7 Benefits of Using a Urethane Hard Coat for EPS Theming

Using EPS foam to build props, statues, architectural forms, and more is becoming more and more prevalent. Applying a coating to protect the foam is now standard practice for the longevity of EPS theming projects. Though, it’s the type of coating you choose that matters.

Urethane hard coats are just one option for coating EPS, but they might be the best form of protection for your piece. The following blog breaks down the 7 benefits of using a urethane over EPS structures and why VFI recommends this material over every other.

1. Extremely Durable for Increased Longevity

Urethane is known for its exceptional durability. Because hard coats can be formulated to have a Shore hardness between 50-75 D, they have great resistance to wear and tear. They also have a bit of flex to help them endure temperature changes, making them capable of withstanding harsh conditions without cracking. Once cured, they are sealed and resistant to water, which is useful for protecting foam objects in outdoor environments where rain or other weather events are expected.

We expect that your EPS structure might endure heavy abuse from being touched, sat on, or climbed on by children and adults alike. Since these coatings are abrasion-resistant, they are applied thick enough to combat this type of wear to protect the foam underneath. This durability reduces the need for frequent repairs or replacement.

2. Specialized Fire-Retardant Versions for Indoor Use

EPS projects are great for both indoors and outdoors. However, if you’re working on an indoor project, you must adhere to strict building requirements, including fire safety regulations. That’s why there are hard coat formulas that contain fire retardants. The fire retardant makes them capable of meeting ASTM E84 Class A fire testing.

We know how important it is to have the ability to choose, so VFI has options that have been fire-tested and cost-effective formulas that don’t contain any fire retardant. VFI-2538 70 D Form Hard Coat is one of the coatings we offer that isn’t fire-tested. However, it provides a protective surface that is seamless and smooth with a reduced need for sanding after spraying.

3. Fast Setting for Increased Production

If project deadlines are crucial for your fabrication shop, you’ll want to work with a material that can be applied quickly and sets just as fast.

Urethane hard coats are quick-curing materials, regardless of the application method. Even brushable urethane coatings cure faster than other brush-on materials like epoxy. VFI’s coatings are ready to sand the same day because they harden quickly.

Sprayable coatings are great for working on large projects for this reason. They can be applied to vertical and horizontal surfaces without sag. Using a brushable coating is a little harder since the viscosity and gel time are slower, so they’re better for small projects and repairs.

Other materials that have been used a lot in the theming world, such as epoxy and fiberglass, take a lot of time to apply and cure. Epoxies are brushed or rolled due to the harmful compounds they release when atomized. Layering fiberglass with epoxy resin can take days to complete, whereas urethane hard coats will be ready to paint the same or next day.

Properties Showing Speed per Hard Coat Material
Property	VFI-6170	VFI-6171	VFI-2519	VFI-2626
Pot Life	N/A	N/A	15 minutes	15 minutes
Cure to Touch	20 seconds	80 seconds	N/A	N/A
Cure to Handle	2-3 minutes	5-7 minutes	N/A	N/A
Recoat Window	20 minutes	20 minutes	Less than 4 hours	Less than 4 hours

4. Lightweight for Large Projects

Using 1-3 PCF foam makes these structures lightweight compared to materials like wood, metal, concrete, etc. It especially comes in handy when you need your project to hang, which is sometimes required for projects like museum displays and signage.

The good news is that urethane is applied relatively thin and doesn’t add much more weight. Most coatings recommend 40-80 mils for a typical project or 60-120 mils for heavy-duty projects. Mils are extremely thin measurements defined as one-thousandth of an inch. The highest mil rate (120) we recommend is just under 1/8th of an inch. Brushable coatings will have a higher minimum thickness requirement of at least 60 mils, with 100 mils recommended for the best film properties. However, these coatings are used for small projects, so they will barely add weight.

5. Adapts to Surfaces and Contours without Diminishing Details

For theming and attractions, detail is an essential part of the project. Sprayable and brushable urethanes are great for covering difficult shapes, curves, and recesses prominent in figures, decorations, and art pieces. They have a nice flow, regardless of application format, and ensure your details aren’t diminished. Urethane also has excellent adhesion to these surfaces, making it great for various decorative EPS elements.

6. Easily Customizable for a Variety of Applications

You carve the EPS to meet your desired design, and the urethane just creates a neutral protective layer before you add the finishing details. It is sandable, so you can get rid of any imperfections on the surface and then paint it to make it stand out and come to life.

Whether you need to protect a small or large EPS structure, urethane comes in various formulas to fit your processing requirements. It can be tailored to meet the needs of each unique piece, whether you need a soft, cushy material or a hard, impact-resistant one. VFI can also offer alternative coatings for your unique projects.

7. 100% Solids for Environmental Safety and Material Savings

These coatings are 100% solids, which benefits the user in two ways. They don’t contain any harsh solvents that will evaporate and release volatile organic compounds as they cure. This also means that the amount of coating applied is the amount that will remain on the surface once cured. So, you don’t have to worry about buying and applying even more material.

How to Hard Coat & Finish a Foam Structure

Once your foam is carved or machined into the exact shape you want it to be and cleaned up, you’re ready to add a hard coat. There are several different methods of applying a hard coat. VFI’s urethane hard coats are usually applied by brush, high-pressure spray, or Qwik Spray.

• Brushable coatings: Use a foam brush, chip paint brush, or foam roller.
• High-pressure coatings: Use a high-pressure plural component system capable of meeting certain temperature and pressure requirements.
• Cartridge-based coatings: Use a pneumatic air-driven applicator and an air compressor capable of 10 cfm at 100 psi. We even have details on how to assemble and use the Qwik Spray System.

Once cured, the coating must be sanded to achieve a smooth look and for paint to adhere without a primer. Depending on the application method, you may have to sand the surface more to get rid of brush strokes or overspray. Note: Working on surfaces larger than 4 feet by 6 feet with Qwik Spray equipment will cause more overspray and it is harder to get a consistent finish.

Once you’ve achieved an acceptable surface, you can apply paint and other details. Automotive primers and paints are acceptable, as well as other architectural finishes. Please do your own testing to see what materials work best for your project.

Alternatives to Urethane Hard Coat

• Bedliner (polyurea hybrids). Some theming projects require a coating with a lower durometer for more flexibility and softness, like our polyurea hybrids offer. They provide the best balance of price and performance for outdoor or high-traffic theme park and attraction projects. They form a tough shield that keeps surfaces, including wood and metal, safe from impact, abrasion, and weather-related damage. Black is the standard color, but other color options can be purchased in Qwik Spray cartridges. To avoid sunlight degradation, they will require a UV-stable topcoat.
• Machinable Hard Coat. VFI recently added a harder coating to its theming line. This urethane coating is slightly harder than our typical hard coats and is almost concrete-like in appearance. It is troweled onto surfaces because of its high viscosity. Once applied, it can be CNC’d or machined for advanced shaping, fine detailing, and complex geometries. It can then be painted to meet a desired aesthetic. It also works great as a repair material.
• Sculpting Epoxy (FR). Also new to the VFI theming line is our sculpting epoxy. This is similar to the machinable hard coat in viscosity, but it is an epoxy. It’s also a trowel-applied product that can also be machined to achieve desirable shapes and designs. If you need a coating that you can sculpt and texturize a surface with, this material is great, especially since it has a pot life that lasts for several hours.

Contact VFI to find the best urethane hard coat for your EPS theming project.