Moisture is among the greatest enemies of a quality surface preparation project. At its worst, it can cause you and your team to waste precious time and resources as you work to undo the damage done. What’s worse, left unchecked, coating pitfalls from moisture may make for some unhappy property owners and lost customers. 

At Runyon Surface Prep, we offer a wide catalog of concrete surface prep tools, machinery, and accessories for sale or rent. We’ve put together this post to help you understand the various ways moisture may affect your job and give you a few tips on how to prevent it.

The Effects of Moisture on Surface Coating

Knowing the potential effects of moisture on your coat will help you be more diligent in combating surface prep disasters and ensuring a good quality finish. While moisture on surfaces, in the air, and in your machinery may lead to a plethora of issues, we’ve highlighted the more common issues caused by moisture: 

Poor Adhesion Caused by Flash Rust

Flash rust occurs when moisture gets into your surface prior to the application of the first surface coat. When this happens, the coat fails to adhere properly, and the coating fails. Note that you may not even realize you have an adhesion issue until it’s too late and you’ve begun your second coat. So, it’s important to be diligent about keeping your surface dry before the first application.


Delamination may occur if there is significant humidity enhancing condensation or moisture on your surface. Delamination is the fracturing of a coat into layers. Delamination can make your coating job appear, cratered, ugly, and even incomplete.  

Blistering or Blooming

If you’ve ever seen what looks like out-of-place pores or bubbles on a finished surface, you’ve seen a floor blistering from a moisture-compromised coat. That’s because too much condensation on the surface prior to coating causes blistering. There’s no getting around blistering without first taking steps to prevent it. One way or another, the water under a layer of coating—as it evaporates—will get out and it will leave a constellation of nasty blisters all over your once-beautiful floor.

Preventing and Removing Moisture Before It Becomes a Problem

There are times when the moisture is easy to spot and remove – some droplets along the surface or an obvious humidity in the air. But there are also times when the moisture isn’t so obvious. When working with concrete, for example, there may be moisture underneath that is not visible to the human eye or when you graze the surface with your fingertips. Take note of the following ways you may combat moisture and prevent it from causing issues down the road:


If you’re looking for a simple and efficient means of removing moisture, dehumidifying the space, as well as the air inside a blaster’s tank, will help to prevent serious issues. Dehumidifying prior to coating may not only prevent blistering and poor adhesion but may also increase the longevity of your final polished coat.


Testing the surface is another way to ensure the prevention of moisture-related pitfalls. This can be done with a concrete testing device or by sealing a sheet of plastic over the concrete surface and leaving it there overnight. When you return to your plastic sheet, remove it and check to see if moisture has collected.

Sweep, Scrub, Mop, Dry

First and foremost, how thorough are you in preparing your surface for coating? While dehumidification and testing can certainly help in hard-to-tell situations, performing your due diligence in general cleaning prior to coating is of utmost importance for the quality of your coat. Your concrete coating can only do so much if you’re not making genuine efforts to keep the surface clean.  

Runyon Surface Prep – Full-Service Sales and Rental Facility  

From technical training to equipment rental and sales, we offer a wide range of products and services for your concrete surface prep needs. Know that we’re not only in the business of boosting your project’s quality, but we’re also dedicated to building long-lasting partnerships. When you come to us, you get more than a simple transaction. New to the industry or looking to expand? Runyon is here for you every step of the way. Whatever your experience level, learn more about how we can help by giving us a call or filling out our online form.