# Multi-Pan Eyeshadow Palette Retention: Snap-Fit Undercuts, Hot-Melt Adhesive Creep, and Drop Demolding
TL;DR — A multi-pan eyeshadow palette only holds together if the geometry that captures each pan and the process that bonds it agree: snap-fit undercuts seat the pan, hot-melt is an option for bonding, and the failure that matters is the pan coming loose on impact. No eyeshadow palette model is recorded in the catalog; a palette is a format applied to the compact multi-pan family of 16 catalog models with pan capacities from 1.7 ml to 20 ml, including a multi-pan layout of 0.9 ml × 9. Pan retention is part of the project design, not a recorded catalog detail — the undercut geometry, adhesive recipe, and demolding behavior below are engineering guidance, configured and confirmed per project.
Why: A Palette Is a Compact Multi-Pan Format, Not a Separate Product
An eyeshadow palette is not a distinct product record — it is a format applied to the compact multi-pan family. The retention problem is therefore the same compact problem, repeated across many small cavities at once:
- Every pan must sit still. A multi-pan palette multiplies the geometry task: seat all pans evenly or a single high point can hold the lid off its neighbors;
- Retention is a geometry problem first. Snap-fit undercuts decide how firmly each pan is captured in its seat;
- Bond is a process problem. Where hot-melt is used, adhesive behavior — creep above all — decides how that seat holds over months of closure;
- Drop is the real-world test. The pan that pops out of its socket on impact is the palette that feels broken from the first drop, even if it never opens again;
- The program documents the family, not the format. Catalog models and pan capacities are recorded; the retention design for any palette is a project decision.
How: Retention as Geometry plus Process
3.1 What the compact family actually documents
The compact family records 16 catalog models, with pan capacities measured from 1.7 ml to 20 ml, including a multi-pan layout of nine 0.9 ml pans. One of those layouts is exactly the pattern an eyeshadow palette draws on. The base substrate of each compact is a project-level configuration, with no fixed material sheet claimed. These are the documented anchors of the family.
3.2 The palette: a format, not a recorded model
No eyeshadow palette model is recorded in the catalog. A palette is a format applied to the compact multi-pan family — the same pans, the same family, arranged for eyeshadow. This is a deliberate framing: the retention engineering does not belong to a palette product line, but to the multi-pan compact construction each project specifies. Nothing is recorded for the palette's retaining system itself: no structure, no geometry, no bond method.
3.3 Snap-fit undercuts: the geometry track
The route that needs no adhesive rests on molded undercuts that capture the pan flange or rim. Working knowledge of any press-fitting part governs the essentials:
- An undercut lets the pan click into its seat to a defined depth and holds it there against lateral motion and lift;
- Too little interference and the pan can dislodge under handling; too much, and insertion stresses the thin-wall housing or distorts the pan.
Neither undercut dimensions nor interference values are published — both are set and confirmed against the specific part geometry and material pairing in each project.
3.4 Hot-melt adhesive creep: the process track
Where the project bonds the pan rather than capturing it with snaps, the hot-melt route carries its own time-dependent risk. A molten adhesive that grips on day one can relax over sustained closure as the bond line creeps, especially under heat. The failure is slow and invisible: the pan loosens in its seat long after the first tolerance check passed.
The bond recipe — adhesive type, application, and the surface it bonds to — is made against the formula and its fill temperature, the refill strategy where the palette is refillable, and the drop performance target. No amounts or dwell values are published.
3.5 Drop demolding: the failure mode to verify
For a palette, the consequence that unites both tracks is drop behavior: the shock that can pry a pan out of a snap seat or open a weakened bond line. Drop demolding is what the program's verification actually guards against. Drop testing checks that no pan comes loose when the closed palette takes a shock; torque testing checks the open/close behavior that moves and stresses the pans (and the palette hinge) on every use; leakage and vacuum testing check that pan seating never opened a path in the sealed system. All four are documented capabilities of the program (capability-level, no parameters published).
<pre class="language-mermaid"><code>flowchart LR
A[Compact multi-pan family<br/>16 models, 0.9 × 9 layout] –> B[Eyeshadow palette format<br/>no recorded model – format application]
B –> C[Snap-fit undercuts<br/>geometry, per project]
B –> D[Hot-melt adhesive<br/>creep risk, per project]
C –> E[Drop demolding risk]
D –> E
E –> F{Drop + torque + seal gates}
F –> G[Release per project]
</code></pre>
What: Verified Program Data and the Verification Hooks
- Product family: the compact family records 16 catalog models;
- Pan capacities: measured across the family from 1.7 ml to 20 ml, including a multi-pan layout of nine 0.9 ml pans;
- Format boundary: no eyeshadow palette model is recorded in the catalog; a palette is a format applied to the compact multi-pan family, not its own product line;
- Base substrate: project-level configuration, with no fixed material sheet claimed;
- Component boundary: pan retention is part of the project design, not a recorded catalog detail; the undercuts, adhesive, and demolding behavior have no catalog record;
- Verification hooks (capability-level): drop test, torque test, leakage test, and vacuum test are documented testing capabilities, with no parameters published.
Gotchas
- A palette has no catalog record. No eyeshadow palette model, structure, or retention geometry is recorded; treat any specific palette retention design as a project obligation, not a documented fact.
- No published geometry or bond values. Undercut dimensions, interference, adhesive amounts, and demolding forces are all per-project values — anything quoted from memory is fabrication.
- Snap-fit and hot-melt fail in different ways. Snap retention fails by tolerance stack and stress concentration; hot-melt fails by creep and squeeze-out; they are not interchangeable drop-in routes.
- Drop demolding cuts across both tracks. A pan can pop out of a snap seat exactly where a bond line was already weakened — verify the assembled palette as a whole, not the bond and the snap separately.
- Capacities are recorded; holding is not. The measured pan range (1.7–20 ml) is real; the holding behavior of a pan in a specific palette remains per-project configuration and test.
Related Resources
- Category: Compacts
- Related insight: Compact Godet Pan Retention · Airtight Cushion Compacts: Gasket Creep & Pan Sealing · Cushion Sponge Cell Architecture · Magnetic Closure Luxury Compacts · The 12-Test Lab Matrix
- Quality & Testing Capabilities — drop, torque, leakage, and vacuum testing