{"id":"mech-007","license":"CC-BY-4.0","data":{"title":"How intumescents swell shut (before/during)","file":"/diagrams/mech-007-intumescents-before-during.svg","caption":"FA Exhibit MECH-007. How intumescents swell shut.","alt":"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.","kind":"diagram","rights":"cc-by-4.0","depicts":"Under fire heating, an intumescent matrix can melt, generate many small gas bubbles, swell, and solidify into a thick multicellular char","identifiableAddress":false,"exifGpsStripped":true,"derivation":"AFTER NIST BUTLER / BAUM / KASHIWAGI + NIST R0200473.","technicalReviewer":"Grayson Graham","lastVerified":"2026-08-25T00:00:00.000Z"}}