1/2 pound vs 2 pound iso | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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Daniel Arnold Posted: Aug 18, 2008 09:15 AM	1/2 pound vs 2 pound iso most foam suppliers that i deal with say that there are only a few different iso's. Is there a difference between 1/2 pound and 2 pound iso? I use seperate transfer pumps for open and closed cell on "B" side. I use only one "A" transfer pump. I have always purged "A" material when switching between materials. Is this really necessary?
mason Posted: Aug 18, 2008 11:33 AM	While there are only 4 main producers of mdi that is used in sprayfoam (open and closed cell foam) there are some differences in the products that can affect the formula (not just open vs closed cell but among the varieties of open cell and of closed cell as well. ) Your supplier has matched the A side to the B component for optimum results in a specific sprayfoam system. Mixing and matching may bring subtle and not so subtle differences in reactivity, physical properties, etc. Also, the performance testing of the product may also be based on the specific A and B component. If something weird happens to the foam in the field and you have not used the supplier's A and B system, it could void any manufacturer's implied warranty on the system. So before using combinations of different supplier's A and B components, obtain approvals from your supplier in writing.

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Comments

Daniel Arnold

Posted: Aug 18, 2008 09:15 AM

1/2 pound vs 2 pound iso

most foam suppliers that i deal with say that there are only a few different iso's. Is there a difference between 1/2 pound and 2 pound iso? I use seperate transfer pumps for open and closed cell on "B" side. I use only one "A" transfer pump. I have always purged "A" material when switching between materials. Is this really necessary?

mason

Posted: Aug 18, 2008 11:33 AM

While there are only 4 main producers of mdi that is used in sprayfoam (open and closed cell foam) there are some differences in the products that can affect the formula (not just open vs closed cell but among the varieties of open cell and of closed cell as well. )

Your supplier has matched the A side to the B component for optimum results in a specific sprayfoam system. Mixing and matching may bring subtle and not so subtle differences in reactivity, physical properties, etc. Also, the performance testing of the product may also be based on the specific A and B component.

If something weird happens to the foam in the field and you have not used the supplier's A and B system, it could void any manufacturer's implied warranty on the system.

So before using combinations of different supplier's A and B components, obtain approvals from your supplier in writing.

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