Can coating additives must be selected by resin system, cure, fabrication and contact requirements—not by a generic can-coating label. CHLUMIAG® 3467 is a reactive polyurethane route with three different dosage bases. CHLUMIFE® 3307X is a solvent/UV scratch-and-recoat route that requires predilution. CHLUMIFE® 3166 is removed from the first shortlist because it can cause pinholes, whitening and foam stabilization.
None of these public pages establishes food-contact, migration, retort or flavor/odor compliance. Obtain declarations for the exact product, dose, layer, can type and market.
Can coating decision map
| Coating evidence | Conditional route | Approval gate |
|---|---|---|
| Confirmed PU system needs reactive surface modification | 3467 after reaction review | Exact dose basis, batch OH, cure and compliance |
| Solvent or UV exterior film needs scratch balance and recoat | 3307X | Predilution basis, adhesion, forming and package contact |
| Waterborne film already has pinhole/whitening/foam pressure | Correct baseline process | Do not start with 3166 |
| Resin/cure or regulatory route is undefined | No surface-additive selection | Define construction first |
| Product | Published data | Possible role | Critical boundary |
|---|---|---|---|
| 3467 | 100% active; OH ≤85 mg KOH/g; water/UV/solvent | Reactive PU leveling, wetting, scratch/abrasion and anti-sticking study | Three dosage bases; page emphasizes PU coatings/foam/leather, not can qualification |
| 3307X | 100% active; 0.1–1%; UV/solvent, not water | Scratch/abrasion, leveling, smoothness and recoat study | Must first be diluted to 12.5%; dose basis after dilution is unclear |
| 3166 | 100% active; 0.05–1%; water/UV/solvent | Dry-feel study only after a stable non-contact baseline | Explicit pinhole, whitening and foam-stabilization risks |
Define the can construction
Record internal or external layer, steel/aluminum grade, pretreatment, primer/base/topcoat stack, resin/crosslinker, pigments, application, dry film and cure. Add forming sequence, seam/contact zones, fill product, pasteurization or retort and storage conditions.
Internal coatings and closure compounds have different exposure and compliance requirements from decorative exteriors. A surface effect approved on an external panel cannot be transferred to product-contact service.
Keep 3467 reaction-aware
3467 is published as 100% active with an OH value only specified as ≤85 mg KOH/g. Its routes are 0.05–1% of total formulation for solvent systems, 0.5–5% of resin for resin modification and 0.5–5% of total formulation for water systems. These values are not interchangeable.
Request the actual use route and batch OH/equivalent before changing NCO/OH balance. Check pot life, cure, extractables-relevant documentation, adhesion, hardness, chemical resistance and recoat.
Use 3307X only inside its system boundary
3307X is a 100%-active solvent/UV product; waterborne use is explicitly unavailable. Its page instructs dilution to 12.5% with a named solvent blend before use, then states 0.1–1% of total formulation without clarifying whether that range refers to neat product or working dilution.
Resolve the dose calculation before trial. Equalize the dilution solvents in the blank and confirm their regulatory, bake and odor acceptability. Measure scratch, abrasion, gloss, recoat, adhesion and forming—not feel alone.
Why 3166 is not a first screen
3166 may improve dry feel and surface smoothness, but pinholes, whitening and foam stabilization are explicit supplier warnings. Those risks conflict with high-speed application, visual appearance and barrier continuity.
If a non-contact external project later requires dry feel, test it separately after cure and foam are stable. Do not infer can or food-contact suitability from a broad industrial application table.
Reproduce fabrication and thermal exposure
- Apply the complete coating stack at production film weights.
- Match flash, oven profile and peak-metal temperature.
- Form, draw, bend or seam in the actual direction.
- Expose to the required fill simulant, pasteurization or retort cycle.
- Repeat adhesion, cracking, corrosion/barrier and appearance checks.
Measure metal adhesion and flexibility
ASTM D3359 rates tape adhesion of relatively ductile coatings on metal and is insensitive to small differences at higher adhesion. ASTM D4145 evaluates flexibility and adhesion of prepainted sheet under bending.
Define film thickness, cut spacing, bend direction, temperature and forming severity. Add customer methods for sterilization, enamel rating, seam, flavor/odor, migration and filled-pack storage.
Require document and aging gates
Before a product-contact trial, obtain the current composition/regulatory declaration, migration or extraction support, use restrictions and traceable TDS/CoA for the exact grade. Confirm whether the additive is permitted in the intended coating layer and whether a functional barrier or cure condition is required. A generic non-hazardous shipping statement is not food-contact evidence.
Age coated and formed specimens through the customer’s thermal, humidity and filled-product sequence. Inspect blistering, whitening, staining, corrosion, adhesion, flavor/odor and coating continuity at bends, seams and scored areas. Repeat scratch and recoat only where those operations exist in production.
Common can-coating errors
Ignoring the 3467 denominator
Resin modification and total-formulation percentages cannot be compared directly.
Using 3307X in water
The public page excludes waterborne systems.
Treating application lists as compliance
Require current declarations and package-specific validation.
Request a construction-specific review
Send can type/layer, metal/pretreatment, coating stack, resin/crosslinker, dose basis, cure, forming, fill/contact, thermal cycle, target markets and adhesion, scratch, recoat, barrier and compliance requirements. Ask Longchang Chemical to review 3467 or 3307X only against the complete can-coating construction.