How to Choose the Right Release Agent for Different Mold Temperatures

In industrial production such as die casting and injection molding, mold temperature plays a crucial role in determining both release performance and mold life.

• High-temperature molding processes—such as aluminum and magnesium die casting, high-temperature plastic compression molding, and carbon fiber/epoxy composite curing—require release agents with superior heat resistance, lubrication, and stability.
• In contrast, low-temperature applications—such as concrete casting and rubber molding—focus on film-forming ability, environmental friendliness, and low residue.

Choosing the right release agent ensures excellent demolding results, environmental safety, and long-term mold protection.

As a professional release agent manufacturer and exporter, we combine global industry experience and customer feedback to share effective strategies for selecting the right release agent under different mold temperature conditions.

# Part 1: Mold Temperature – A Key Variable in Release Agent Selection

A release agent works by forming a thin barrier layer on the mold surface to prevent substrates—such as rubber, plastic, composites, or metal—from sticking or fusing to the mold. This allows for smooth, efficient demolding of parts.

However, achieving this seamless separation depends on properly matching the chemical properties of the release agent with the specific process conditions. Among all process parameters, mold operating temperature is the most critical factor in selecting the right release agent.

Choosing an unsuitable type can directly result in sticking, surface defects, mold fouling, and ultimately, costly production downtime.

# 1.1 How Temperature Affects the Effectiveness of the Release Barrier

The performance of a release agent on the mold surface fundamentally depends on its thermal stability, viscosity, and wettability at a given temperature.

# 1.1.1 Volatility and Degradation

Excessive mold temperature is the primary cause of release agent failure. When the mold temperature exceeds the thermal stability limit of the release agent’s active ingredients or carrier (solvent/water), rapid evaporation, thermal cracking, or chemical decomposition may occur.

Such degradation not only destroys the release film—leading to sticking—but also generates toxic fumes, unpleasant odors, and hard carbon residues or fouling on the mold surface. Over time, this buildup accumulates through multiple production cycles, eventually requiring costly shutdowns and cleaning.

High-performance release agent formulations are designed to resist thermal degradation:

• Standard silicone-based release agents can typically withstand temperatures up to 204°C (400°F).
• High-temperature silicones can tolerate up to 315°C (600°F).
• In extreme environments such as metal die casting, specialized formulations must endure temperatures as high as 982°C (1800°F).
• Water-based release agents generally offer lower heat resistance and should be selected according to the specific mold temperature range.

# 1.1.2 Viscosity and Wetting

The actual operating temperature of the mold has a significant impact on the viscosity of the release agent, which in turn affects its spreading and wetting ability on the mold surface.

• Low-Temperature Environments: When the mold temperature is too low, the release agent may become overly viscous, making it difficult to apply evenly. This is especially critical for molds with complex geometries or fine textures, as uneven coating can result in an incomplete barrier, leading to demolding issues.
• Wetting Optimization: Silicone-based release agents are known for their low surface tension, which allows them to spread easily and wet intricate or irregular mold surfaces effectively. This property is crucial for forming a continuous and uniform film on complex molds.

# 1.2 Performance and Production Efficiency: Thermal Stability Buffer

For manufacturers pursuing high production efficiency, selecting a release agent must go beyond the simple criterion of “non-stick.” Since thermal degradation and fouling are the main causes of unplanned downtime for mold cleaning, choosing a release agent with thermal stability only slightly above the actual mold temperature poses significant production risks.

Based on our experience, it is essential to select a release agent with a sufficient thermal stability buffer within the operating temperature range. This means that even if the mold experiences temperature fluctuations or localized hotspots during normal production, the decomposition point of the release agent should be well above these peak temperatures.

Example: In a thermoplastic injection molding process with a mold temperature of 200°C, manufacturers should consider using a high-performance or semi-permanent silicone release agent that can withstand 300°C or higher. This strategy prevents long-term thermal degradation and fouling, extends the interval between reapplications, reduces unplanned downtime, and ultimately maximizes overall equipment efficiency and mold lifespan.

# 1.3 Core Chemical Types of Release Agents and Their Thermal Performance Overview

Release agents can be categorized based on their base chemistry and carrier type. Understanding the thermal performance of each type is a prerequisite for making the right selection:

Table 1: Thermal Performance of Release Agents

Release Agent Type	Typical Temperature Range	Environmental Profile	Best For
Water-Based	149∘C (300°F)	Low VOCs, Eco-Friendly	Polyurethane, Concrete, Epoxy Resins
Silicone-Based	204∘C(400°F)	Moderate VOCs (Solvent-Based), Wide Temperature Adaptability	General Molding, Rubber, Plastics
Solvent-Based	260∘C (500°F)	High VOCs	Complex Geometries, Fast Cycles
Semi-Permanent	371∘C(700°F)	Moderate VOCs (Typically)	High Volume Production, Complex Parts
Specialty High-Temp	982∘C (1800°F)	Varies	Engineering Resins, Metal Die Casting

# Part 2: Optimal Release Agent Selection for Low/Room-Temperature Molds (0°C–150°C)

Low- and room-temperature applications mainly include thermoplastic injection molding (using cold molds), polyurethane (PU) foam molding, precast concrete, and certain epoxy resin casting processes.

In this temperature range, the selection focus typically shifts from heat resistance to environmental compliance, fast film formation, and cost-effectiveness.

# 2.1 Water-Based Release Agents: The Mainstay for Low-Temperature Molding and Sustainability

Water-based release agents are the preferred choice for low- to medium-temperature applications, typically suitable for mold temperatures not exceeding 150°C (300°F). Their core advantages lie in environmental friendliness and safety.

# 2.1.1 Environmental and Safety Advantages

Water-based formulations use water as the primary component and contain little to no volatile organic compounds (VOCs). Because they do not emit VOCs, water-based agents are safer for workers and have minimal environmental impact, complying with increasingly strict international HSE (Health, Safety, Environment) regulations and the green procurement requirements of OEM customers. In addition, they are generally more cost-effective and easy to apply.

# 2.1.2 Application Challenges and Quality Control

Despite their environmental advantages, water-based release agents face a key challenge in low-temperature molds: drying time. Since water evaporates more slowly than solvents, residual moisture may remain if the mold temperature is low or production cycles are short.

This residual moisture poses an “invisible steam” risk in low-temperature applications, threatening product quality (e.g., bubbles, surface irregularities). In more severe cases, in polyurethane molding, residual water from the water-based agent may even react chemically with the molded material, reducing part performance.

Solution: It is crucial to apply under thoroughly dry conditions. We develop formulations with fast-drying additives and also recommend gently heating the mold to 82°C (180°F) to accelerate water evaporation and film curing.

# 2.2 Special Applications of Wide-Temperature and Low-Temperature Silicone Emulsions

Silicone-based release agents provide stable demolding performance over a very wide temperature range due to their excellent cold resistance. Certain silicone compounds, such as grease-type formulations, maintain usable viscosity and service performance at temperatures as low as -40°C, while still resisting heat up to 204°C.

# Part 3: Ensuring Performance for Medium- and High-Temperature Molds (150°C–370°C)

The medium- to high-temperature range of 150°C–370°C covers most rubber vulcanization, thermosetting plastics (such as phenolic resins and polyesters), and high-performance thermoplastics molding processes.

Within this range, release agents must provide excellent thermal stability and long-lasting performance to support continuous, high-speed production cycles.

# 3.1 Performance Limits of Conventional Solvent-Based and Standard Silicone Release Agents

# 3.1.1 Solvent-Based Release Agents: Fast Film Formation vs. Environmental Trade-Offs

Solvent-based release agents typically withstand temperatures up to 260°C (500°F). Their main advantage lies in rapid film formation: organic solvents evaporate quickly, leaving a thin, smooth, active layer on the mold surface.

However, solvent-based agents usually contain high VOC levels, which pose health and environmental challenges. This has driven the industry to seek alternatives with similar performance but lower VOC content.

# 3.1.2 Applications of Standard Silicone

Standard silicone release agents are widely used in general plastics and rubber molding due to their excellent versatility, low cost, and good heat resistance up to 204°C (400°F). Silicone not only provides efficient demolding but also offers excellent chemical and thermal stability.

# 3.2 Semi-Permanent Release Agents: The Cornerstone of High-Throughput Production

For medium- to high-volume continuous production, semi-permanent release agents are a core technology to ensure efficiency.

# 3.2.1 Performance and Durability

The mechanism of semi-permanent agents involves forming a durable, cross-linked chemical film on the mold surface. This film provides higher thermal stability, typically withstanding temperatures up to 371°C (700°F). By reducing the frequency of reapplication (allowing multi-release), they significantly minimize production downtime, thereby increasing throughput and operational efficiency.

# 3.2.2 Suitable for Thermosetting Molding and EPDM

Semi-permanent agents are especially suitable for high-capacity production, such as rubber vulcanization (e.g., EPDM) and thermosetting material molding, which often involve continuous high-temperature operation (150°C–300°C).

# Part 4: Extreme Conditions and Ultra-High Temperature Solutions (370°C +)

When mold temperatures exceed 370°C, entering the fields of metal casting and special engineering resin molding, the selection of release agents must rely on specialized chemicals with extreme thermal stability.

# 4.1 Chemical Requirements for Ultra-High Temperature Applications

1. Ultra-High Thermal Stability: The agent must withstand temperatures above 370°C without rapid thermal degradation or decomposition.
2. Anti-Soldering Property: In die casting, it must prevent molten metals (such as aluminum) from chemically bonding or “soldering” to the mold surface.
3. Lubricity: Ensure smooth material flow and easy demolding under extreme pressure conditions.

# 4.2 Specialty Dry-Film Lubricants: Graphite and Boron Nitride

Specialty dry-film lubricants are critical solutions for ultra-high temperature molding environments. These formulations are typically based on inorganic solid lubricants, such as boron nitride (BN).

Boron Nitride Release Agents: Certain boron nitride formulations exhibit exceptional thermal stability, maintaining functionality across a wide temperature range—from room temperature up to 850°C (1562°F). The dry-film nature minimizes residue and mold buildup while offering excellent anti-stick and barrier properties.

The modern die-casting release agent market is undergoing a shift toward water-based formulations. Advanced zero-VOC, water-based die-casting agents now deliver a wide operational range of 100°C to 800°C.

Table 2: Die Casting Temperature and Types of Release Agents

Die Temperature Range	Recommended Chemistry
Low Temperature (150°C–250°C)	Standard Water-Based Agents
Medium Temperature (250°C–350°C)	Enhanced Thermal Stability Formulas
High Temperature (350°C+)	Specialty High-Temperature Releases

# Part 5: Common Temperature-Related Troubleshooting

Based on our extensive field experience, we have summarized several temperature-related issues frequently encountered in molding processes, along with their corresponding solutions.

Table 3: Temperature-Related Troubleshooting Methods

Malfunction/Issue	Temperature-Related Causes	Expert Solutions
Part Sticking / Difficult Release	Mold temperature is too high, leading to rapid release agent decomposition/evaporation; Mold temperature is too low, causing poor wetting or incomplete curing.	Confirm mold temperature is within the release agent’s designed range; Use a heating system to assist in drying water-based agents; For high heat issues, switch to higher-grade semi-permanent or specialty high-temperature formulations.
Smoke / Odor / Mold Build-up	Mold temperature far exceeds the thermal decomposition point of the release agent; Release agent applied in excessive amounts.	Reduce the amount of release agent applied; Switch to zero VOC dry film agents or new water-based agents with higher thermal stability; Check the mold cooling system.
Air Bubbles / Spotting on Product Surface	Incomplete drying of water-based agents, causing moisture to vaporize at high temperatures; Release agent reacts with the molded material.	Strictly adhere to drying/curing times; Ensure mold temperature reaches at least 82°C (180°F) to promote film formation for water-based agents; Verify chemical compatibility.

# Conclusion: Choosing the Right Release Agent for Global Manufacturing Efficiency

Selecting the right industrial release agent according to mold temperature is the foundation for ensuring stable demolding performance, mold protection, and production efficiency. From water-based release agents for low-temperature polyurethane or concrete applications to semi-permanent and boron nitride-based formulations for high-temperature die casting and composite molding, every process demands a tailored chemical solution with the right balance of thermal stability, lubricity, and environmental compliance.

As a professional release agent manufacturer and exporter from China, Yunzhu New Materials provides a full range of water-based, solvent-based, silicone, and high-temperature release agents designed for rubber, plastic, concrete, composite, and metal casting industries. Our products have been adopted by major industrial and construction enterprises, helping overseas manufacturers achieve cleaner demolding, higher yield, and safer operations.

With years of R&D expertise and international experience, we continue to support global partners in selecting the most suitable release agent for different mold temperature conditions, ensuring long-term performance, environmental sustainability, and consistent surface quality in every production cycle.

Contact Yunzhu New Materials for technical consultation, customized formulations, or to learn more about our industrial release agent solutions for export markets.