Cardboard is one of the most versatile, economical, and simple DIY materials available. You can never go wrong with cardboard, whether you’re recycling old cardboard to build a new craft or making a signboard.
While corrugated cardboard is simple to bend, shape, and cut, painting it can be difficult. Because cardboard is composed of delicate craft paper, it is prone to warping, wrinkles, and bleeding if too much or the wrong paint is used.
It’s not like other drawing materials or canvas, where you can freely express your creativity.
There are a few things to keep in mind while working with cardboard and being more selective of paints is the first significant factor. In our guide, you can learn more about painting on cardboard, the materials you need to use on cardboard, and how to prevent warping.
By the end, you’ll have lots of information about how to tackle your next cardboard painting art projects using a protective surface before and after you paint. (Learn How To Dull A Glossy Finish)
Does Cardboard Warp When Painted?
Because cardboard absorbs too much moisture, water-based paints, such as acrylic paint, can readily warp when painting a cardboard box. If you try to paint carton cardboard with a thick layer of acrylic, even with a paint primer, you risk allowing water to soak in.
Because paint soaks into the porous surface of cardboard, you can’t use any paint on it. Painting cardboard produces different outcomes depending on the paint kind and procedure you employ and the quality of the cardboard after it has been painted.
Paint options you can choose include:
- Watercolor Paint
- Acrylic Paint
- Spray Paint
- Oil Paint
Corrugated cardboard is like heavy-duty paper that isn’t water-resistant. As a result, watercolors are not the preferred medium. Water is not required for both acrylic or spray paint.
Acrylic or spray paint works best on corrugated cardboard out of these three colors. Oil-based paint, especially when applied in heavy layers, has enough moisture to warp delicate kraft paper. The other two options are preferable.
However, to keep the material from warping, prime the cardboard by applying gesso, and apply your paint in thin coats.
Using a primer helps the paint adhere and lasts a long time.
Gesso is an acrylic primer that also serves as a moisture barrier. It creates a rough surface for the paint to adhere to while also enhancing the colors in your artwork. Most gesso is white, but if you want the cardboard color to show through, clear gesso is available.
A transparent acrylic medium is typically more desirable with a wood surface than colored gesso. Still, you could use it for a smoother surface when oil painting or acrylic painting on cardboard and canvas.
- You can use white acrylic paint for a white base, although gesso is a better solution. You can also add a few drops of acrylic paint to change the gesso color.
- Paint the first coat onto the cardboard, and use thin layers of gesso and a flat brush for bright colors.
- Let your gesso dry for 24 hours and apply a second coat to get the best results.
- Paint in opposite directions to the first coat for a smooth, even base.
- Let your gesso layers dry for another 24 hours.
- If you can still see your cardboard beneath your gesso, wait another 24 hours before you apply a third coat.
- Sand the surface of your cardboard using 500-grit sandpaper if you feel a rough surface. By nature, you get this roughness so the paint can stick, but if you like to paint on a smooth surface, sand your gesso layers.
It is possible to make your own gesso using chalk, white paint, white glue, and water. (Learn How To Paint Glass)
Painting Cardboard Without Warping
Many painting styles need you to dip your brush into the water while painting. Water will warp your cardboard. Watercolors and poster paints are the two primary options not suited for painting cardboard box.
While you can avoid warping or curling by painting with a dry brush foam brush, the bristles can feel hard and stiff, and you may not get the effect you want.
Painting with Acrylics
To avoid warping, paint the cardboard with a dry brush or sponge. When cardboard is exposed to
moisture, it curls or warps.
- Before you paint, don’t wet the brush or sponge. Use a dry brush instead. Bend the bristles back and forth with your fingers if the brush seems stiff.
- Because watercolors require water, they don’t work well on cardboard. Instead, use acrylic paint or oil-based paint.
- To stop cardboard curling, apply the paint immediately to your brush or sponge. Instead of squeezing paint directly onto the cardboard, dip the brush into the paint or squeeze a few drops into the sponge.
- To avoid warping, apply extremely thin coats of paint. The less moisture that is exposed to the cardboard at one time, the less it will distort. Apply a thin coat of paint and let it dry completely before adding another.
- Allow 2 hours for the paint to dry before applying a second layer. Although the first few layers may be slightly see-through, it’s preferable to have to apply multiple coats than to have your cardboard distort!
- When you apply multiple layers of paint, the more even and solid your end results will be. Continue painting until you’re happy with the results. Your first few coats can still show the cardboard underneath.
- Apply a second coat of paint after 2 hours. To avoid warping, make sure the cardboard is completely dry before applying a second coat.
- Allow about 2 hours of drying time between each additional coat if you wish to do a third or fourth coat.
Spray Paint on Cardboard
Spray paints make a great alternative when painting cardboard because spray paint is easy to apply. Spray paint cans are available at any hardware or art supplies store.
It would be best if you did spray painting in a ventilated area. According to the US Consumer Product Safety Commission, water-based acrylics are poisonous if consumed, and solvent-based paint fumes can be toxic.
Make sure you’re in a well-ventilated environment with plenty of airflow. Spray painting cardboard is best done in a warm, dry location that is entirely protected from the elements. A garage, for example, provides protection from the elements such as wind, cold, and rain.
Prepare Your Work Area
Spray paint is challenging to get rid of. Take a moment to prepare the work environment and yourself before you begin.
To avoid painting the ground, cover it with an old sheet, newspaper, or another piece of cardboard. Wear an protective clothing, a face mask, and gloves. (Learn How To Get Paint Out Of Hair)
Shake Spray Paint
Because spray paint pigments separate with time, you should shake the can for at least three minutes before using it. Shaking the pigments helps them blend, and the color should have an equal gradient.
It’s also an excellent idea to re-shake the can now and then to maintain the paint flowing freely.
Lightly Spray Paint
- Hold it 12 inches away from the cardboard when the can is ready and parallel to paint in a thin layer. If you get too close, the paint will pool and warp.
- You can try unique patterns instead of just moving the can from left to right. Avoid the temptation to spray onto the cardboard more than twice, as warping on cardboard boxes is caused by over-saturation.
- Allow at least two hours for the initial layer to dry.
Apply a Second Coat
- Apply a second layer when the first has dried. You risk warping the paint if you don’t wait for it to completely dry.
- Consider using a contrasting color for the second layer and spray with light sprays using the same approach as before. Let the paint dry between any coats.
- Continue with a third or fourth layer if you need a more solid hue.
How Do You Fix Cardboard Warping?
Moisture is the leading cause of warping for paints you use on cardboard. Here are a few tips to prevent warping or curling:
- Don’t over-saturate when you paint on cardboard.
- Keep moisture away from the material.
- Avoid high humidity.
- Use gesso primer before painting.
- Add paint to the brush instead of squeezing paint straight onto the cardboard.
- Allow coats to dry before adding more to get an opaque and bright print.
- Never use watercolors or add too much acrylic paint direct to cardboard.
- Use double or triple-walled, thick corrugated cardboard.
How to Fix Warped Cardboard
Cardboard is an excellent painting medium, but if you use too much paint or ink, the cardboard can twist or curl.
Luckily, you can fix warped cardboard with a few tips and techniques if the damage isn’t too severe.
Follow these step-by-step instructions to fix your painting.
What You Need:
- Spray bottle
- Water
- Weights or heavy objects (Books or furniture are easily accessible)
Completely Dry
Allow the cardboard to air dry until it is completely dry. Place the artwork in a safe, out-of-the-way location for a few days.
Spritz with Water
Rehydrating the material is the first step in reshaping it. Using a spray bottle, wet the cardboard. Never submerge the board in water or allow the material to become too wet. The pulp will pull away from the base if you get it too wet.
Weigh it Down
Then, with the curls pointing upwards, place the board on a flat surface. To keep the cardboard flat, lay a flat piece of plywood over it and place your weights or heavy things on it. Books are a great tool, but anything substantial should be enough to weigh it down. (Learn When To Remove Painters Tape)
Wait
Allow between 24 and three days for your painting to dry in this position. You can lift the objects once the cardboard is totally dried. The painting must be completely flat, with no warping or curling. If not, go through the process again. Recovery can take weeks sometimes.
More tips to prevent warping
You might accidentally put too much paint on your cardboard or leave it in an area with a lot of moisture, which will cause it to warp or curl. There is still a way to repair the damage if it isn’t too bad.
Paint a Box
A small amount of Styrofoam prevents your cardboard from curling. Expanded polystyrene foam, which does not distort, is an excellent way to fill any box. As a result, it won’t warp when you load your cardboard with the substance a little. There is enough tension to prevent warping if you paint a box with enclosed sides.
Acrylic, Spray, Enamels, or Oil-Based Paints
For cardboards, watercolors are strictly prohibited. It transports water-soluble compounds and aids in the easy shrinking and curling of cardboard. As a result, you must select the paint carefully to prevent it from warping. Choose non-damaging paints to use on your corrugated cardboard.
Acrylic paint is the best for painting while also lowering the risk of warping the cardboard. Acrylic and spray paints can be used directly on them. Enamels and oil-based paints are also suitable for use on cardboard. These paints are not as wet as watercolors, making them ideal for use on cardboard. However, too much oil paints in one area can soak into the cardboard surface.
Better Cardboard
The thin cardboard distorts. Paint and wetness don’t stand a chance on single-layered cardboard. After the paint, it also appears flimsy and unpleasant. As a result, one more cardboard can be glued together perpendicularly to improve the condition. This will help to keep the cardboard in good shape and prevent warping.
Let Gesso Dry
You can often be too eager to get your first coat of paint onto your primed cardboard.
