Spray Foam Supplies In-depth

Spray foam, otherwise known as polyurethane foam, is created by the chemical reaction when mixing two components in their liquid form in the right proportion. The two components are isocyanates (ISO) and polyol resin (RES). When combined, the chemical reaction causes them to expand up to 60 times their liquid volume and generate a virtually air-tight foam used for insulation.


Chemicals Used

As we mentioned before, the two chemicals mixed to create the polyurethane foam are Isocyanates and Polyol resin. The ISO is labeled as A within a proportioner system and the RES is marked as B. It is important not to confuse those labels since residue in the hoses might mix with the opposite chemical and produce foam that could clog the entire system.

Isocyanates (ISO – Side A)

Isocyanates are low molecular weight chemicals that, besides insulation, are widely used in the manufacturing process of flexible and rigid foams, fibers, and coatings such as paints and varnishes. It is critical to wear protective equipment when handling Isocyanates as they are potent irritants of the eyes, stomach, and lungs. Direct skin contact also causes inflammation in the section that made contact.

Polyol Resin (RES – Side B)

Polyols are very large alcohol-type molecules. A blend of different polyols is used as the ingredient for spray foam, so you may hear references to a Polyol Blend when talking about insulation. However, in addition to the polyol, the blend can also contain different additives like catalysts, surfactants, colorants, and blowing agents, which may be hazardous if not handled correctly.


When handling both chemicals, we always recommend using protective gear. At a minimum, we recommend using:

• Safety glasses

• Chemical resistant gloves

• Respirators with proven efficiency against these chemicals

• Protective clothes to prevent skin contact

• Industrial shoes with steel cages for handling the drums and heavy equipment

Besides protective gear, we recommend handling in a very well-ventilated area and that you guarantee a complete cleanse of equipment and clothes before leaving the job zone.

How They Interact

When mixing both substances, a chemical reaction takes place. The liquid substances mixed start to blow up into a solid foam and multiply its volume between 30 to 60 times the original value (depending on closed or open-cell). Once sprayed, depending on the brand of chemicals used, the foam will cure (or harden) in 5 to 60 minutes to reach a tack-free state. The surface will set first, and slowly, the insides will follow. The thicker the foam, the longer it takes to cure. For fully cured foam, the time ranges from 10 to 24 hours, depending on the humidity and temperature of the surrounding areas. An additional factor to consider is that the ratio of one chemical to the other must be 1:1 for the best performance and insulation.

Ratio Requirements

When mixing the two materials in the gun just before spraying, the volume ratio between both chemicals must be the same to guarantee a consistent and robust foam. If the mix is skewed to one side or the other, the hardened foam will not perform correctly. Its consistency will wallow, and the desired R-Value will not be achieved.

Contact Us For More Information

Whether you are a sole operator, have a small crew, or multiple rigs running daily, our spray foam insulation system maximizes your most important asset: your reputation. The Carlisle Fluid Technologies IntelliSpray IS40 reduces the risk of off-ratio jobs, is easy to operate, is built for durability, helps you get jobs done faster, and increases your profitability.

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