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scott moss Posted: Jul 30, 2009 09:51 PM	curing time I've been reading and realize that alot of sprayers have trouble with spraying too much foam at one time and not allowing the foam to cure or what ever it does, causing strong chemical smell aong with other issues. I guess my question is how long do you have to let oc foam sit before reapplying another coat of foam to reach desired depth.
mason Posted: Jul 31, 2009 07:27 AM	Different formulas have different curing times particularly when it comes to odors. The type of catalyst used determines how much odor comes from the foam. Some catalyst (like Polycat 8) give off strong odors that can take days to dissipate. Other catalysts may only give off noticeable odors for a few hours. But open cell sprayfoams should give off less odor than closed cell foam and the odors should dissipate sooner (due to the total amount of material per thickness compared to air in the cells and the ability of the foam to release any fumes quicker because of the open cell content of the foam. Open cell sprayfoam is typically installed in one lift thickness and should not have significant odors emitted from it within a few hours after application. Closed cell sprayfoam is typically installed in more than one lift thickness (industry guidelines recommend up to 1.5 inches per lift) and then allow 10 -15 minutes for the exothermic heat to dissipate. When installed under these application conditions, odors should be gone within a few hours to a few days. (It could take longer depending on how much ventilation is in the space.) If the foam is installed is lift thickness greater than 1.5 inches or if multiple lifts are applied before the exothermic heat can dissipate, the odors can linger much longer in the foam. For example, I have cut into foam that is over one year old and detected a strong odor of catalyst. There are other factors that can affect the strength of the odor. Slightly off ratio foam (particularly b rich) foam not mixed well moisture contamination on the substrate (causes a B rich mixture at the substrate/foam interface) Also, note that strong odors can come from pesticide treatments, treated wood, adhesives, and drywall made in China. Be sure the house is already well ventilated of these odors before installing the foam. Once you have sealed the home tight, these odors can linger much longer and your foam will be blamed.

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Comments

scott moss

Posted: Jul 30, 2009 09:51 PM

curing time

I've been reading and realize that alot of sprayers have trouble with spraying too much foam at one time and not allowing the foam to cure or what ever it does, causing strong chemical smell aong with other issues. I guess my question is how long do you have to let oc foam sit before reapplying another coat of foam to reach desired depth.

mason

Posted: Jul 31, 2009 07:27 AM

Different formulas have different curing times particularly when it comes to odors. The type of catalyst used determines how much odor comes from the foam. Some catalyst (like Polycat 8) give off strong odors that can take days to dissipate. Other catalysts may only give off noticeable odors for a few hours.

But open cell sprayfoams should give off less odor than closed cell foam and the odors should dissipate sooner (due to the total amount of material per thickness compared to air in the cells and the ability of the foam to release any fumes quicker because of the open cell content of the foam.

Open cell sprayfoam is typically installed in one
lift thickness and should not have significant odors emitted from it within a few hours after application.

Closed cell sprayfoam is typically installed in more than one lift thickness (industry guidelines recommend up to 1.5 inches per lift) and then allow 10 -15 minutes for the exothermic heat to dissipate. When installed under these application conditions, odors should be gone within a few hours to a few days. (It could take longer depending on how much ventilation is in the space.)

If the foam is installed is lift thickness greater than 1.5 inches or if multiple lifts are applied before the exothermic heat can dissipate, the odors can linger much longer in the foam.

For example, I have cut into foam that is over one year old and detected a strong odor of catalyst.

There are other factors that can affect the strength of the odor.

Slightly off ratio foam (particularly b rich)
foam not mixed well
moisture contamination on the substrate (causes a B rich mixture at the substrate/foam interface)

Also, note that strong odors can come from pesticide treatments, treated wood, adhesives, and drywall made in China. Be sure the house is already well ventilated of these odors before installing the foam. Once you have sealed the home tight, these odors can linger much longer and your foam will be blamed.

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