{"id":10912,"date":"2026-07-28T00:00:51","date_gmt":"2026-07-28T00:00:51","guid":{"rendered":"https:\/\/longchangchemical.com\/?p=10912"},"modified":"2026-08-09T12:30:14","modified_gmt":"2026-08-09T12:30:14","slug":"waterborne-direct-to-metal-topcoat-additives","status":"publish","type":"post","link":"https:\/\/longchangchemical.com\/it\/waterborne-direct-to-metal-topcoat-additives\/","title":{"rendered":"Additivi per finiture DTM a base acquosa: Level, Air e Rub"},"content":{"rendered":"

Waterborne DTM topcoat additives<\/strong> can improve wetting, flow or air release, but they cannot create corrosion protection that is missing from the binder, pigment package, metal preparation or dry-film build. Start with the exposed-film defect, then compare one wetting\/leveling route and one foam-control route. Keep handling additives behind a data gate until dosage and metal-topcoat compatibility are documented.<\/p>\n

\n
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Panel architecture<\/strong>
Metal, pretreatment, DTM binder, pigment and film build.<\/div>\n
Visible defect<\/strong>
Wetting\/leveling or entrained-air branch.<\/div>\n
Approval<\/strong>
Adhesion, water, corrosion, rub and recoat.<\/div><\/div>
Original waterborne DTM topcoat map: protect the coating architecture before tuning the exposed surface.<\/figcaption><\/figure>\n

What makes a DTM topcoat decision different<\/h2>\n

A broad waterborne direct-to-metal formulation must balance substrate adhesion, corrosion resistance, pigment wetting, foam, application and cure. A topcoat-focused decision begins later: the DTM architecture is fixed and the exposed film still has a specific appearance or handling defect. This page therefore addresses final laydown and trapped air. The broader waterborne DTM additive guide<\/a> covers system-level diagnosis, while the DTM primer guide<\/a> focuses on the metal interface and corrosion-critical first layer.<\/p>\n

Lock the metal panel and application controls<\/h2>\n

Document alloy, cleaning, pretreatment, blast profile where relevant, time between preparation and coating, wet and dry film thickness, application viscosity, spray pressure, flash, cure and aging. Apply the control and candidates at comparable film build. ASTM D823<\/a> provides practices for producing uniform coating films on test panels. It helps control comparison panels, but a production spray trial is still required before approval.<\/p>\n

Supported and gated product routes<\/h2>\n\n\n\n\n\n\n\n
Itinerario<\/th>\nPublic evidence<\/th>\nUse it to test<\/th>\nDo not infer<\/th>\n<\/tr>\n<\/thead>\n
CHLUMILE\u00ae 3345<\/a><\/td>\n100% active polyether-modified polysiloxane; waterborne\/solvent\/UV; 0.1\u20131.0% of total formulation; wetting and leveling<\/td>\nUneven spread, crater\/pinhole tendency linked to wetting, orange peel and visual flow<\/td>\nCorrosion resistance, universal adhesion or the maximum safe dose<\/td>\n<\/tr>\n
CHLUMICRYL\u00ae DF-D9904BR<\/a><\/td>\n30% active, silica-free polyether-modified polysiloxane compound in DPM; water-based systems; 0.1\u20131.0% total formula<\/td>\nMicrobubbles, foam carry-through and pinholes traced to entrained air<\/td>\nLate-add suitability: the page requires high shear and does not recommend post-addition<\/td>\n<\/tr>\n
CHLUMIAG\u00ae 3501<\/a><\/td>\n100% active acrylic-modified silicone oil; public applications include printing inks, wood coatings, overprint varnish and release coatings<\/td>\nOnly a supplier-supported handling\/release experiment<\/td>\nA public dosage, metal-topcoat use case or quantified anti-block result<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Use 3345 when the visible film will not settle<\/h2>\n

3345 is the stronger first route when the topcoat shows poor spreading, edge pullback, crater-prone wetting or orange peel. Its page supports dynamic\/static surface-tension reduction, substrate wetting, leveling, recoatability and use in waterborne PU. Screen within the published 0.1\u20131.0% total-formulation range, beginning low. Keep viscosity, application settings and film build constant.<\/p>\n

Some defoaming is described, but that qualitative statement should not replace a dedicated air-management screen. At each dose record surface appearance, gloss, foam, pinholes, intercoat behavior and adhesion. A smoother panel is not automatically a more durable or corrosion-resistant panel.<\/p>\n

Use D9904BR when air is the root cause<\/h2>\n

D9904BR addresses a different process. Its page supports prevention of microbubbles and pinholes in water-based coatings and inks. It contains 30% active material in dipropylene glycol methyl ether, so compare both as-supplied dose and active contribution. The recommended 0.1\u20131.0% range is based on total formulation.<\/p>\n

Incorporation is decisive: the page recommends premixing into co-solvent and adding to the grind under high-speed stirring; it specifically says high shear is needed and post-addition is not recommended. Record shear rate, time, temperature and point of addition. If production cannot reproduce the lab incorporation route, the lab result is not transferable.<\/p>\n

Why 3501 is not a first blind screen<\/h2>\n

The 3501 page supports an anti-sticking\/release-oriented application family, but there is no public dosage<\/strong> and no public metal-topcoat dose or application. It also provides no quantified blocking, friction, rub or recoat result. That makes it an evidence-gated route. Request a current TDS, dose, compatibility statement and test method before introducing it.<\/p>\n

If handling or stacking is the true failure, define pressure, temperature, dwell time and contact material. Do not use 3501 to mask incomplete cure, excessive film build or packing a warm coating.<\/p>\n

Run a diagnostic trial rather than an additive cocktail<\/h2>\n\n\n\n\n\n\n\n\n
Panel<\/th>\nChange<\/th>\nPrimary readout<\/th>\nGuardrail<\/th>\n<\/tr>\n<\/thead>\n
A<\/td>\nUnchanged control<\/td>\nDefect count, gloss, adhesion and corrosion baseline<\/td>\nSame batch and film build<\/td>\n<\/tr>\n
B\u2013D<\/td>\n3345 low\/mid\/high<\/td>\nWetting, orange peel, crater and recoat<\/td>\nWatch foam and over-wetting<\/td>\n<\/tr>\n
E\u2013G<\/td>\nD9904BR low\/mid\/high<\/td>\nFoam density, microbubbles and pinholes<\/td>\nUse the required high-shear grind route<\/td>\n<\/tr>\n
H<\/td>\nBest supported candidate<\/td>\nFull cure and durability set<\/td>\nNo combination until single-additive effects are understood<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Measure adhesion with its limitations visible<\/h2>\n

Use ASTM D3359<\/a> as an agreed tape-adhesion reference for coated metal and record the exact failure locus. The method is intended to determine whether a minimum adhesion level is met; it is not sensitive to fine differences at high adhesion. Test both dry panels and panels after the water or corrosion exposure required by the customer specification.<\/p>\n

Keep corrosion testing separate from appearance<\/h2>\n

Surface additives should be approved only if they do not weaken the full DTM system. Use the agreed customer or industry corrosion protocol with fixed scribe geometry, substrate preparation, film thickness, cure and evaluation intervals. Record blistering, rust, undercutting and adhesion after exposure. Do not claim salt-spray hours from a wetting or defoamer product page; these pages provide no such evidence.<\/p>\n

Check handling and abrasion after full cure<\/h2>\n

For an exposed industrial topcoat, compare abrasion only after the specified cure. ASTM D4060<\/a> provides a Taber Abraser method for organic coatings on rigid surfaces. Fix the wheel, load, cycles, resurfacing and film thickness. Also run the actual packing, stacking or assembly simulation, because laboratory abrasion does not reproduce every handling contact.<\/p>\n

Selection rules<\/h2>\n