When it comes to painting plastic, the big decision is which paint to use. That’s because not all paints will stick to the slick non-porous plastic material. So can enamel paint be used on plastic? Here is the answer to that.
Enamel paint can be used on plastic as long as the plastic surface is fully prepped. This is because enamel paint is ideal for non-porous surfaces like plastic. Not just that, enamel paint is also perfect for surfaces that will experience heavy use and materials like plastic that would be washed.
However, before painting enamel on plastic, the plastic surface has to be washed and sanded. This is to improve paint bonding and smoothness.
But that’s not all. There is more to know about using enamel paint on plastic and this post digs right into the topic. So let’s dive in to explore more.
Does Enamel Stick to Plastic?
Enamel sticks to plastic. This is because enamel paints are usually oil-based and oil-based paints tend to stick better to plastic than water-based paints. The oil-based nature of the enamel paint means it contains strong chemicals that help the paint coating adhere well.
Also, enamel paints contain resins, usually alkyd resins that make the paint coating adhere better to plastic.
Usually, it’s very difficult for paint to stick to plastic. This is because plastic unlike wood is non-porous meaning that the plastic material has no grain, fiber, or thread. So ordinarily, there is nothing for the paint to soak into or stick to.
So it’s usually difficult for paints to stick to plastic. Water-based paints don’t stick to plastic. But enamel paints have a hack to bypass this paint adhesion problem.
Enamel paints especially oil-based enamel have a large volume of resinous compounds in them. Most oil-based enamel paints are designed with alkyd resins like glycerol (or glycerine). These alkyd resins are paint-modified polyester compounds that improve the enamel paint’s bonding qualities.
The alkyd resins and other oil-based chemicals in the enamel paint make it stick to plastic better than most paints. Also, some alkyd resins used in the makeup of enamel paints have a thermoplastic composition. Thermoplastics are plastic polymers that harden when exposed to cool air.
The hardened thermoplastics have similar characteristics to plastic material and this also allows the enamel paint stick when used to finish plastic materials including outdoor plastics, and hard plastics.
Tip: To make enamel paint stick better to plastic, you should use an oil-based primer first on the plastic.
How to Apply Enamel Paint to Plastic?
Applying enamel paint on plastic requires enough surface preparation. Without surface prep, the paint will peel quickly. To apply enamel paint on plastic, you’ll need the following tools:
- Dish Soap
- A Soft Sponge
- Fine-Grit Sandpaper
- Rags or Tack Cloth
- Rubbing Alcohol
- Painter’s Tape
- Spray Enamel
- Natural Bristled Paintbrush
- A Can of Paint Primer
- Polyurethane Sealant
Here is a quick rundown of how to apply enamel on plastic:
- Wash The Plastic Surface
- Apply Rubbing Alcohol on The Plastic
- Sand The Plastic Lightly
- Apply Two Coats of Primer
- Prepare The Enamel Paint (Optional)
- Apply Two Coats of Enamel on The Plastic
- Seal The Finish with Polyurethane (Optional)
Roll those sleeves and let’s get to work.
1. Wash The Plastic Surface
The next thing to do is to wash the plastic. This is to remove dirt and grime that can prevent the enamel paint from adhering properly to the plastic. Plastic does well to hide stains. If the plastic surface is riddled with debris and dust, it will ruin the finish.
To wash the plastic, mix dish soap in water. Then soak a soft sponge or rag in the mixture use that to scrub the plastic. When the plastic looks clean, it should be rinsed with clean water and left to dry.
2. Apply Rubbing Alcohol on The Plastic
Usually, after washing the plastic, there may still be hardened grease and oil on the surface. This is because dish soap doesn’t always degrease a surface. Also, there will be stubborn stains that will not come off with just dish soap.
So to remove grease and stubborn stains, apply a degreaser like TSD or rubbing alcohol on the plastic.
To do this, douse a rag with rubbing alcohol and use it to wipe the plastic. For hardened greasy stains, you’ll need to pour small rubbing alcohol on the affected spot. Then leave it for a few minutes before wiping it off with rags.
3. Sand Lightly
The next step is to lightly sand the plastic. This helps to give the plastic material a few teeth that the paint coating can adhere to.
To sand the plastic, use very fine sandpaper. This includes grit from 220 upwards. Any grit lower than this can damage the plastic and ruin the finish.
You should be careful with this step because if you leave scratches on the plastic, it will be evident when the enamel paint dries especially if you don’t use a primer.
Tip: The best way to sand plastic is to sand in swirls or circular motion.
4. Apply Two Coats of Primer on the Plastic
As explained earlier, plastic material is slick and non-porous. Though spray enamel will stick to plastic well, a coat or two of oil-based primer will help the enamel stick better. You can either spray the primer or apply it with a paintbrush.
After applying the first coat of primer, let it dry for about 30 minutes. Then apply the next coat.
Tip: Don’t apply more than 2 coats of primer on the plastic.
5. Apply Two Coats of Enamel on the Plastic
The next step is to apply the enamel. You should apply thin coats of enamel paint on the plastic. Thin coats are easier to control and they dry quicker. Thin coats also help to achieve a smooth finish.
After applying the first coat of enamel on plastic, wait till it dries. This will take a few minutes but before you can apply the second coat, let the first enamel coating dry for at least an hour.
If the enamel paint doesn’t come in a spray can, you should thin it with mineral spirits before using it on the plastic. This makes it easier to apply thin coats.
6. Seal the Finish with Polyurethane
When the enamel paint is dry, you should seal it with oil-based polyurethane. Polyurethane helps the enamel paint last longer on plastic.
This step is however optional. To seal plastic with Polyurethane, apply two coats of oil-based polyurethane on the enamel. Let’s go deeper into sealing enamel paint on plastic.
How Do You Seal Enamel Paint on Plastic?
You can seal enamel paint on plastic by applying a sealant or clear coat on the final coat of enamel paint. Sealing the enamel paint helps to make the finish last longer.
The sealant when dry will form a clear thick film on the enamel paint that will make the finish resistant to factors that can ruin it like moisture and dust.
Common choices to seal enamel paint on plastic include wax, acrylic clear coat, and clear enamel. But the best sealant to use for sealing enamel on plastic is oil-based polyurethane.
Sealing enamel paint on plastic means applying at least a layer of clear coat on the enamel finish. Usually, it’s best to apply two to three layers of a clear coat on the enamel.
However, it’s important to note that it’s not always necessary to seal enamel paint on plastic. Enamel especially oil-based enamel is very durable. So even if it’s not sealed, the enamel paint will still be durable enough to protect the plastic material.
But before you can seal enamel paint on plastic, the enamel paint coating has to dry. So how long does enamel paint take to dry on plastic? Let’s find out.
How Long Does Enamel Paint Take to Dry on Plastic?
It takes enamel paint between 1 and 24 hours for enamel paint to stick to plastic. On average, enamel paints will dry 6 hours after being applied to plastic.
Water-based enamel paints dry quicker than oil-based enamel. Water-based enamel paints can dry to touch in minutes and cure enough for recoat in 2 hours.
Oil-based enamel on the other hand can take up to 12 hours to dry and over 24 hours to dry enough for recoat or a sealant.
You should note that temperature variations and moisture also impact enamel paint’s drying time.
Enamel paints don’t dry as quickly as latex or acrylic paints. This is because of the oil-based nature of the enamel paint. Enamel paints are designed with synthetic and or natural oils that keep the paint particles from drying in the container.
When the enamel paint is applied to the plastic, these oils begin to evaporate due to exposure to heat and cool air. However, it will take a few hours for these oils to completely evaporate from the enamel paint particles. This is because these oils are naturally thick.
Water-based enamel paints dry quicker because the paint isn’t designed with oils. Instead, the paint uses water as its solvent and water evaporates quicker than oil.
Related Read: Can You Use Enamel on Wood Surfaces?
Does Engine Enamel Stick to Plastic?
Engine enamel sticks to plastic as long as the plastic surface is clean. Engine enamel is usually designed to be used on car and motor engines. But the enamel paint will also stick to plastic surfaces.
This is because engine enamel is designed with perfect bonding qualities to allow the enamel paint to stick to different parts of the engine.
Car and motor engines though largely metallic also have a few plastic parts. The block, cam covers, fuel lines, and oil pump in the engine are usually made from thermoset plastics or thermoplastics (thick plastic materials). These parts can be painted using the engine enamel as long as they are properly cleaned and degreased.
As an added advantage, engine enamel is great for outdoor plastic and hard plastic. This is because engine enamel is designed with improved heat resistance up to 100 degrees Fahrenheit. With this level of heat resistance, the plastic and the enamel finish will be protected against the sun’s UV rays.
Overall, enamel paint can be used on plastic materials. In most cases, all you need to apply enamel on plastic is to prepare the plastic material by cleaning and degreasing it.
You should also remember to prime before using enamel. This helps the enamel stick better to the plastic and it improves the durability of the finish.