There are quite a few people who are unsure about the real purpose of the prime coat and tack coat. In fact, there are many people who believe that a prime coat is only designed to make the tack coat more adhesive and nothing more. A prime coat and a tack coat actually work much more like a preparation and a completion of the same project. Often, prime coat and tack coat discussions are centered around asphalt preparation, as these two layers are integral to the final asphalt performance.

What is a Prime Coat?

Some people believe that a prime coat is only designed to make the tack coat more adhesive and nothing more. A prime coat is a coating applied directly to a prepared base before additional layers of support or coating are supplied. Prime coat asphalt preparation is a vital element, as it directly affects the shear strength of the final asphalt product.

A prime coat is mainly responsible for protecting the substrate of a construction project before additional layers are added. In asphalt preparation, they can also act as a binder with secondary and tertiary compounds, creating a better adhesion between the layers. Prime coat asphalt acts as an initial sealer in the asphalt laying process to block the other layers from moisture, dust and debris before additional coating installations.

Important things to remember about installing a prime coat or prime coat asphalt are:

• It provides temporary waterproofing, but must have additional compound layers in order for the floor, wall, or ceiling coating to perform long-term waterproofing duties.
• The asphalt prime coat must completely penetrate the base surface in order to be effective.
• A prime coat must completely cure before an additional layer is incorporated.
• It is vital to be aware of weather conditions when apply an asphalt prime coat. In the case of wet weather, this step should be postponed to avoid runoff into the water supply.

What is a Tack Coat?

A tack coat is applied after the prime coat, to form an adhesive bond between the tack coat and the next layer of coating. The tack coat prevents slippage and may sometimes function as a more long-term sealer to protect the substrate from moisture and bacteria. For asphalt prime coat systems, the tack coat is one of the most vital parts of the process, as it connects the subsequent layers and forms the base of those layers’ strength.

Important things to remember about installing a tack coat are:

• It is vital that the prime coat is clean and dry before installing a tack coat.
• The higher the viscosity of the tack layer, the more shear strength the overall structure will have.
• Diluted, slow-set emulsions are the most typical style of applying a tack coat.

Prime Coat and Tack Coat Summary

When choosing a prime coat and tack coat, it is vital to understand the functions of each of these elements, as well as their limitations. With a good prime coat and tack coat, you can prepare your substrate for virtually any type of application, and be confident that the resulting floor, wall, or ceiling is strong and durable for years to come.