Survey markers come in a variety of shapes and sizes, but when long-term durability is the goal, a marker's composition is key.
Typically, survey markers are made of one of many brass or bronze alloys. Since the early 20th century, brass was favored by many manufacturers for being relatively inexpensive while still retaining strength and reliability. Since then, however, trends have changed significantly due to serious concerns over the safety and longevity of brass alloys.
Today, customers are increasingly turning to bronze for survey monuments and markers for several key reasons. Let's explore the differences between the two materials and why bronze has emerged as a far more popular choice for buyers looking for a safe and durable product.
Brass's potentially hazardous composition
The shift away from brass is due in part to health concerns surrounding the alloys commonly used in survey monument and marker manufacturing. Alloys with high lead content (over 5 percent) pose a serious health risk to those who come in contact with them, leading many to regard the alloy as outdated and archaic given today's standards.
Leaded Red Brass 85-5-5, containing five percent lead and Leaded Semi-Red Brass 81-7-9, containing seven percent lead are two alloys, in particular, which pose dangerously high lead content.
Unlike brass, bronze alloys contain no lead whatsoever, making them an obvious choice in just about any situation where people may come in contact with the marker or monument.
Brass alloys are more susceptible to corrosion
Brass is just one family of alloys in a much broader group of copper alloys. As such, the primary components of brass are copper and zinc, which vary in ratio depending on the particular kind of brass it is.
Because many brass alloys typically contain a significant amount of zinc, they're susceptible to "dezincification." This is a type of corrosion that weakens brass alloys as the zinc deposits deteriorate far faster than the other components, leaving a pinkish hue and a visibly distressed surface.
While studies have found that alloys with 15% or less zinc content are at less of a risk of corrosion, any zinc-bearing alloy can degrade in varying degrees. Over time, the damage this corrosion creates can challenge the integrity of the survey marker, shortening its lifespan considerably.
Although bronze is another kind of copper alloy, it typically has little to no zinc content, making it virtually impervious to dezincification.
High-quality bronze alloys offer greater strength and durability
After years of experimenting with various non-leaded brass and bronze alloys for survey monuments and markers years ago, Berntsen concluded that alloys high in copper provided the best corrosion resistance, strength, and durability.
Today, we exclusively use a silicon bronze alloy for all of our cold forged survey markers and caps. After rigorous testing in an independently conducted assessment, this 97 percent copper, 3 percent silicon alloy was found to have essentially no corrosion after 200 hours of exposure to a salt spray.
Although brass offers a slightly less expensive alternative, investing in a high-resistance bronze ensures your survey markers will resist even the most punishing conditions for far longer than a brass product is capable of. This is especially true in environments where exposure to water is a factor.
Want to learn more about our line of high-quality bronze survey markers? Click here to browse our inventory or request a catalog today.