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I've been using a heat gun to speed up filler curing for a decade, but a new guy at our shop in Tampa said it weakens the bond.
He showed me a tech bulletin from 3M that said rapid heat can cause micro-fractures. Now I'm second-guessing my whole process. Do you think a slower cure at room temp is actually stronger, or is this just overthinking it?
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kim.stella3mo ago
That 3M bulletin is pretty specific... micro-fractures sound like a real thing. Have you tried testing it yourself on some scrap material? Like, do a heat gun cure and a room temp cure, then try to pry the parts apart. I'd be curious if the failure point is actually different or if it's just a tiny lab result that doesn't matter in the real world.
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nancy303mo ago
Wait, isn't the bulletin about using a heat gun on the adhesive while it's curing? I thought the whole point was that heating the part itself after it's set can cause those cracks.
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taragrant2mo ago
... but honestly I think people get too caught up in what the bulletin says versus what actually happens in a real shop. I've done it both ways on hundreds of panels and never once saw a crack from hitting it with a heat gun after it cured. The whole micro-fracture thing sounds like something they came up with in a lab under perfect conditions that never play out when you're working with dirty metal and old paint. If you're careful and don't blast it with enough heat to melt the panel itself, I really don't see how it causes any more problems than letting it cure cold and slow.
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