Since most plastic is smooth, you want to rough up the surface a bit to give the paint something to stick to. Fine sandpaper will rough up the smooth surface without leaving visible sanding marks, so make sure to keep it to a fine grit.
If painting interior plastics, apply a high-adhesion latex stain-blocking primer. For outdoor plastics, spray-prime with specialized primers formulated specifically for adhesion to plastics.
The easiest way to seal acrylic paint on plastic at home is to use a polyurethane sealer made especially for plastic surfaces or a clear acrylic spray sealer. This will provide the best adhesion to the plastic material and create a durable finish by preventing paint flaking off.
Acrylics work really well on plastic. If the plastic is nice and rigid it will stick well to it. If you're worried about the paint chipping/peeling you can definitely use a spray primer first, paint and then seal with a varnish.
Method 1: Use Spray Varnish
First, lay down some old newspapers or anything else to protect surfaces around your work area. Next, hold the can about 12 inches away from the painting and evenly spray the surface. Allow the first coat of sealer to dry completely before applying a second coat.
When spray painting plastic that is soft, like vinyl, a flexible paint is required, and acrylic-based paints and urethane modified acrylic paints adhere better without cracking, flaking, or peeling. Overall, oil-based paint isn't a good spray paint for plastic as it doesn't bond well.
From my interpretation of your question, you are looking for a clear primer or adhesion promoter. PlastiCote makes a product they call clear primer and adhesion promoter. Rustoleum makes a clear primer spray as well. Both products are intended for automotive use, but are claimed to work well on most plastics.
First, make sure you're using a priming solution designed for use with acrylics. This will help to create a smooth surface for the paint to adhere to. Second, avoid using too muchpaint on your brush . Not only will this make it more difficult to achieve even coverage, but it can also make acrylic paint peel and crack.
Standard exterior gloss paint is a suitable finish for plastic when used in conjunction with an appropriate primer and undercoat. Either acrylic or oil-based gloss can be used, and both are available in a wide range of colours. Typical application methods include brush, roller and spray.
To paint plastic effectively, you must have a good-quality paint and primer that will both ensure you get long-lasting, beautiful results. When it comes to paint for plastic, our experts always recommend Zinsser Allcoat Exterior as the best, especially for the average DIY'er.
New Unprimed Parts. Painting new unprimed plastic first requires a thorough cleaning of the part: soap and water washing, removing mold release agents, chemical cleaning and inspection are all parts of the pre-sanding cleaning. The part must be sanded and cleaned, then anti-static and/or adhesion promoter is applied.
Best glue for hard plastics
Ordinary white glues, wood glues, or common adhesives won't react well or form permanent bonds with these plastics. For the strongest glue to use on harder plastics try Loctite Plastics Bonding System, a two-part cyanoacrylate adhesive.
“The best way to apply spray paint to a plastic surface is to always clean first and then lightly sand the piece if there are loose debris. Then, use Krylon Fusion All-In-One spray paint for the best adhesion!”
Peel Stop® tightly bonds to old paint and problem areas forming a sound surface for new paint. Peel Stop® forms a tough acrylic film that stays flexible and helps prevent peeling by letting moisture escape. A clear sealer, Peel Stop® works like nothing else to stop peeling problems on old or new surfaces.
Use A Primer
It creates an adhesive, smooth layer for the paint to stick to. Although there is nothing wrong with applying the primer using a paintbrush, it may cause streaks on the surface. Alternatively, we suggest using a spray-on primer that has been made specifically to work alongside plastic aerosol spray paints.
Additionally, using a primer specifically designed for plastic can significantly improve adhesion. These primers form a sticky base that helps the acrylic paint to stick better and last longer. After priming, applying the acrylic paint in thin, even layers allows for better adhesion and durability.
The best way to avoid ruining an acrylic painting is to apply sealant to your painting. The best ways to seal an acrylic painting is to use an acrylic resin varnish, acrylic polymer varnish, clear sealer, or mod podge, depending on the surface you are painting on.
What's the Best Spray Paint for Plastic? Choosing the best spray paint for plastic is a similar approach to choosing the best spray paint for wood. Rust-Oleum Universal and 2X Ultra Cover spray paints are both designed for use on plastic.
Lightly sanding the plastic surface creates a slightly rough texture that helps paint adhere better. Use fine-grit sandpaper (180 to 220 grit) and sand in a circular motion, being careful not to scratch the surface. Wipe away dust with a clean, damp cloth and allow the item to dry.
Spray paint works especially well for plastic, but you can use acrylic or enamel/model paint as well. It would be even better if the paint is meant for plastic. Check the label, and look for words such as: "Plastic" or "Multi-Surface."
The most common cause of paint peeling (or delamination) is due to inadequate surface preparation. In the case of plastics, you also need to consider the surface tension of the plastic and the surface tension of the primer coating (1st layer). The second most common reason for peeling is solvent entrapment.