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Key Takeaways
- Aluminum is lightweight and corrosion-resistant, making it ideal for outdoor signs.
- Stainless steel is stronger and more durable, perfect for high-traffic or premium signs.
- Aluminum has a better strength-to-weight ratio, while stainless steel offers a polished finish.
Metal signs make a powerful statement, combining durability, versatility, and a polished appearance that elevates any business’s professional image.
At ShieldCo, we believe that the material behind your custom logo or business sign is just as important as its design. The right choice ensures your sign not only looks exceptional but stands up to the elements over time. Aluminum and stainless steel are two of the top materials we recommend for their unique strengths. The table below breaks down their key differences, helping you select the best option for your custom metal sign
Aluminum vs Stainless Steel: Which is Best for Your Metal Sign?
| Property | Aluminum | Stainless Steel |
|---|---|---|
| Weight | ~1/3 the weight of stainless steel; lightweight | Heavier, requiring more support for large signs |
| Strength | Lower tensile and shear strength but sufficient for signage | Higher tensile and shear strength; more durable |
| Strength-to-Weight | Better strength-to-weight ratio (~99) | Lower strength-to-weight ratio (~63) |
| Corrosion Resistance | Naturally resistant; marine-grade alloys (5052) are highly resistant | Chromium provides resistance; 316 alloy offers superior durability |
| Cost | Higher cost by weight but lower by volume | ~30% more expensive by volume than aluminum |
| Malleability | Highly malleable, easier for intricate designs | Less malleable; retains shape better |
| Electrical Conductivity | Good conductor; often used in electrical applications | Poor electrical conductivity |
| Welding | More challenging but possible with proper equipment and care | Easier to weld with a variety of gas mixtures |
| Maintenance | Minimal with powder coating; outdoor signs may oxidize | May require cleaning to prevent minor rusting |
| Best Use Cases | Lightweight outdoor signs, intricate designs, marine environments | High-traffic areas, premium indoor signs, polished finishes |
Aluminum vs Stainless Steel
weight
Aluminum is about 1/3rd the weight of stainless steel (and steel for that matter). Aluminum is much much lighter! A 4ft by 4ft sign in our multiple layer format could weigh 40lbs. This is without a doubt light enough to hang directly on drywall with standard wall anchors. If the same sign were made out of all stainless steel, the weight would be 120lbs and would require reinforcement behind the drywall.
Strength
The strength of metals can be measured in a few different ways and they are all related to how different loads can be applied to an item. Two of the most common ways are tensile strength and shear strength.
Tensile strength - Tensile strength is the amount of load or stress that can be handled by a material before it stretches and breaks. Think about having a hole in the material and then hanging weight from it. This is often represented with PSI. Your standard alloy of aluminum would be rated at 40,000 PSI. Stainless Steel would be 70,000 PSI.
Shear strength - Shear strength is its ability to resist forces that cause the material's internal structure to slide against itself. Think about having a bolt fixed in a horizontal position, and a weight hanging from that bolt immediately after the fixed position. At a certain weight, the bolt is going to fail and the weight is going to move. For aluminum this is 30,000 PSI and stainless it is around 50,000 PSI.
What does this mean for signage? Well, aluminum is plenty strong to be used for signage, particularly if it is layered. If the sign was a single layer and strength was a major concern, then stainless steel could be the better option.
Strength to weight ratio
(Force per unit area divided by density)
Aluminum has a tensile strength of 276 MPa and a density of 2.81gcm-3. Therefore it’s strength to weight ratio is ~99.
Stainless steel has a tensile strength of 505 MPa and a density of 8 gcm-3. Therefore it’s strength to weight ratio is ~63.
From a strength to weight perspective, aluminum is stronger than stainless steel. That is to say for the increase in weight from aluminum to stainless steel, you get less than a corresponding increase in strength.
Corrosion
Aluminum creates a passivation layer that helps it resist oxidation and corrosion. Aluminum comes in multiple different alloys with the bulk of all aluminum being 5052 and 6061. 5052 is considered marine grade and is more resistant to corrosion than 6061. Most of your “extrusions” are made of 6061. If aluminum is left outside it will begin to get a milky oxidation on the face of it quickly. If it is powder coated, the aluminum is protected from the atmosphere and won’t corrode which will leave the powder coat in tack for decades. Brushed aluminum on the interior of a building will retain its shiny look.
Stainless steel contains chromium which has corrosion resistance properties. Stainless also comes in different alloys, with the bulk of all stainless being 304 and 316. 304 is the most common type of stainless steel. 316 has a greater resistance to corrosion. 316 costs costs more than 304, but it will last longer and rust less.
Typically if you are making something out of stainless it is because you want the look of shiny metal and therefore you don’t typically powder coat stainless steel unless you are extremely concerned over corrosion, then 316 stainless steel powder coated is going to be your absolute best bet.
Cost
Aluminum is more expensive than stainless steel, when you compare it by weight. However, aluminum is about 1/3rd the weight of stainless steel, and when you compare the cost of the same volume of material, stainless steel is much more expensive, usually by about 30%
Malleability
5052 aluminum is very malleable. 6061 is likely to crack if bent. Aluminum has a lower tensile and shear strength than stainless steel and therefore is more likely to bend.
Stainless steel is more likely to keep it’s shape than aluminum,
Electrical Conductivity
Aluminum conducts electricity well. You can often find large scale electrical wires made of aluminum as aluminum is much cheaper than copper and the conductivity is similar (but less).
Stainless Steel is one of the poorest conductors of electricity amongst all the metals.
Welding
Aluminum is more difficult to weld than stainless steel, but with the advent of welding machines that can MIG weld aluminum, welding aluminum has become much easier. However, since the material is “soft” (when compared to stainless steel) you must be very careful when welding thin aluminum to not burn through it. When choosing an aluminum to weld, choose 5052, it is easier to weld than 6061. Use 100% argon shielding gas when welding aluminum.
Stainless steel is less difficult to weld than aluminum and you can also use a 100% argon shielding gas. However many welders will also use a mixed gas of 75% argon and 25% carbon dioxide.
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What does this mean for you?
Aluminum is a better metal to use for outdoor signs because it has better weather resistance than stainless steel. Stainless steel, however, has superior strength. Both metals can be used for indoor signs.
Essentially, the choice you make depends on what you’re willing to live with. Both metals will give you the refined look you desire. Their strength and weather resistance are the ultimate decision factors.
Our recommendation is always for aluminum since the weight is so much lower it make handling much easier!
Can I combine aluminum and stainless steel in one sign design?
Yes, combining aluminum and stainless steel can create a unique aesthetic and optimize for both lightweight and strength, depending on the design and functional needs.
How does the finish of aluminum compare to stainless steel for aesthetic purposes?
Aluminum can be brushed, polished, or powder-coated for a variety of finishes, while stainless steel offers a naturally shiny appearance and is ideal for a polished, high-end look without additional coating.
What maintenance is required for aluminum vs stainless steel signs?
Aluminum signs with a powder coat require minimal maintenance and resist corrosion well. Stainless steel signs may need periodic cleaning to maintain their shine and prevent minor rusting in certain environments.
Which material is better for intricate logo designs or cutouts?
Aluminum is generally better for intricate designs due to its malleability and lighter weight, which allows for easier cutting and handling during production.
How do aluminum and stainless steel perform in coastal or marine environments?
Marine-grade aluminum (5052 alloy) is highly resistant to saltwater corrosion, making it ideal for coastal areas. Stainless steel 316 also resists corrosion in marine environments but is heavier and more expensive.
Can aluminum and stainless steel signs be recycled after use?
Yes, both aluminum and stainless steel are fully recyclable materials, making them environmentally friendly options for signage. Aluminum is often more energy-efficient to recycle.
