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Variable heat, dual-temp. 1500W gives even shrink without scorching the outer. Avoid open-flame lighters at all costs.
Measure bundle OD. The right tubing is two sizes — one expanded (slides on), one recovered (seals tight).
Razor or sharp shears. Square cut on the end means even recovery. Frayed end means uneven shrink and a weak seal.
Workbench mat or scrap board. Heat gun + plastic countertop = problem. Bench protection saves the install (and the bench).
The rule: tubing's expanded ID must clear your bundle. Its recovered ID must be smaller than the bundle so it grips. Aim for 20–30% shrink for a clean seal — not 100%.
Rule: expanded ID ≥ bundle × 1.1 · recovered ID < bundle OD
Cut tubing 3× the joint length. Slide it well past the splice — onto an insulated section. You'll move it back once the wires are joined.
Make the electrical joint — solder, crimp, twist-cap, whatever the spec calls for. Then slide the tubing back so the joint sits centered. 25% overhang on either side.
1500W heat gun. 6 inches off. Start at the center and sweep outward in both directions. Recovery begins at ~90°C, completes at 120°C — about 8 seconds at full power.
Let the joint cool 30 seconds untouched. With 3:1, you'll see a tiny bead of adhesive at each end — that's the hermetic seal. With 2:1, recovery is smooth, no wrinkles, full grip.
A lighter or torch chars the outer before the inner recovers. Always use a heat gun.
Too-big tubing leaves a gap. Too-small won't slide on. Measure twice, order once.
Single-wall is water-resistant, not waterproof. Use 3:1 adhesive for any wet joint.
Burns the outer, leaves the inner cold. Sweep — don't dwell.
Let the solder joint cool first. Adhesive seal degrades if the joint is > 150°C.
Shape sets as it cools. Bend during cooldown and the seal cracks. 30 seconds, untouched.