Urethane over Enamel – Can Something Go Wrong?

Wood surfaces are a beautiful alternative. They are durable and require little upkeep. Plus, they offer the same warm feel of traditional wood surfaces that many people love. The problem is that wood surfaces can only be made with urethane over enamel because it is a porous surface (not to mention the lack of availability of natural materials).

Urethane and enamel have their drawbacks. Urethane is a volatile synthetic, meaning it can explode when they are exposed to heat, such as the temperature generated by electricity. It also produces harmful fumes when applied to certain materials such as certain metals and it rubs off easily and can be ingested or absorbed through the skin. To top all of that off, the urethane will not adhere to porous surfaces such as wood or stone.

One way to avoid these shortcomings would be to have a one-size fits all material. A porous surface, naturally dry and soft, but has the resistance of enamel.


Urethanes are a class of polymers that contain the functional group isocyanate. These types of polymers are widely used in many applications today. Urethanes are used in many products from propellants to industrial coatings. It has been in use since the 1930s and was widely used during World War II.

When urethane is applied and cured, it produces a water-resistant coating that is also resistant to weathering and abrasions.

It is mostly used for coating glass or flat surfaces. However, urethane has also been used in many other applications such as adhesives, sealants, and caulks.


Enamels are a class of organic chemicals that can be described as the organic version of lacquers. The most common form is enamel which is found on human teeth. Enamels are made by mixing pigments and solvents with a substrate such as alginate, acrylics, or polyester resin blended with glass powder.

Different pigments can be mixed together to create a multitude of colors. Enamels can also be formulated with other chemicals such as metals, boron nitrate, dyes, and fillers.

Enamels are used in many forms from plastics to metal. Enamel would make an ideal alternative to urethane because it has similar characteristics to urethane but is a natural material that is completely non-explosive.

Enamel Paint vs Urethane

Here are the differences:

  1. Strength and Durability – Urethane is more durable and stronger than enamel paints. Enamel paints should be avoided in areas with high impact to avoid chipping and peeling. In metal, urethane can remain stable for long-term use.
  2. Paint Color – Enamel paints have a wider range of colors. Urethane paint doesn’t. You can mix enamel to get a unique combination of colors. Urethane is a clear finish.
  3. Moisture Resistance – Both enamel and urethane are moisture resistant. However, the enamel is more water resistant than urethane. Urethane has been known to fall apart when it gets wet and, in some cases, can be chipped off the surface.
  4. Wood Protection – they are both durable on wood surfaces. However, urethane has been known to chip and tear the wood.
  5. Mold and mildew resistance – they both resist mold and mildew but urethane is better at doing it than enamel paints. Enamel paints are susceptible to mold and mildew, as with most paints.

Applying Urethane over Enamel Paint

Urethane is a clear paint, so it’s impossible to add pigment to it. Enamel paint can be applied over urethane by first, applying enamel paint and thoroughly curing. The second step is to apply urethane as a clear coat. This way, the enamel will act as a primer for the urethane, thus preventing chipping and peeling of the surface.

Enamel paints are more resistant to water than urethanes and are easily available in most hardware stores. Urethane finishes are mostly sold in paint stores, although there are some specialty paint stores that can help you choose the right product and application techniques.

Urethane offers a good alternative to enamel paints with its water resistance and longevity. That being said, it still may not be the best choice for wood surfaces. Urethane is more sensitive to moisture than enamel paints, and it’s more prone to chipping and peeling off than most other types of wood coatings.

What can happen if you mix enamel paint with urethane?

The two are directly incompatible because they chemically clash with each other. Enamel is a water-resistant coating that is vulnerable to heat and abrasions that are best applied to surfaces such as glass and metal. Urethanes are clear, durable, and unaffected by heat or abrasion which makes them ideal for wood surfaces. Enamel paints are best suited for metal surfaces because it is harder to chip and peel off than polyurethanes.

When you get them mixed, you will get a mixture that resembles mud. When dried and applied, the surface may appear smooth but will produce a splotchy finish because the urethane will not dry completely. You can scrape off the paint using a razor blade. This is because, one of the ingredients in enamel paint absorbs urethane, which chemically prevents it from drying properly.

Can you use mix-based urethane and oil-based enamel paint?

Mix-based urethane and oil-based enamel paints are different and incompatible. You should apply them separately to avoid ruining the finish. However, many builders and DIYers prefer to mix them together, because it can give the painting a more durable finish. This is because the oils in oil-based enamel paint prevent polyurethane from drying properly by absorbing moisture into it.

Why use urethane as a finishing coat?

Urethane is a better option than enamel, because it doesn’t chip or peel off and most importantly, it is a non-explosive, flexible finish that meets all the requirements of enamel paint. It not only protects the wood but also prevents moisture from reaching the wood. Urethane is also resistant to heat and abrasion, but since it is less durable than enamel paints it is best applied to surfaces that are subject to such conditions.


Mixing the urethane and enamel paint will never give you the desired results. In the long run, it will damage the piece and may cause deformation of the finish, loss of pigment, and eventually, chipping and peeling. So, when you’re painting, applying urethane as a clear coat over enamel paint is a better option because it offers a better-quality finish that can be applied to different surfaces such as wood or metal.