Testing “Pre-Patina” Treatments for Weathering Steel

Testing “Pre-Patina” Treatments for Weathering Steel

Architects and builders often select weathering steel for its unpolished texture and orange-brown patina. However, this sought-after patina color develops over time as the steel is exposed to weather and various outdoor elements. In its original state, weathering steel is a bluish-silver color – just like standard steel. 

For reference, Atlanta Fine Gardens, a landscape company located in Atlanta, Georgia, recently used weathering steel to build a raised planter bed, stairs and railings in its customer’s backyard. The first photo captures how the weathering steel looked in its original state. The second photo on the right was taken three months after installation. You can also check out the patina process of our office building here

Weathering steel raised garden

Weathering steel raised garden

Over the years, we have had several customers inquire about ways to expedite the patina process or “pre-patina” weathering steel so that it develops the orange-brown patina color prior to installation. 

Ways to Pre-Patina Weathering Steel

We recently completed a little experiment to showcase two ways to “pre-patina” weathering steel. For the experiment, we used three ¼-inch hot-rolled weathering steel squares and treated each differently. 

On the first square, we applied water only to serve as the control variable. We applied a mixture of hydrogen peroxide, vinegar, and salt water on the second or middle square.  And on the third square, we applied muriatic acid. We applied five treatments in a span of 5 days to initiate the patina process. Check out the photos below to see firsthand how the steel weathered.

Weathering Steel after first treatment

Weathering Steel after second treatment

Weathering steel after third treatment

Weathering steel after fourth treatment

Weathering steel after fifth treatment

Based on the results, the muriatic acid should be used with caution. As you can see, it caused flaking and odd coloring. The hydrogen peroxide, vinegar and salt water mixture weathered more naturally. 

While we always recommend leaving weathering steel untreated to patina naturally over time, the hydrogen peroxide, vinegar and salt water mixture is the better option if you need to “pre-patina” the steel to prevent staining from run-off or for other reasons.  When the pre-patina finish is obtained, consider applying a clear coat sealant. 

Contact Central Steel Service

Do you have more questions about weathering steel? Contact one of our experienced sales associates. As a trusted supplier of weathering steel, we are committed to providing customers with an exceptional level of service and making your buying experience easy.