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FA Exhibit MECH-007

How intumescents swell shut (before/during)

Equal before and during sections show a thin intumescent liner melting, bubbling, swelling, and solidifying into porous multicellular char that occupies a generic gap. No product or rating claim is made.
FA Exhibit MECH-007. How intumescents swell shut. AFTER NIST BUTLER / BAUM / KASHIWAGI + NIST R0200473. Illustrative — not a construction document. Verify with your building official. CC BY 4.0.

Technical review: Grayson Graham. Last verified 2026-08-25. JSON

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