VOC Trends Continue to move levels lower

When using oil based steel primer, temperature at the time of coating is important. Paint will dry at a slower rate in colder temperatures and its drying solvents can evaporate away before drying is complete, leaving a clay-like film in its place. This is called 'cold curing'.

Environmental regulations for the construction industry are continually developed, and in many cases increased. As most readers of this blog are likely already aware, one highly regulated area of construction pertains to the use of steel primers, particularly the level of volatile organic compounds (or “VOCs”) that they contain.

Paint and Coatings are a universe of options and complexities. Fortunately for the steel fabricator the scope is limited by the requirements. Priming forms the basis of the coating system and often that is the only coat the steel will receive. Most of our customers prime steel in red or gray. Some of the miscellaneous and ornamental fabricators choose black. A few, for marketing purposes, choose their own color, such as green or blue to stand out on a job-site so anyone seeing the steel knows it was their work. Regardless of the color the basic primer has one function. Prohibit rust until the structure is enclosed.

There are an unlimited number of brands and types of Shop Coat Primer for the Steel Fabricator to choose from. Levels of quality vary greatly and different systems can be called out on shop drawings. They will range from the basic Red Oxide or Gray shop coat, with no additional requirements to the more complex and much more expensive 2-part systems, High Solids Rust Inhibitives and Universal Primers.

Fabricated steel is usually primed in the shop and at times requires welding in the field. Most alkyd (oil) based primers will burn away immediately and turn to dust. This leaves the weld and weld area without any corrosion protection. Often, it will begin rusting within days. There are a number of factors that cause weld material to rust. For a better understanding of what causes Weldment Corrosion ASM offers an in-depth review “Basic Understanding of Weld Corrosion.” (click)