FAQ: COR-TEN Weathering Steel and the Purpose of Patina

Welcome back to our FAQ series.

We started this FAQ series because we noticed that we often received the same questions over and over again. Since we want to serve you well, we decided to start an FAQ series to make information about our planters and other products more accessible. 

Today, we are addressing the question, "Some of the product descriptions say that the product will patina. What does this mean?"

We understand that when you buy a product you want to make sure that it is high-quality and long-lasting. So, understandably, products with the word "patina" in the description should be clearly defined. 

Any mention of patina is usually in reference to our products made of COR-TEN weathering steel. Patina is an important process for COR-TEN. COR-TEN is actually named for two of its properties corrosion resistance (COR) and tensile strength (TEN).  

COR-TEN Weathering Steel before patina occurs

For COR-TEN to become fully corrosion-resistant, it needs to go through a patina process. During this process the steel changes from a raw metal look (in which the color of the steel is gray seen in image above) to patina (where the metal turns the color of orange-brown).

To patina, the planter does need to be placed in the elements. This means that COR-TEN weathering steel should only be used outdoors and planter should not be covered. It is important to note that when the planter is going through the patina process, the metal can bleed onto the surrounding surface. 

Once this change has occurred, the weathering process of COR-TEN is complete. This means that the steel is now resistant to corrosion and is perfect for many outdoor climates. (Note: COR-TEN weathering steel planters need to be at least two kilometers away from large bodies of saltwater, as saltwater can erode this material. I.e., you wouldn’t want to use COR-TEN in a cafe located next to a saltwater beach).

Powder-coated aluminum in weathered rust. A terrific alternative to COR-TEN weathering steel. 

If you love the look of COR-TEN weathering steel but do not think the material will work for your needs, we recommend using powder-coated aluminum planters in weathered rust. This is a commercial alternative that mimics the look of COR-TEN weathering steel. 

Call us at (866) 538-5001 to talk about your using COR-TEN weathering steel planters—or an alternative—in your next project. 

Shop PureModern COR-TEN weathering steel planters.