Happy National Day & Silicone: Addressing High-Temperature Mold Smoke and Buildup, IOTA Grade Selection, and CHINACOAT Guangzhou News | IOTA


Happy National Day. For industries such as high-temperature molding, rubber, composites, coatings, and adhesives, the periods of continuous production around the National Day holiday and the resumption of work afterward are often times when issues like mold smoke, buildup, and poor mold release become particularly apparent. When smoke and buildup occur on high-temperature molds, one cannot simply conclude that the "silicone oil viscosity is too low" or assume that "switching to methyl-phenyl silicone oil will definitely solve the problem." Instead, one must first determine whether the smoke and residue originate from silicone oil volatilization, thermal oxidation, the spray carrier, excessive application, or exudation from the molding material itself. Within the IOTA series, grades such as IOTA 2056, IOTA 255, IOTA 280, and IOTA 300 can be evaluated as potential solutions; however, the final choice requires verification based on factors such as temperature, air exposure, the molding cycle, and subsequent processing requirements.


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China International Coatings Show
November 11–13, 2026 | Guangzhou
Visit our booth: Hall 6.1, Booth 6.1D59


I. Why do high-temperature molds generate smoke and buildup during continuous production?


1. The actual mold surface temperature exceeds the nominal temperature used during material selection.


2. Low-molecular-weight components, diluent carriers, or atomizing agents volatilize at high temperatures.


3. Silicone oil undergoes gradual performance changes due to continuous exposure to heat in the presence of air.


4. Excessive application leads to the accumulation of material on the mold surface that does not contribute to the release process.


5. Plasticizers, oligomers, filler treatment agents, or other components within the molding material migrate to the mold surface.


6. Incompatibility exists between the new material and residual cleaning agents, oil stains, or old mold release layers. 7. Instability in the nozzle, spraying distance, or atomization pressure leads to excessive local application.


Silicone oils possess low surface tension and good spreading properties, making them suitable for mold release; however, their actual performance depends on factors such as molecular structure, viscosity, formulation type, and application conditions. IOTA 2056 represents the dimethyl silicone oil type; IOTA 255 represents the methyl-phenyl silicone oil type; IOTA 280 is suitable for evaluation in high-temperature release applications; and IOTA 300 can serve as a reference for emulsion, solvent-based, or compounded release systems.


II. How can smoke, oily residues, and carbonized deposits be distinguished?


| Phenomenon | Possible Source | Priority Inspection Area | Comparable IOTA Grade |
|---|---|---|---|
| White mist or smoke appears immediately after spraying | Low-boiling-point carriers, low-molecular-weight components, or overspraying | Volatile composition, mold temperature, spray quantity | IOTA 300 |
| Transparent oil film forms on the mold surface | Excessive application, insufficient transfer, or accumulation of high-viscosity material | Dosage per cycle, spray uniformity, release cycle | IOTA 2056, IOTA 280 |
| Yellowish-brown residue appears after continuous operation | Prolonged heat exposure, oxidation, or exudation from the molded material | Air exposure, temperature, residue source | IOTA 255 |
| Localized black carbonized deposits | Hot spots, repeated heating of old residues, or material decomposition | Mold temperature differences, mold cleanliness, molded material | IOTA 280 |
| Oily surface or contamination on the molded part | Transfer of release agent to the part | Dosage, viscosity, requirements for subsequent coating or bonding | IOTA 2056, IOTA 300 |


Chemical composition cannot be determined solely by the color of the residue. When necessary, samples of the fresh oil, mold residue, and exudate from the molded material should be collected separately for comparative analysis. III. Should you increase silicone oil viscosity or switch to methyl-phenyl silicone oil?


Increasing viscosity may reduce the volatilization of certain low-molecular-weight components, but it is not a universal solution.


1. Higher viscosity does not necessarily equate to greater stability under all high-temperature conditions.


2. High-viscosity silicone oils may be more difficult to apply in a uniform, thin layer, increasing the risk of excessive local application.


3. If the material does not transfer easily from the mold surface, it may accumulate over time, forming an oil film or buildup.


4. If smoke generation stems primarily from diluents, spray carriers, or the molding material itself, increasing the base oil viscosity may not be effective.


Public data from IOTA indicates that silicone oils span a wide viscosity range and offer low volatility and thermal-oxidative stability; however, these are general characteristics of the material class and cannot replace verification based on specific product grades and actual operating conditions. IOTA 2056 is suitable for applications requiring viscosity adjustment of dimethyl silicone oil; IOTA 255 offers high-temperature stability characteristic of methyl-phenyl silicone oil; IOTA 280 is designed for continuous high-temperature mold release; and IOTA 300 is suitable for spray applications, emulsions, or compounded systems.


IV. How should IOTA grades of dimethyl silicone oil and methyl-phenyl silicone oil be compared? | Comparison Item | IOTA 2056 (Dimethyl Silicone Oil) | IOTA 255 (Methyl Phenyl Silicone Oil) | IOTA 280 (High-Temperature Mold Release) |
|---|---|---|---|
| Basis for Selection | Wide viscosity range; proven track record in spreading and mold release | Suitable for applications requiring further evaluation of high-temperature stability | Suitable for high-temperature compression molding and continuous mold release scenarios |
| Key Evaluation Criteria | Viscosity, volatility, spray uniformity, residue | Phenyl content, viscosity, volatility, thermal oxidation, and compatibility | Thermal stability, mold cleaning cycle, residue during continuous operation |
| Potential Risks | Volatility and oxidation must be monitored during continuous high-temperature use | Mold release and buildup performance cannot be judged solely by "phenyl content" | Compatibility with existing systems and impact on downstream processing require verification |
| Verification Focus | Mold cleaning cycle, product transfer, continuous operation stability | Comparison with existing systems regarding release, residue, and downstream processing | Number of release cycles, rate of buildup, product appearance |


Public technical data indicates that methyl phenyl silicone oil can offer superior high-temperature stability compared to conventional dimethyl silicone oil; however, the actual usable temperature range depends on the specific material and operating conditions. While IOTA 255 is a viable candidate, it cannot replace on-site small-scale and pilot-scale testing.


V. What operating conditions need to be confirmed before selecting a product? | Operating Condition Category | Information to Confirm |
|---|---|
| Mold Temperature | Actual measured surface temperature, peak local temperature, and temperature fluctuations |
| Production Method | Intermittent vs. continuous production; duration of single-cycle heat exposure and cumulative operating time |
| Air Exposure | Open heating, local exhaust ventilation, or relatively enclosed environment |
| Molding Material | Rubber, plastic, composite, or other systems and their outgassing products |
| Release Agent Type | Pure silicone oil, emulsion, solvent-based, spray, or compounded release agent |
| Application Conditions | Spray quantity, dilution ratio, nozzle type, spray distance, and re-application frequency |
| Failure Symptoms | Smoke, transparent oil film, yellowish-brown residue, charring, or difficult demolding |
| Subsequent Processes | Painting, printing, bonding, electroplating, or direct assembly |
| Evaluation Criteria | Number of release cycles, mold cleaning interval, product appearance, and surface contamination |


If the information is incomplete, it is not advisable to specify a particular grade or viscosity (e.g., IOTA 2056, IOTA 255, IOTA 280, or IOTA 300) directly.


VI. How to Design a Comparative Test for IOTA Grades?


1. Maintain consistency in the mold, molding material batch, production temperature, and molding cycle.


2. Set up test groups for the currently used material, the IOTA 2056 high-viscosity candidate, the IOTA 255 methyl-phenyl silicone oil candidate, and the IOTA 280 high-temperature release candidate.


3. Standardize the application amount per cycle, spray distance, nozzle type, and re-application frequency; if using IOTA 300, also standardize the dilution ratio.


4. Record the cycle number at which smoke, oil film, and significant buildup first appear.


5. Compare demolding force (or ease of release), product appearance, and mold residue.


6. Record the number of continuous production cycles achieved before the mold cleaning threshold is reached. 7. Conduct verification of subsequent processes for products requiring painting, printing, or bonding.


8. Analyze residues when necessary to distinguish between silicone oil, spray carriers, and exudates from the molding material.


VII. Happy National Day & Silicones: Recommendations for Resuming Production


Happy National Day. When resuming production after the holiday, it is recommended to first clean the mold, measure the actual mold surface temperature, and calibrate the spray volume and atomization pressure. Then, conduct small-batch trials using grades such as IOTA 2056, IOTA 255, IOTA 280, and IOTA 300, while recording observations regarding initial smoke, oil film formation, residue buildup, demolding issues, and mold cleaning cycles. Do not rely solely on "increasing viscosity" or "switching to methyl-phenyl silicone oil" as the only decision-making criteria. The selection of high-temperature demolding silicone oil ultimately depends on operating conditions, the formulation, the application method, and verification through continuous production.


CHINACOAT
China International Coatings Show
November 11–13, 2026 | Guangzhou | Visit Our Booth
Hall 6.1
Booth 6.1D59