Acrylic paint is a popular medium for creating outdoor murals and artwork. However, unlike indoor acrylic paintings, outdoor acrylics require protection from the elements to prevent fading, cracking, peeling, and other damage over time. Sealing outdoor acrylic paintings properly is crucial for longevity. This comprehensive guide will teach you everything you need to know about sealing acrylic paint for outdoor use.
Choosing the Right Acrylic Paints
When starting an outdoor acrylic painting project, it’s important to choose paints designed specifically for outdoor use. Here are some tips:
- Use acrylics labeled “outdoor” – These contain UV inhibitors and weather-resistant pigments. Some good brands are Golden, Liquitex, Winsor & Newton, and DecoArt.
- Avoid student grade/craft paints – Student acrylics lack the pigment load and durability needed for outdoor application. Opt for professional artist paints.
- Use permanent pigments – Certain organic pigments like alizarin crimson fade quicker outside. Choose colors with high permanence ratings.
- Lean towards matte/satin finishes – Glossy paints show weathering effects sooner. Satin or matte gives a subtle sheen but hides fading better.
Choosing paints designed for outdoor use will provide the longest-lasting, fade-resistant foundation for your mural or artwork.
Preparing the Painting Surface
Just as important as the paint is the surface you apply it to. Follow these tips for proper surface prep:
Clean and Dry the Surface
- Remove any dirt, grease, mildew or existing paint from the surface
- Allow the surface to fully dry before painting
- Porous surfaces like unsealed wood may require sanding for smoothness
Use a Primer
- Apply a quality acrylic primer made for exterior use
- Primers help paint adhere and prevents future flaking/peeling
- Tint primer close to your finished paint color for better coverage
Use Proper Sealing Techniques
- Seal porous surfaces like wood, concrete, plaster with exterior sealants
- Acrylic paint won’t bond well to shiny, non-porous surfaces
- Metals may require etching; plastics often need textured additives in paints
Prepping your surface properly gives the acrylic paint something secure to grip onto. Don’t shortcut this step!
How to Apply Acrylics Outdoors
When using acrylics outside, make sure to:
- Avoid painting in direct sun – Work in shade or overcast conditions. Acrylics dry too quickly in heat.
- Use minimal water – Thin paints sparingly and avoid wet blending. Too much moisture damages durability.
- Apply in thin layers – Brush on thin coats and allow paint to fully dry between layers. Thick paint is prone to cracking.
- Follow manufacturer instructions – Don’t skimp on number of coats needed for opacity and protection.
- Allow paint to cure fully – Acrylic paint continues to cure and harden for 1-2 weeks after drying. Avoid sealing too soon.
With care taken during application, your paint job will have the tooth and grip needed for long-lasting adhesion.
Choosing a Sealant for Outdoor Acrylics
Sealing is the final, critical step in protecting outdoor acrylics. You have several options:
Acrylic Varnishes
- Provide UV protection, water resistance, block dirt/pollutants
- Can be gloss, semi-gloss or matte finish
- Solvent-based offer better protection than water-based
Epoxy Resins
- Offer extremely durable surface coating
- Provide self-leveling finish and bright gloss
- Can yellow over time requiring recoating
Automotive Clear Coats
- Give an ultra tough, flexible weather resistant finish
- Require special spray equipment and safety precautions
- Can damage artwork if applied too heavily
Wax Sealants
- Offer minimal UV and water protection
- Provide soft satin finish and mild dirt resistance
- Must be reapplied frequently as it wears off
For most acrylic murals, an acrylic varnish or epoxy resin will provide the best sealing for outdoors.
How to Apply Sealants Over Acrylics
Follow these steps when sealing outdoor acrylic paintings:
1. Ensure Paint is Fully Dry and Cured
Sealant won’t adhere if applied over tacky paint. Wait the full curing time of 1-2 weeks.
2. Clean the Painting Surface
Wipe away any dirt, debris, overspray with a lint-free cloth before sealing.
3. Work in Thin, Even Layers
Apply sealants in 2-4 thin coats. Thick coats risk cracking, yellowing, and running.
4. Allow Proper Drying Time Between Coats
Follow manufacturer’s instructions, usually 24 hours between sealant coats.
5. Consider Adding Texture for Grip
Lightly brush, stipple or roll over final coat to help adhesion.
6. Seal Entire Painting Surface
Don’t miss edges or sides. Moisture can sneak in any unsealed areas.
Proper sealant application locks in paint and keeps the elements out. Don’t cut corners here!
Maintaining and Touching Up Outdoor Acrylics
Once sealed, outdoor acrylic paintings require minimal maintenance:
- Inspect art yearly for any signs of wear, lifting paint, etc. Catch problems early!
- Reapply protective sealer every 2-3 years, or whenever glossiness starts fading
- Use touch up paints and sealants to repair any damaged spots as needed
- Gently wash surface with plain water and mild soap to remove dirt and environmental buildup
- Consider moving painting out of direct sun or rain exposure to prolong its life
With proper sealing and care, an outdoor acrylic mural can look fantastic for many years before needing restoration.
Common Questions
What sheen of varnish should I use?
A satin or matte varnish provides adequate UV protection while minimizing glare and fingerprints. Glossy finishes make weathering and yellowing more visibly apparent over time.
How many coats of sealant should I apply?
2-4 thin coats are recommended, with thorough drying between coats. Very porous surfaces may need additional coats. Too many thick coats can cause cracking or yellowing.
What kind of paint markers work best for touch ups?
Oil-based paint markers formulated for outdoor use work well for small touch ups. Make sure to re-seal markings for protection.
How do I get rid of mildew on an outdoor acrylic painting?
Gently wash with a mild bleach solution (1 part bleach, 9 parts water), rinse thoroughly, allow to fully dry, then reseal affected areas.
Can I use automobile clear coat on acrylic paintings?
Yes, though the spraying process requires safety gear. Many artists reserve auto clear coats for very large murals and follow all label precautions.
Final Thoughts
Perfectly sealing and maintaining your outdoor acrylic masterpiece may seem daunting, but just follow the process:
- Use quality exterior-rated paints and surface prep properly
- Apply paint in thin layers under optimal conditions
- Allow the recommended curing time before sealing
- Apply thin, even coats of UV-resistant acrylic varnish or epoxy
- Wash, recoat sealant, and spot fix as needed over time
With the right materials and techniques, you can keep your outdoor acrylic painting looking vibrant for many years of enjoyment. Just be patient during the process and do each step thoroughly. Let your art make a lasting impression!