Issue 5: Surface and Substrate Preparation

Surface and Substrate Preparation

Having the correct Surface Preparation can be the difference between success and failure in Coating adhesion

Polyurea coating has been called a revolutionary chemistry that can be applied down to -35˚ F and withstand water exposure almost immediately. As good as the technology is, however, the truth is that no coating chemistry can make up for an improperly prepared surface. Ask anyone in the industry, and they’ll tell you that most failures are a direct result of poor surface preparation.

In fact, in its infancy, polyurea was promoted as the coating that would cure on any substrate.  But many early polyurea jobs failed because the coating cured without sticking to the substrate.  The result was a catastrophic adhesion failure for the job and a public relations problem for the polyurea industry. The performance properties of a coating system don’t eliminate the need for the user to ensure that the coating system has something structurally sound and clean to which to adhere.

If a surface is contaminated with oil, for example, the oil must be removed. The substrate must not only have a surface or anchor profile to get good mechanical adhesion, but also have a level of cleanliness appropriate to the application and end use. Beware of the salesperson who tries to convince you that the product is tough enough to make up for an inadequately prepared anchor profile.

Also known as surface profile, the anchor profile is the topography of the surface to be coated.  If the anchor profile left by the surface preparation is too smooth, it allows for coating slippage, or creep, when the coating is exposed to lateral pressure. So be sure that there is an appropriate level of roughness for the coating to fill. The level of anchor profile required depends on the coating system used, the choice of primers, and other considerations that the specifier should consider. The graphic visually demonstrates the anchor profile.

Ask questions and get answers that make sense ahead of time to avoid having to backpedal and investigate a job failure later. Polyurea coating technology is coating chemistry. Protect yourself with the facts. At the end of the day, you are the one to whom your customer will either give, or not give, repeat business and referrals. It’s your reputation on the line.

Leave a Reply

Your email address will not be published. Required fields are marked *