Baked Enamel: What’s the Deal?

Thu, 2011-07-28

From the car you drive every day to the stove in your kitchen, thousands of products with metal surfaces use enamel coating.  It helps preserve color and prevent rusting and, of course, is used on steel and aluminum industrial safety signs

This article explains why Stonehouse prefers to use polyester baked enamel finish with thermo-setting inks for the majority of our customers.

Stonehouse Baked Enamel Safety Signs last longer than a standard aluminum sign.Beware the Sun

The enemy of all organic coatings is UV radiation.  A sign installed outdoors, regardless of the type of coating, substrate, or ink that is used, will weather in the sun.  UV rays from the sun will eventually break down the binders that hold the pigments (colors) to the sign, which causes the sign to weather. 

One property a sign maker can control through careful coating selection is UV resistance. In other words, how quickly (or slowly) the binders’ polymer bonds are broken.  If UV resistance is of primary concern, then the quality of the coatings determine the life of the sign.

That’s where a baked enamel finish comes into play.  When you apply heat to baking enamels, a reaction (called cross-linking) takes place that causes the polymers to form a stronger chemical bond than would otherwise be achieved.  Remember those binders- their job it is to hang onto the pigment.  Ours hang on longer because their bonds are stronger. That’s the beauty of baked enamel!

The cured film of a Stonehouse baked enamel sign, married with a compatible thermo-setting ink system, produces unique outdoor properties that other signs just don’t have. 

Choose Your Properties Carefully…

Any outdoor sign will be subjected to the elements. After Mother Nature has had her way with the sign, it will be scraped, scratched, scuffed, vandalized and abused (I can’t think of one kid that hasn’t thrown a rock at a sign or two). 

What properties are most desirable for signs, considering the numerous coatings that are available today? Aside from adhesion and UV resistance, two basic requirements for all outdoor signs, the following properties should be considered:

  1. Hardness/Abrasion resistance – How easily does the coating scratch/scuff?
  2. Impact Resistance – What happens when the coating is struck by an object such as a heavy, metal dart?
  3. Flexibility – How far will the coating stretch (elongate) without cracking?

In most cases you will give up flexibility for hardness and vice versa.  However, baked enamels provide the best combination of hardness, flexibility and impact resistance, producing a high quality, durable sign that will look pristine for many years to come.

Why Does Stonehouse Use Baked Enamel for Aluminum & Steel signs?

It’s simple… we have tested many different coatings in our 148 year history.  Over time and through extensive testing, we have determined that polyester baked enamel provides the best possible coating for a long-lasting, durable outdoor sign. 

We think it’s so effective that we have been using baked enamels for 40+ years.  Want more information about which materials are best for your application?  Visit the materials section of our design guide for more information!

Stonehouse Signs offers a full line of standard industrial safety signs for every application.  Don't see what you need?  Create a 100% Custom Sign, or ask your account manager to Change It Up- make simple wording changes, add a standard pictogram, use ANSI headers, or even change the hazard level free of charge!

Learn about what elements affect how long your sign lasts outdoors in our next article- What is 'Outdoor Durable?' !