Considerations To Make When Painting High Performance Sealants

 

Now, let’s take a look at the paint-ability of certain high performance sealants based on their technologies:

Polyurethanes:

High performance polyurethane sealants provide a tenacious bond with great tear resistance while maintaining elastic properties. Once cured, these sealants can be painted with high quality acrylic latex paints.

•  What to Keep in Mind When Painting High Performance Polyurethane Sealants

It is recommended that a high performance polyurethane sealants cure for at least three days prior to painting.

Additionally, these sealants are moisture reactive. As a result, it’s important to not introduce copious amounts of water (from the paint). Doing so can cause these sealants to “flash cure”, which increases the potential for surface bubbling.

If using an older high performance polyurethane sealant, a thorough solvent wipe down should be performed to remove any dirt, chalking or surface contaminants.

Bostik 915 is an example of a high performance polyurethane sealant. The first and only product on the market, 915 is Miami-Dade Country Product Control Approved as a roofing sealant and roof tile adhesive. It also has adhesion to Kynar® resin-based coatings and a best-in-class warranty.

Hybrids:

Hybrids are a general category of high performance sealants and are comprised of technologies including Silyl Modified Polymer (SMP), Silylated Polyether (SPE) and Silylated Polyurethane (SPUR). Like high performance polyurethane sealants, using high quality acrylic latex paints offer the best results.

• What to Keep in Mind When Painting High Performance Hybrid Sealants

High performance hybrid sealants do not require as much cure time as polyurethane sealants. This aspect allows contractors to complete their work sooner. However, it is important to first allow a good skin to develop prior to painting. This skin prevents deformation in the sealant joint surface.

Bostik Pro-MS 50 is a high performance hybrid sealant. Ideal for windows, doors, facades and siding, this product has adhesion to Kynar resin-based coatings and AAMA certification.

Silicone:

High performance silicone sealants are more difficult to paint and are considered slippery. Traditionally, paint does not perform well over the long term as a result.

While these high performance silicone sealants are marketed as “paintable”, it’s important to note that performance comprises may occur vs. polyurethane and hybrid sealants. As a result, it’s recommended to fully review and understand performance requirements prior to choosing whether or not to paint.

Bostik manufactures 1200, a high performance silicone sealant that offers superior adhesion to substrates such as glass, metals, ceramics and most plastics. It has excellent weathering properties and can withstand the harshest atmospheric conditions.

Construction is one of the largest market areas for sealants. According to Markets and Markets, the construction sealant market is expected to be worth $8.93 billion by 2020. With applications ranging from foundation walls to roofs, sealants are needed throughout residential and commercial building projects.

These sealants must offer flexibility, temperature stability, weather resistance and chemical flexibility. High performance sealants in particular offer additional properties such as:

• Meeting or exceeding industry specifications/accreditations
• Lower volatile organic compounds (VOCs)
• Greater elastic bonding capabilities
• High elastomeric properties

However, these high performance sealants do not come in a variety of colors and often need to be painted to match surrounding areas. Let’s take a look at general considerations to make when painting high performance sealants.

Dynamic Movement 

Paint typically cannot withstand high performance sealants’ dynamic movement and may crack or peel. It’s important to know the anticipated movement ahead of time. Then, the paint manufacturer can be consulted to determine the ability of the paint to accommodate the movement.

Staining 

In some cases, a stain application may be needed or desired. High performance sealants do not possess the same surface porosity as the adjoining wood, for example. As a result, the sealant may not be able to perform to the desired outcome.

For example, if attempting to stain wood, the sealant is unable to absorb the stain in the same manner. This increases possibility of different shades of stained surfaces. Ensure that the customer fully understands the sealant performance expectations prior to staining and will be satisfied with the overall aesthetic look.

Chemical Compatibility 

It’s recommended that the chemical compatibility between the paint and sealant is verified prior to painting. This means understanding whether or not the paint dries or cures once applied to the sealant. While it appears dry or cured, a surface tack can sometimes develop on the paint surface. There may be no evidence of paint transfer; however, a tacky surface can increase the likelihood of dirt pick up.

This tackiness can be from a variety of causes, which is why Bostik recommends a jobsite adhesion test prior to starting the project. This test captures any site-specific anomalies that could impact the final outcome.

For more information on smart high performance sealants, call 800-7-BOSTIK, or visit www.bostik-sealants.com.