Temperature

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When dispensing polyurethane foam, two temperatures must be considered.

First and most important is the chemical temperature. If the chemical temperature is not right, you will not dispense good quality foam.

Ideal chemical temperature is between 60° F and 80° F. VERSI-FOAM is equipped with a temperature sensing strip that helps you determine that the chemical temperature is within the ideal range.

The temperature sensing strip shows three colors - blue indicating that the chemicals are too cold, red indicating that the chemicals are too warm and green indicating that the chemicals are within the ideal temperature range. Perfect temperature will indicate in the center of the green indicator.

Good quality foam is light beige in color. It will set up to be tack free in 30 to 45 seconds. After approximately 20 minutes, it will be firm to the touch with a consistent skin.

If the chemicals are too cold, you are probably dispensing foam that is "A" component rich. It will be darker in color and may have a crunchy, glassy surface texture. Warm them up, shake the tanks vigorously and check the chemical flow from the face of the gun. (Click on Checking the Gun for Proper Function for the procedure).

If the chemicals are too warm, you are probably dispensing foam that is "B" component rich. It will be whiter in color and have a spongy surface texture. Cool them down, shake the tanks vigorously and check the chemical flow from the face of the gun (Click on Checking the Gun for Proper Function for the procedure).

The second temperature consideration is that of the surface temperature. This is important to ensure the optimum yield and in some cases, good adhesion.

Ideal surface temperature is between 60° F and 80° F.

Surfaces that are colder will result in reduced yield. This is caused by the cold surface extracting the heat from the exothermic reaction resulting in a reduced rise, thus a reduced yield. If the surface is 40° or colder, the exotherm may also cause condensation, which would be like spraying foam onto a wet surface, therefore, the foam may not adhere to the surface. The only way to determine if this will happen is to do a test patch. If the foam sticks to the cold surface, spray the least thickness possible to simply raise the surface temperature to a level that would be closer to ideal temperatures. Allow that layer to cure. Then add the desired thickness to achieve your R-factor.

Surfaces that are too warm may result in the foam curing too fast. This would also result in a reduced yield because the foam would not have enough time to reach the full rise before a tack free state. In addition, extreme cases may result in loss of adhesion because the foam would cure so fast it could not develop a bond to the surface before it hardened.