Amid tightening environmental inspections, numerous foundries have phased out conventional oil-based release agents in favor of water-based alternatives to eliminate workshop fumes, reduce VOC emissions and improve working conditions. Nevertheless, frequent operational issues including sticking and tearing, casting porosity, spray gun clogging and emulsion delamination at low temperatures have hampered the transition for many manufacturers. 

The water-based release agents themselves are not inherently defective. Most on-site failures arise because processes and operating practices have not been adapted to the water-based system. Three prevalent on-site problems are outlined below:

Ⅰ. Misoperations in Mixing, a Major Source of Hidden Risks

• Dilution directly with tap water from the plant. Calcium and magnesium ions present in groundwater and hard water destabilize the emulsion, triggering precipitation and agglomeration. This leads to nozzle clogging and mottling or stains on casting surfaces. For castings with high surface finish requirements, soft water or purified water is preferred for dilution. Foundries in hard-water regions must conduct pre-production compatibility tests on small samples.

• Arbitrary concentration adjustment based on experience. Higher concentration does not equate to better release performance. Excessive concentration leaves heavy residues and severe mold fouling. Insufficient concentration results in an ultra-thin coating prone to localized sticking. The dilution ratio shall be determined according to casting structure and mold temperature, rather than copying the formula for oil-based release agents.

Ⅱ. Misoperations in Spraying Process: Defects Occur if Oil-Based Operating Routines Are Adopted Blindly

• Excessive coating build-up. Water-based release agents function through a uniform, thin dry film. Over-spraying leaves residual moisture inside the mold cavity, which fails to evaporate fully before mold closing. Upon molten metal pouring, vaporization generates pinholes and porosity on castings, aggravates mold carbon deposition and extends mold cleaning time.

• Negligence of mold temperature matching. Excessively high mold temperature induces the Leidenfrost effect, where the release agent is repelled by steam upon contact and cannot form an adherent film, resulting in sticking and tearing. Too low mold temperature slows moisture evaporation and also causes porosity. Mold temperature parameters for oil-based release agents cannot be directly applied.

Ⅲ. Misoperations in Storage and Equipment Maintenance: Oversights Lead to Material Failure and Production Shutdowns

• Lack of low-temperature storage protection. Water-based release agents are emulsion systems susceptible to freezing and demulsification at low temperatures. Once frozen, the original emulsion structure is irreversibly damaged even after thawing and stirring, with a sharp drop in performance. Such material should not be used for production. Storage tanks shall be insulated in winter.

• Inadequate cleaning of pipelines and spray guns. Emulsion settles naturally during static storage, so storage tanks require periodic low-speed agitation. Pipelines and nozzles must be thoroughly cleaned before prolonged production shutdowns to prevent agglomeration and clogging, and avoid unplanned line stoppages.

Water-based release agents deliver clear advantages: low smoke and low VOC levels, improved workshop environment and reduced environmental compliance risks. Once the process is stabilized, castings feature clean surfaces that facilitate subsequent grinding and coating operations. These products are not universal; separate grades are required for different processes such as gravity casting and die casting, and cross-process usage is not permitted.

Full-line one-off replacement is not recommended. Small-batch trial production should be conducted first, with gradual optimization of dilution ratio, spraying pressure, drying time and mold temperature. Scale-up can proceed only after defect rates remain stable.

For technical issues such as casting porosity, sticking and spray gun clogging, please contact: xinda01@lnxdzzkj.com. Xinda supplies water-based release agents tailored to specific working conditions together with supporting process guidance to help foundries cut trial-and-error costs.