Spraying Elastomerics and Roof Coatings – A Complete Guide
Elastomeric roof coatings serve to protect the underlying roof from rain, sun, and more. To provide this protection roof coatings are typically a thicker material and are often applied in thick coats. The thickness of elastomeric coatings creates unique challenges in applying them. In this guide we will cover what you should know when considering spraying elastomeric roof coatings.
Important Considerations when Spraying Elastomeric Roof Coatings
Due to the thickness of elastomeric roof coatings you typically need a large airless sprayer in order to be able to spray them efficiently. If you are just starting to consider spraying elastomeric coatings, you will want to review the tip sizes that are suggested for the specific elastomeric coating you intent to spray, in general most elastomeric roof coatings will need at least a 21 thousands tip opening for smooth elastomerics but can require as large as a 45 thousands tip, more on airless sprayer tips here. Knowing what your elastomeric coating will require for an airless sprayer tip size is critical because it will allow you to select an airless sprayer that is large enough to be able to spray your material, if you order too small of a pump it will not be able to deliver enough coating to your airless tip and will not be able to spray your material. In addition to the size of the airless pump, you will need for your elastomeric coating the other important consideration is the distance you will potentially need to run an airless hose. If you plan on doing large roof projects that will require a lot of hose you will want to consider a higher pressure ratio airless pump, especially if you plan on delivering material up a lot of vertical height because as you increase hose length and/or vertical height that you will deliver the elastomeric coating over, you will lose pressure in the airless sprayer line. This loss in pressure can create problems atomizing the elastomeric coating with your airless spray gun. If you will only be using 50 or at most 100 feet of airless hose for your project a 30:1 ratio airless pump should typically be sufficient but if your running more than 100 feet of hose or are using an elastomeric that will require a 40 thousand or higher tip size, you will typically want to consider a higher ratio pump like a 45:1 ratio airless pump or higher. If you decide you need a higher ratio airless pump to spray your elastomeric coating or a larger tip size (40 thousands or more) you should consider using an airless sprayer that is hydraulically driven. A hydraulic driven airless like the Graco 733 will have a smoother stroke and is able to pump material more efficiently than a standard gas driven airless sprayer. If your elastomeric roof coating requires a tip of 40 thousands or higher, you may need a direct immersion style airless sprayer, like the Graco 733 or something similar. A direct immersion airless sprayer utilizes a wider opening throughout the fluid section and directly draws material into the pump allowing it to pick up thick material much easier and with greater efficiency than a traditional gas or electric airless sprayer. Finally, when spraying elastomeric coatings you will want to ensure you have applied a sufficient amount of the material, elastomeric coatings have required thicknesses to ensure they perform properly. Verifying the thickness applied can be done with a mil gauge. In addition to applying a thick enough coat, if your spraying an elastomeric roof coating you will want to backroll after it is applied because this will help the coating bind to the surface more effectively.
With all this information it can seem a bit overwhelming so we have simplified the airless sprayers that will usually make sense based on the tip size your elastomeric coating recommends before making a decision though you will want to verify via your technical data sheet for your coating or by chatting with us.
Tip size 0.019 – 0.027
For airless tips in this size range you will be best to consider a pump that is able to support of about 1.5 Gallons per minute of flow the models below would be well suited for this task.
50 feet of hose or less 100 Feet of Hose or More
Tip size of 0.027 and Up
Generally you will need to consider a hydraulic airless at this tip size and ideally a direction immersion design to ensure you can deliver the elastomeric coating well as this will be highly viscous material.
Ultimately elastomeric coatings are unique to apply. You will want to ensure you select an airless sprayer that is sufficient to handle the job and ensure you follow the manufacturers technical data sheet. Always be sure to verify the thickness of material your applying and to backroll for better adhesion. Other important steps can include ensuring any rust has been properly addressed and ensuring the roof surface is clean prior to applying the elastomeric coating.