter your paint color.

8. If you are covering up printed images, apply many coats of sealant before painting so as not to smudge ink onto your surface.


Sealing cardboard is a necessary step before painting. If you don’t, your paint will likely peel off, and the cardboard may even warp or curl up on itself with time. To seal it, use an acrylic primer and cover the entire surface of the board with a coat.

Let dry completely before continuing with any other steps in your project, such as painting or cutting out pieces. Remember that sealing only works if done properly! We hope this blog on how to seal cardboard for painting has been helpful. If you have any other questions, feel free to comment below!

Jennifer Branett
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