Waterborne DTM additives should be selected after the coating architecture is defined, not from a generic list of surface claims. Direct-to-metal performance begins with metal preparation, binder adhesion, anticorrosive pigment, water resistance, cure and dry-film build. Wetting agents and defoamers can help the formulated coating reach that potential; they do not replace it.
Alloy, cleaning, profile
Binder, pigment, DFT
Wetting, air, application
Adhesion and corrosion
Use this guide as the system-level decision page
This is the system-level guide for waterborne direct-to-metal coatings. It helps a formulator decide whether the first additive experiment should address metal wetting, process foam or a later surface property. For layer-specific work, use the waterborne DTM primer guide when the first coat controls the metal interface, or the waterborne DTM topcoat guide when the exposed film already has a defined appearance or handling defect.
Establish the non-additive controls first
Record the metal grade, mill scale or oxide condition, cleaning method, surface profile, pretreatment, binder chemistry, PVC, anticorrosive pigment, pH, co-solvent, neutralizer, flash, cure and target dry-film thickness. Prepare panels from the same metal lot and coat them at controlled thickness. ASTM D823 describes uniform-film practices useful for comparative coating panels.
If an unchanged control varies widely, do not rank additives. Resolve bath contamination, panel preparation, foam history, viscosity drift and film-build variation first.
Three product routes with different evidence
| Route | Published facts | Legitimate first question | Boundary |
|---|---|---|---|
| CHLUMICRYL® WD-D547 | 100% active polyether-modified polydimethylsiloxane; water/solvent/solvent-free/UV; 0.1–0.5% | Can metal wetting, anti-cratering or leveling improve at controlled dose? | Broad surface claims do not prove corrosion resistance or adhesion on every metal |
| CHLUMIAF® 094 | 100% active silicone/polyether paste; waterborne only; 50–500 ppm; dilution procedure required | Is persistent process foam obscuring panel quality? | The page’s main applications include harsh process systems; a coating trial must prove film compatibility |
| CHLUMIFE® 3166 | 0.05–1% total formula; water/solvent/UV; feel and abrasion route | Only after the DTM film already passes protection tests: can handling feel or abrasion improve? | Public warnings include pinholes, whitening and foam stabilization |
Start WD-D547 only for a measured surface-entry problem
WD-D547 is supported for wetting, spreading, anti-cratering, recoating, defoaming and leveling. That breadth makes it a useful diagnostic route, but it is not permission to expect every property simultaneously. Run a ladder inside 0.1–0.5% of total formulation and use the lowest dose that produces a reproducible benefit.
Measure initial spread, edge pullback, crater count, gloss, foam, recoat and adhesion. Hold pH, viscosity and film thickness constant. If wetting improves while wet adhesion or corrosion performance declines, the route fails the DTM requirement.
Treat 094 as a controlled foam experiment
094 is 100% active and its published dose is only 50–500 ppm based on total formulation. The page instructs users to dilute for defoaming applications and states that the working solution should be prepared and used immediately. Direct addition is discouraged because dispersion is difficult. Obtain the current TDS procedure before a plant trial and document the true dose of as-supplied product and working solution.
The page identifies waterborne coatings as an application, but it also emphasizes extraction, metalworking, fermentation, papermaking and wastewater. Therefore, verify crater formation, gloss, film clarity, adhesion and storage stability in the exact DTM resin. Do not assume resistance to harsh process pH proves compatibility in a coating film.
Remove 3166 from the first DTM shortlist
3166 is a later-property candidate, not a core DTM wetting or corrosion route. The public page supports feel and abrasion-related use, yet also warns that it may cause pinholes or whitening and may stabilize foam. Those risks directly conflict with early DTM troubleshooting.
Only test it after the control formula already passes metal adhesion, water resistance and corrosion requirements. Use a separate low-dose ladder, inspect foam and pinholes, and repeat the full durability set. Do not combine it with a new wetting agent or defoamer in the first round.
Use a staged matrix
| Stage | Question | Experiment | Pass evidence |
|---|---|---|---|
| 0 | Is the base architecture repeatable? | Three unchanged control panels | Consistent DFT, cure, appearance and adhesion |
| 1 | Is wetting the bottleneck? | WD-D547 low/mid/high | Lower defect count without foam, recoat or adhesion loss |
| 2 | Is entrained air the bottleneck? | 094 controlled dilution ladder | Less foam/pinhole with stable film and storage |
| 3 | Does the candidate preserve protection? | Best single-additive panels | Dry/wet adhesion and agreed corrosion result |
| 4 | Is a later handling property needed? | Separate 3166 trial | Abrasion/feel benefit with no pinhole, whitening or foam penalty |
Measure adhesion before and after exposure
ASTM D3359 is a practical tape-adhesion reference for coated metal. Fix film thickness, cure age, cutting method, tape, removal angle and operator. Record where failure occurs. Because the method does not finely distinguish high adhesion levels, supplement it with the customer’s required wet-adhesion or pull-off method where necessary.
Use corrosion exposure as comparative evidence
ASTM B117 defines operation of salt-spray apparatus, not a universal pass duration or field-life prediction. Agree the specimen, scribe, exposure time and rating criteria before starting. Include replicates and compare the unchanged control with the candidate at equal DFT and cure. Report blistering, rust, scribe creep and adhesion after exposure; do not convert chamber hours directly into years of service.
Review storage and application robustness
A promising day-one panel is not enough. Age the formulated paint at agreed temperature, then recheck viscosity, pH, separation, foam and application. Simulate pump or recirculation shear if the plant uses it. Apply at the low and high ends of the production viscosity and film-build window. An additive that works only on one careful drawdown is not yet a production solution.
Selection rules
- Use WD-D547 for a demonstrated surface-entry or crater problem, then verify adhesion and corrosion.
- Use 094 only as a carefully diluted waterborne foam route with current supplier instructions.
- Do not place 3166 in the first shortlist; test it only after the protective coating already passes.
- Never use a surface additive to compensate for inadequate metal cleaning, wrong anticorrosive PVC, insufficient DFT or incomplete cure.
What to include in an inquiry
Send metal grade and preparation, binder, pigment/PVC, pH, solids, co-solvents, current additive package, process shear, application method, film thickness, cure, defect photographs and required dry/wet adhesion and corrosion specification. Identify whether the immediate failure is wetting, foam, crater, pinhole, corrosion or handling.
Ask Longchang for a waterborne DTM diagnostic ladder based on your actual formula and panel test.