Steps for Perfect Polyurea

Polyurea is a specialized spray-applied plastic coating that requires unique equipment and training to apply. This article focuses on the preparation necessary for using polyurea in pond construction. However, it is important to note that as a pond builder, you are unlikely to apply polyurea yourself due to the significant investment and training required.

The equipment and training for polyurea application typically cost between $100,000 to $150,000 or even more. In order to see a return on this investment, it is crucial to operate the equipment properly and maintain it regularly. Allowing the equipment to sit idle for extended periods of time can be costly.

Polyurea is a two-part system that is heated to approximately 200 degrees Fahrenheit and 2,000 psi before being applied to the surface to be coated. A specialized set of pumping equipment, heated hoses, and a spray gun are used to apply the polyurea. The two parts, polyurea solids and isocyanate, are heated and mixed together by the pumping system, and then sprayed onto the surface through heated hoses that can be several hundred feet long.

There are various polyurea formulas available on the market for different applications, such as truck bed liners, roof coatings, decking, blast defense and armor plating, waterproofing, water containment, and structural protection. Many of these formulas contain specific chemistry, including plasticizers, to suit their intended application. However, formulas used for water containment typically consist of pure polyurea without any plasticizers.

The versatility of polyurea makes it ideal for pond construction, as it can be applied over almost any shape or structure without wrinkles or folds. It also has an elasticity of approximately 400 percent, allowing it to withstand the weight of boulders without leaking and preventing roots from growing through. When applying polyurea over bare dirt, an underlayment is first laid down before the polyurea is applied. Polyurea is also a suitable surface coating for cold joints in concrete and other structural elements like piers or islands. It is commonly used for indoor water features and features that incorporate the structure of a building.

It is important to note that polyurea is not adhesive. It adheres to most surfaces without the need for glue, but it must be mechanically secured to all penetrations, similar to using an EPDM liner. Pond-type skimmers, bottom drains, mid-water drains, and returns typically have clamping flange faces for liners, which are also suitable for polyurea. Top edges of the polyurea can overlap and be caught by the top cap or stone, similar to liner installations. Edge treatments can be achieved with a ledge around the top, utilizing stacked rocks and stones to hide and protect the edge.

Very few materials stick to polyurea, so when applying tile or vertical stone up the face of a surface or wall, a stainless-steel lath is typically bonded to the face to provide a grid surface for the mortar to bond to.

When considering polyurea for pond construction, it is important to think and plan around the requirements of the applicator to achieve the desired outcome. Creating a polyurea-friendly design and layout is crucial. Corners should be rounded rather than sharp, 90-degree shapes, as shooting into sharp corners can be challenging. Penetrations should be positioned at least 10 to 12 inches away from corners, floors, or other structures, allowing enough space for the spray gun assembly to maneuver. Columns and structures should be at least 18 inches apart, and shallow troughs should be at least 18 inches wide for proper clearance. If a deep trough is created, it should be even wider to ensure proper equipment control.

Polyurea is typically applied in multiple passes to achieve a thickness of around 80 mils. The spray gun should be held at a 90-degree angle to the surface, spraying head-on rather than at an angle, to ensure an even coat. Spraying at an angle can result in runs, leaks, and an uneven coating.

When applying polyurea over concrete surfaces, it is important to prepare the surface properly. The concrete surface should be troweled as smooth as possible or parge-coated later to fill any holes, gaps, or imperfections. Polyurea will mimic the surface it is applied to, so it is important to make the surface look good, similar to applying bodywork on a car before painting. It is recommended to use a parge coating system that becomes extremely hard and not grainy or weak when applied thin. Some parge coatings can have a negative reaction with polyurea and result in pinholes, requiring additional time and effort to rectify. It is advisable to consult with the chosen polyurea applicator before using any parge coating system.

The flanged surfaces of penetrations, such as skimmers or drains, will have multiple screw holes that will need to be located later to attach the clamp ring. It is recommended to