RLD-10B Anti-rust Oil is a thin-film, solvent-borne temporary corrosion preventive intended for medium-term preservation of ferrous machined surfaces, stampings, and assembled components during interprocess storage and domestic transit. At 25 °C, kinematic viscosity is specified as 4.8–8.2 mm²/s by ASTM D7042-21a, flash point is 61 °C minimum by closed-cup ASTM D93-20, and dry film thickness after a 60 s ambient dip is typically 4–10 µm depending on drainage time and part temperature. The product deposits a non-tacky, amber translucent oil film from a solvent carrier; when applied at 8 µm to degreased SAE 1010 steel, the film withstands 24 h in ASTM D1748-22 humidity cabinet testing at 49 °C and 100% relative humidity without rust, while ASTM B117-19 neutral salt spray resistance is limited to 8–16 h at the same film thickness. The anti-rust mechanism combines polar sulfonate adsorption at the metal interface with a hydrophobic mineral oil barrier. RLD-10B is not formulated with nitrite or amine carboxylate vapor-phase inhibitors.

What Differentiates RLD-10B from Heavy-Duty Solvent-Free and Water-Based Protectives?

Relative to solvent-free heavy hydrocarbon preventives, RLD-10B has lower initial viscosity, faster solvent flash-off, and a thinner final film. At 25 °C, solvent-free grades used for long-term outdoor protection typically deposit films above 50 µm and remain tacky; RLD-10B produces a 4–10 µm film that is dry to touch within 15–30 min at 25 °C and 50% relative humidity. That thin film reduces rework during final assembly. In production-scale bearing interprocess storage, removal may be omitted where residual oil is compatible with bearing grease, whereas heavy wax films require hot alkaline wash or vapor degreasing before torque wrenching. Compared with water-based flash-rust preventives, RLD-10B does not introduce free water into blind holes or crevices and does not accelerate rusting on cast iron when parts are stacked before dry-off. Its solvent carrier is flammable, however; spray application requires ventilation and electrical grounding according to IEC 60079-10-1:2020 zoning and local fire code, whereas water-based products carry no flash point.

Solvent Evaporation and Film Formation on Cold-Rolled Steel Are Controlled by Ambient Humidity and Part Temperature.

Film thickness from dip application is influenced by drainage viscosity, part temperature, and solvent evaporation rate. At 20 °C and 40% RH, a 60 s immersion of a 50 mm × 100 mm degreased steel coupon followed by 30 min vertical drainage deposits 6–8 µm; raising part temperature to 35 °C lowers wet-film viscosity and may reduce dry film thickness to 3–5 µm. Below 10 °C, the product can thicken and drain unevenly; application below 5 °C is not recommended because solvent evaporation becomes too slow and condensation can be trapped under the film. At relative humidity above 80%, evaporative cooling can reduce part surface temperature below dew point, producing visible hazy film and decreasing salt spray resistance by approximately 30–50% when compared with laboratory-controlled 50% RH application. For spray application, air-assisted airless equipment with nozzle orifice 0.23–0.33 mm and fluid pressure 0.7–1.4 MPa yields wet coverage of 18–26 m²/L; conventional siphon spray guns with 1.0–1.4 mm orifice may produce higher overspray and lower transfer efficiency.

In a production-scale machining transfer line, RLD-10B was applied by overhead reciprocating spray nozzles to dry cast iron bearing housings after aqueous cleaning and hot-air drying at 60–70 °C. Residual part temperature at application was 28–38 °C; film thickness measured by eddy current using ASTM B499-09(2021) ranged from 4.2 µm to 7.8 µm across 140 parts. No visible flash rust appeared during 10-day indoor storage at 55–65% RH, while unprotected control housings showed 4–6% surface rust under ASTM D610-08 by day 3. However, in parts with blind M8 tapped holes, solvent retained in the threads required 20 min additional air blow-off to prevent local film wash-out and rust at thread roots; this is a processing bottleneck not observed with solvent-free wax but acceptable for short-cycle interprocess storage.

When RLD-10B Replaces a Heavier Wax Preservative in Export Packaging

Substitution of RLD-10B for high-viscosity wax-oil preservatives reduces cleaning burden and film residue but narrows the protection envelope. Heavy waxes frequently provide 12–24 months of sheltered outdoor storage and 100–200 h salt spray at 50–100 µm; RLD-10B at 8–12 µm is intended for 6–12 months indoor storage in sealed or poly-lined packaging. In export packaging of machined cast iron flanges, field records from a South Korean chassis component line indicate that crates sealed with 0.15 mm VCI polyethylene and coated with RLD-10B exhibited no corrosion on exposed machined faces after 90-day sea transit, while unpackaged control flanges showed edge rust within 18 days. The product must be applied after alkaline cleaning and drying to moisture-free surfaces; residual ionic contamination above 5 µg/cm² sodium equivalent by ISO 8502-6:2020 reduces salt spray performance and may induce under-film corrosion before the listed 6-month limit. Within the RLD series, RLD-10B is the low-viscosity intermediate grade. RLD-10A is a solvent-wipe liquid with lower non-volatile content and is used for short indoor hold periods; RLD-20B is a higher non-volatile oil for export preservation requiring 15–20 µm films. RLD-10B is selected when the application line cannot tolerate heavy residues but corrosion conditions are more aggressive than those suitable for RLD-10A.

Compatibility Boundaries and Surface Preparation Requirements

Because the solvent carrier remains flammable even after film drying, spray application requires mechanical ventilation and elimination of ignition sources in accordance with local fire codes. RLD-10B is designed for ferrous substrates and zinc-phosphated steel. It is generally compatible with nitrile, fluorocarbon, and polytetrafluoroethylene seals after carrier evaporation, but prolonged contact with natural rubber or butyl rubber may cause swelling because the mineral oil fraction remains liquid. The product is not recommended for copper, brass, or magnesium alloys without validation: sulfonate components can stain copper-based alloys under high humidity, and magnesium surfaces may form surface salts if retained moisture is present. Published data for RLD-10B on magnesium alloys is limited. Before application, surfaces must be cleaned to dust and chloride standards under ISO 8502-3:2017; a chloride limit of 5 µg/cm² is typical for 12-month indoor storage. The film should be removed prior to painting, powder coating, welding, or adhesive bonding. Removal is achieved by alkaline immersion wash at 60–80 °C with pH 9.5–10.5, or hydrocarbon solvent wipe for small areas. The product is not a dielectric; it should not be applied to electrical contacts, commutators, or brake friction surfaces. It should not be exposed to open flame, hot surfaces above 120 °C, or used in confined spaces without ventilation. Liquid storage in sealed drums at 5–35 °C is recommended; shelf life is 24 months from date of manufacture when unopened. Under regulatory screening, the product is classified as flammable liquid category 3 according to CLP Regulation (EC) No 1272/2008; its solvent fraction is subject to hazardous air pollutant reporting under 40 CFR Part 63 for U.S. emission sources. It does not contain prohibited substances under EU RoHS Directive 2011/65/EU Annex II as routinely applied to metal preservatives, but local disposal requirements under EU Waste Framework Directive 2008/98/EC require segregation from watercourses.