How to Spray Paint Cardboard

Introduction

The spray paint is a line of paints that are used with an aerosol can. The name can be misleading, as the paint does not always need to be applied using an airbrush or spraying mechanism.  Aerosol spray paints are most often used in graffiti art, interior design, and automotive painting.

How to Spray Paint Cardboard

The paint comes with a propellant gas inside the can that mixes with the liquid, causing it to expand. The eruption of the mixture pushes an internal piston downward, which forces the paint out through an opening from the can nozzle. In this article, I will discuss how to spray paint cardboard. So let us get started.

Difference Between Spray Paint and Normal Paint

Spray paints are generally used for outdoor purposes or for adorning the wall of your house. This paint makes your walls look like they have been professionally painted with a brush. The difference between spray paint and regular paint is that spray paint has a more concentrated color while the other one does not have so much color.

Hence, when you use this, you require less material than traditional art material, which requires more materials than needed by using spray paints. But there is a downside to this thing: if it rains heavily, then all your hard work would be ruined because this type of painting cannot be washed off from the surface once it’s dry up ultimately.

So, in making sure your painting stays forever on the wall, you can use the special paint that sticks on any surface for good.

Step-wise Guide on How to Spray Paint Cardboard

1. Prep Work:

Spray paint will damage any surface you use it on, so the first thing to do is protect your preparation area with a tarp or drop cloth. A workbench stand is also handy for working at a comfortable height.

2. The Cardboard:

Any flat or corrugated cardboard you may have lying around can be used for this project. Most of it will be from boxes, such as paper towels and toilet paper cartons, milk cartons, etc., and most will square in shape; some large cereal box cardboard pieces might also be good candidates for this easy DIY spray paint job.

Avoid glossy cardboard that would require more extensive priming than we’re discussing here today.

2a. If you have some time on your hands, you can do a quick prep spray of the cardboard with an outdoor primer. I used KILZ because it doesn’t smell so nasty and will dry fast enough before going further.

Before Starting Painting 
Lay Down Those Cardboards

3. Priming:

The purpose of priming our cardboard pieces before spraying with a single color coat of spray paint is twofold: firstly, primers can sometimes seal up existing surface defects and help prepare the target surface for a good finish. Secondly, primers can sometimes influence how the final spray paint color turns out; in some cases, this is desirable, but it’s not helpful in others.

This means that if you’re going to be painting something dark or black (like we are), then using a gray primer as we did here will affect how the final piece looks when it dries – and make it lighter than perhaps what you had planned for initially. Another point of note: some paints require priming while others do not. Check the instructions that come with any paint product before proceeding further!

4. The Surface:

What I’ve used here is cardboard from some old paper towel rolls that I had lying around from a previous project, but again – you could use any flat corrugated cardboard that you may have lying around waiting to be upcycled into. Something fun like this! The other thing that you need is a mask; the type of painter’s variety will do nicely.

Some household parts stores do have masks on hand for sale (or rent) for those worried about breathing in paint fumes or having a reaction to any of the chemicals used in spray paint. The final thing that we’re going to use here is some newspaper or other form of paper, such as grocery bags, since cardboard is very absorbent and needs something to dry it off quickly, so the paint doesn’t keep soaking in once we’ve applied it.

5. The Spray Paint:

For virtually any surface you want to paint, you need to use an exterior type of paint intended for long-term contact with the elements and will withstand normal wear and tear of normal usage. This means that ordinary interior paints are not always suitable; however, most exterior grade paints generally work well.

Doing Spray Painting
 On Cardboard

In today’s tutorial, we’re using Rustoleum Universal in flat black ($5 at Home Depot) – but really, this could be any spray paint. There are only two exclusions to this: Do not use enamel or high gloss lacquer type paints, as these will require much more prep and special preparation before we can even attempt any painting.

Enamels are very common in the spray paint world and often have a blue or white pigment base; spraying an enamel would be far too tricky with everything we’re trying to accomplish here.

6. The Cardboard:

The cardboard needs a little sanding down before spraying because there can sometimes be a thin layer of wax coating the surface, inhibiting paint adhesion. The best way to sand at cardboard is by using an ordinary medium grit sanding block or even some fine sandpaper sheets – make sure not to overdo it! Again, we’re not looking for toothpaste-like smoothness here – we want to take off any visible dirt and grime that might have accumulated from use.

7. Prep:

With all our prep work done, it’s finally time to spray! I recommend using an inexpensive HVLP (High Volume/Low Pressure) air gun; this type of device exerts minimal backpressure, so you don’t need special equipment or anything like that, but it will help make your spraying a little easier.

Of course, if you have a compressor and an airbrush, then definitely feel free to use those, but the HVLP works just as well for this purpose (and is less expensive).

The other thing to remember here is that spray paint tends to separate in the canister if it’s not used often enough; if you shake up the canister before using it (as usual) but see that there’s still separation after 5-10 seconds or so it means that your paint will probably be clogged – go ahead and clean out the nozzle with some paper towels first so that you don’t get any drips!

8. The Spraying:

Now we’re ready to begin painting, but please note that this process is not as straightforward or as quick; you have to be patient!

The first thing that I did was spray down a few sheets of newspaper and then crumple them up, covering the cardboard piece with several layers so that I could move onto the next step while my paint was drying. It’s important to apply multiple light coats rather than just one heavy coat since we want our layers to dry quickly.

Once we’ve applied about three-four medium coats (as shown above), let it all sit for about 10 minutes before using another set of light coats until you get an even, saturated appearance – it’s hard to judge by simply looking at it whether your cardboard has taken on too much paint, so you’ll have to be patient here and see if everything looks right when it’s all done.

It took us about four sets of light coats for our booster box before we felt that the paint looked correct, but your mileage may vary; this is a process that can take some time to master!

9. Varnish:

Once you’re finished with your painting, let it dry thoroughly (overnight is best) and then finish off the piece by spraying on some regular spray varnish – this will add additional protection for everyday wear and tear while adding an extra sheen to your cardboard’s coloration.

We used something called “Matte Varnish” (which comes in a flat black/brown color) since we wanted our cardboard to look like it was made from wood or something similar, but if you want a shiny finish, then feel free to use any high-gloss spray varnish that’s available – be sure not to go overboard with the application, and do multiple light coats rather than one heavy coat. Enough said!

10. The Finished Product:

And here we have it – our now-finished product complete with anime art; as shown here, this type of Cardboard can hold up exceptionally well when used for props despite its low cost and ease of construction, making it perfect for beginners.

Precautions While Performing How to Spray Paint Cardboard

  • Spray painting cardboard can be fun and rewarding. However, spray painting is not as simple as other spray paint projects because the cardboard absorbs many paints. If you’re new to spray painting, practice on some inexpensive cardboard. It’s better to test your techniques before using suitable materials or working on a substantial project.
  • When choosing a porous surface like cardboard for a base coat, it helps if you prime the surface first by sealing the fibers with a primer (before applying spray paint). This will reduce the amount of dripping that occurs when spraying heavier colors over dark surfaces.  You may need to use several light coats of primer rather than one heavy coat.
  • Always hold the can at least 12-18 inches from the surface and spray in a sweeping motion, moving up and down or side to side. Apply a light misting coat first so you can see where you applied paint. Then use additional thin coats until the cardboard is completely covered. You’ll find that it isn’t necessary to follow any complicated patterns when applying spray paint (like using different types of strokes). Instead, the color will be uniform if you move back and forth over the material with your technique.
  • Cardboard absorbs more paint than wood, plastic, or metal, so when painting on cardboard, gradually increase the distance between you and the item being painted until you are spraying from a distance of about 15-18 inches.
  • Spray painting on something like cardboard is not very forgiving, so make sure to practice your technique before using suitable materials or working on a substantial project.

The Alternative of Spray Painting on Cardboard

Spray painting with a spray gun on cardboard is not widely used. In addition, ass spray painting involves several distinct processes, and it is more expensive than other standard methods to include screen printing and pad printing.

Though the painted surface of cardboard will last longer than that painted by traditional paint brushes, spray paint is challenging to stick smoothly on any cardboard without air bubbles or dust collisions. It requires high spraying skills and an exact calibration between opening size under nozzle and thickness of the material itself.

If one wants to make extra-large products over 50 square meters, some problems need solutions, such as making wooden frames for each piece and assembling them manually. The factors like moisture-proofness, temperature-resistant and durability are not met as the surface is very smooth after spray-painting.

The Alternative of Spray Painting on Cardboard

Which Primer is Suitable for Cardboard Painting?

Cardboard absorbs more paint than wood when painted with acrylic paints. For that reason, polyester or alkyd primer would be a good choice for you to spray paint cardboard.  If the cardboard surface is coated with oil paint before spraying, polyester or alkyd primer can be used;

however, if it is not applied before painting, then wax emulsion should be used instead due to its better adhesion oily surface. Follow the chart below for an appropriate primer selection.

If your object needs outdoor protection after painting, coat it with an epoxy resin-based coating (with at least 3 layers). The thickness of one layer should be around 50 microns, and 1MPa build-up pressure could easily reach 25 microns.

And for woodworking, you could use less primer, and 1 to 2 layers are enough. For indoor furniture spraying, purchase a high build primer that can be sprayed at 20 microns in a single layer (the thickness varies depending on the type of paint used). For outdoor painting, choose an exterior primer with suitable water resistance and chemical resistance. It should have 60-micron thick build-up pressure with sufficient coverage too.

Conclusion

I hope this article has been beneficial for learning how to spray paint cardboard. Ensure proper safety while performing the process. Thank you and have a nice day!

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