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travis fails Posted: Sep 11, 2008 11:37 PM	Humidity Mason I was trying to spray a home in northeast Texas today and was having a shrinkage problem. I tried turning up the heat but still had a problem. The temp was 81 but the humidity was 82. Is there a certain % point of humidity that you need to stop spraying .5 lb. foam? Any info will be helpful.
mason Posted: Sep 12, 2008 08:11 AM	The general rule of the sprayfoam industry is to not spray when the temperature is within 5 degrees of the dewpoint. This may change during the day. Also, check out the substrate moisture content before spraying. Wood should be less than 19% moisture content (as measured with a Delmhorst Moisture Probe) There are very nice portable humidity and temperature gauges available that can provide the relative humidity, temperature, dewpoint and even wind speed. The one I use is a Kestrel 3000. Sure wish I had one when I was contracting. I strongly recommend that all sprayfoam contractors record the temperature, humidity, dewpoint and substrate moisture content everytime they begin spraying foam and take measurements throughout the day. This helps the supplier to know the conditions and assist in troubleshooting when the foam is not acting right. Other things you should record. Lot numbers or the foam, heat and pressure settings, type of gun and proportioner, spray pattern, rise and set times, foam yield, lbs sprayed and any other information about the job that may come in handy later on. It sounds like a lot of info, but actually only takes a few minutes a day. The information can be recorded on a computer file with the job for later reference.

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travis fails

Posted: Sep 11, 2008 11:37 PM

Humidity

Mason I was trying to spray a home in northeast Texas today and was having a shrinkage problem. I tried turning up the heat but still had a problem. The temp was 81 but the humidity was 82. Is there a certain % point of humidity that you need to stop spraying .5 lb. foam? Any info will be helpful.

mason

Posted: Sep 12, 2008 08:11 AM

The general rule of the sprayfoam industry is to not spray when the temperature is within 5 degrees of the dewpoint. This may change during the day. Also, check out the substrate moisture content before spraying. Wood should be less than 19% moisture content (as measured with a Delmhorst Moisture Probe)

There are very nice portable humidity and temperature gauges available that can provide the relative humidity, temperature, dewpoint and even wind speed. The one I use is a Kestrel 3000. Sure wish I had one when I was contracting. I strongly recommend that all sprayfoam contractors record the temperature, humidity, dewpoint and substrate moisture content everytime they begin spraying foam and take measurements throughout the day.

This helps the supplier to know the conditions and assist in troubleshooting when the foam is not acting right. Other things you should record.
Lot numbers or the foam, heat and pressure settings, type of gun and proportioner, spray pattern, rise and set times, foam yield, lbs sprayed and any other information about the job that may come in handy later on.

It sounds like a lot of info, but actually only takes a few minutes a day. The information can be recorded on a computer file with the job for later reference.

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