Enamel and acrylic paints are both popular options for DIY and craft projects. But can you safely apply acrylic paint over an enamel painted surface? The short answer is yes, you can paint acrylic over enamel under the right conditions.
Enamel and Acrylic Paints
Before diving into the details of painting acrylic over enamel, it helps to understand what exactly enamel and acrylic paints are.
What is Enamel Paint?
Enamel paint is a general term for paints that dry to a hard, durable, glossy finish. The term “enamel” refers to the high-gloss surface enamel paints can produce.
Enamel paints come in solvent-based and water-based options:
- Solvent-based enamel – Also called oil-based or traditional enamel, solvent-based enamel contains alkyd resins suspended in petroleum distillates. It dries through solvent evaporation.
- Water-based enamel – Uses acrylic resins suspended in water. It dries through water evaporation. Water-based enamel is lower odor and lower VOC than solvent-based.
Both types provide an extremely hard, scratch and chip resistant finish. Popular uses for enamel paint include:
- Automotive and machinery finishes
- Metal furniture and fixtures
- Outdoor signs
- Model paints like those used on cars, planes, trains
- Household appliances
- Tools, equipment, industrial coatings
Enamel paints cure through a process called oxidization, where they react and cross-link with oxygen as the solvents evaporate. This forms a tough, bonded polymer layer.
What is Acrylic Paint?
Acrylic paint contains pigment particles suspended in an acrylic polymer emulsion. The acrylic binders are water-soluble, so acrylic paints are water-based. As the paint dries, the polymers cross-link together, forming a durable plastic-like film.
Key properties and uses of acrylic paint:
- Fast drying time
- Thin with water
- Less toxic and lower odor than enamels and oils
- Used for painting, crafts, hobby models, murals, canvases
- More flexible finish than enamels
Acrylics provide a matte, satin, or semi-gloss sheen depending on the formula. They are easy to apply and clean up with water. Acrylics also resist cracking, fading, and yellowing better than oil-based paints.
Can You Paint Acrylic Over Enamel?
Yes, acrylic paint can be applied over enamel paints as long as proper painting techniques and surface preparation are used. There are a few considerations to keep in mind:
1. Allow Enamel to Fully Cure
One of the most important factors is making sure the enamel has had time to fully cure and harden before painting over it:
- Solvent-based enamel – Allow at least 1-2 weeks drying time before applying acrylics. Solvent-based enamels take longer to fully harden.
- Water-based enamel – A minimum drying time of 24 hours is recommended before recoating with acrylic.
Rushing the recoat time can cause the acrylic paint to wrinkle, crack, or lose adhesion. This is because solvents become trapped in the uncured enamel layer which interfere with proper curing of the acrylic.
Always check the manufacturer’s recommended recoat times for the specific enamel paint used. If unsure, allow for longer dry times.
2. Properly Prepare the Enamel Surface
Taking steps to prepare the enamel surface helps acrylic paint better adhere:
- Lightly sand – Using fine 320-400 grit sandpaper, lightly sand the enamel to remove any gloss and provide some tooth for the acrylic paint. Be careful not to sand through the enamel.
- Clean and degrease – Wipe the surface with a tack cloth to remove sanding dust. Follow with an ammonia-based degreaser to remove any oily residues from the enamel.
- Apply primer – For best adhesion, first apply a layer of multi-surface primer over the prepared enamel. Oil-based primers work best for this application.
- Scuff the surface – If sanding is not possible, just scuffing the surface with a red Scotch-Brite pad can help.
Proper preparation gives the acrylic paint something to grip onto. Skipping this step risks poor adhesion and chipping or peeling paint.
3. Test Acrylic Compatibility First
It’s always a good idea to test the acrylic paint on a small inconspicuous area first. This helps confirm if the paint will adhere properly without any reactions:
- Apply a dime-sized amount of acrylic paint over the prepared enamel surface.
- Allow to dry fully, then inspect adhesion.
- Check if the acrylic paint wrinkled or caused any reactions in the enamel.
- If the acrylic paint adheres smoothly and evenly with no reactions, it should be safe to proceed.
Testing first is particularly important if painting over old or unknown enamels. This provides peace of mind that the paints are compatible.
4. Apply Thin Coats of Acrylic
When painting acrylic over enamel, apply thinner coats instead of thick layers:
- Thin coats allow for better adhesion and drying.
- Thick globs can slide around resulting in uneven coverage.
- Multiple thin coats are better than one thick coat.
5. Allow Proper Dry Times
Acrylic paint dries fast, within 30 minutes to 1 hour. But when applied over enamel, longer drying times are recommended:
- Allow the first coat to dry for at least 24 hours before adding another coat.
- If multiple coats are needed, wait at least 8-12 hours between coats.
- Drying times prevent trapped moisture and adhesion problems.
Rushing the paint job risks cracking, bubbling, or delamination when painting acrylic over enamel. Patience leads to the best results.
Key Considerations for Acrylic Over Enamel
There are a few other factors to keep in mind when using acrylic paint over enamel:
Use Acrylics Over Enamel Only
In general, acrylics painted over enamels are much safer than the reverse:
- Acrylics are very sensitive to the strong solvents in enamel paints.
- If enamel is applied over acrylic, the acrylic paint can liquify, wrinkle, or lift.
For best compatibility, use acrylic paints as a topcoat over cured enamel only.
Solvent-Based Enamels Require More Caution
Oil-based enamels contain stronger solvents compared to water-based:
- Only use acrylics over fully cured solvent-based enamels. Allowing proper dry time is critical.
- Scuffing and priming provides important added adhesion over slick oil-based surfaces.
Water-based enamels provide a safer, more compatible base for acrylics. But proper cure time is still required.
Enamels May Require Multiple Coats for Full Coverage
Depending on the color used, enamel paint can require several coats for an opaque finish.
If the enamel base coat appears thin or uneven, apply additional acrylic paint coats until the color looks solid. Acrylics adhere well to themselves for building up layers.
Acrylics Won’t Self-Level Like Enamels
The smooth, glass-like finish of enamel paint comes from its self-leveling properties. Acrylics do not self-level as well:
- Applying acrylic over textured or brushed enamel may retain some of the underlying texture.
- Acrylic has a thicker consistency and dries faster than enamel.
Thin coats and allowing proper drying time helps improve the smoothness of acrylics over enamels.
Painting Acrylics Over Enamels on Different Surfaces
The techniques for painting acrylic over enamel apply to a variety of different surfaces:
Wood, MDF
Acrylic adheres well over enamels on wood and MDF if proper prep is done. The porous nature of wood allows for good mechanical adhesion of the acrylic paint.
Light sanding followed by a primer coat ensures acrylic compatibility over enamels on wood.
Metal (Steel, Aluminum)
For exterior metal surfaces, acrylics provide good durability and color retention over enamels. Make sure to allow for proper enamel cure times.
On interior metals, if the enamel ever chips or peels, moisture can get trapped between the coats of paint leading to more chipping. Using an oil-based primer helps prevent this.
Plastics
Plastics like PVC, ABS, styrene are common materials used for models and miniatures. Acrylic adheres well over enamels on plastics with proper prep. The smooth non-porous surface necessitates sanding or scuffing before painting.
Walls
For interior walls already painted with enamel, applying acrylic paint is possible. The techniques are similar to those used on other surfaces:
- Allow the existing enamel paint to fully cure, at least 1-2 weeks is recommended
- Lightly sand the walls to remove gloss and improve acrylic adhesion
- Clean sanded walls thoroughly before painting
- Use an oil-based primer for maximum acrylic adhesion
- Apply acrylic paint in thin, even coats following drying times
Walls may require an extra coat of acrylic paint to hide the existing color compared to other surfaces. Acrylics are well-suited for walls thanks to their durability, low odor, and easy soap and water cleanup.
Canvas, Fabric
Acrylic paint works extremely well over enamels on canvas or fabric surfaces. The flexible nature of the canvas allows the acrylic paint to adhere as it expands and contracts:
- Stretch canvas over a frame before applying enamel paint
- Once enamel is fully cured, paint thinned acrylic in layers
- Softer artist brushes should be used on fabric surfaces
- Allow ample drying time between acrylic coats
The adhesion strength and flexibility of acrylics makes them ideal for painting over enameled canvas art or fabric.
Clay Pots, Ceramics
For painting acrylic over enameled clay pots or ceramics:
- Scuff glazed surfaces with sandpaper to improve acrylic adhesion
- Wash and rinse the pottery before painting
- Use a specialized bonding primer made for ceramics and pottery
- Apply thinned acrylics in multiple coats for complete coverage
Acrylics bond well to bisque fired or terra cotta clay. Extra conditioning is needed for smooth glazed ceramics to accept acrylic paint.
Miniatures
Models, miniatures, and collectible figures are often painted using enamels. Acrylic paints can be safely applied over cured enamel:
- Disassemble models for easiest painting access
- Lightly sand shiny plastic or metal miniatures before painting
- Use thin coats of acrylic paints instead of thick layers
- Allow paint to dry fully between coats
The biggest key is allowing ample time for enamels to cure before painting details or finishing with acrylics. This prevents solvent entrapment and paint reactions.
Automotive Surfaces
On vehicles or motorcycles, acrylic urethane paints are commonly used over enamel primer:
- Apply 1K or 2K urethane primer-surfacer
- Once primer fully cures, sand and prep the surface
- Mix and activate acrylic urethane paint per manufacturer instructions
- Spray apply acrylic urethane using proper spray technique
- Allow sufficient flash time between coats
Using acrylic urethanes over enamel primers gives strong adhesion and durability for automotive finishes. Proper spray techniques and dry times must be observed.
Common Questions About Acrylic Over Enamel
Here are answers to some frequently asked questions about using acrylic paint over enamel:
Is It OK to Paint Acrylic Over Oil-Based Enamel?
Yes, acrylics are safely and commonly used over oil-based enamels, as long as proper drying times are allowed. Oil-based enamels require at least 1-2 weeks drying before recoating with acrylic.
What Kind of Primer Should I Use Before Painting Acrylic Over Enamel?
An oil-based primer designed for multiple surfaces provides the best results before painting acrylic over enamel. This helps block any oils from the enamel and gives strong bonding power.
Do I Have to Sand Enamel Before Painting Over It With Acrylic?
Lightly sanding the enamel before painting is recommended to improve adhesion, but is not absolutely required. Scuffing the surface with sandpaper or a red pad provides added grip for the acrylic paint.
Can I Paint Acrylic Enamel Over Regular Acrylic Paint?
Yes, acrylic enamel formulated paints are compatible over plain acrylics. The “enamel” refers to an acrylic paint with harder, more scratch resistant properties, not a true enamel.
How Long Should I Wait Before Painting Acrylic Over Water-Based Enamel?
A minimum drying time of 24 hours is recommended before painting acrylics over a water-based enamel. Longer is better to allow for full curing. Always follow the manufacturer’s recoat guidelines.
What Happens if You Paint Acrylic Too Soon Over Enamel?
Rushing the recoat time risks poor adhesion, wrinkling, cracking, or chipping when painting acrylic over enamel. Acrylics require enamels to be fully cured to prevent trapped solvents from interfering with drying.
Conclusion
Painting acrylic over properly cured and prepared enamel surfaces can produce beautiful, long-lasting results. Paying attention to recommended drying times, surface preparation, careful application, and compatibility testing helps ensure success with this painting technique. Allowing enamels adequate curing is key before sealing them under acrylic paint.
With some basic preparation, acrylics provide strong adhesion over enamels on metal, wood, canvas, walls, automotive finishes, miniatures, pottery, and more. The versatility and durability of acrylic paint makes it ideal for use over pre-existing enamel paint jobs. Just be sure to have patience and allow the enamel time to harden fully before coating over it with acrylics.
