Analysis of IOTA High-Temperature Silicone Mold Release Technology: Causes of Smoke and Buildup, and Selection Guide for Methyl Phenyl Silicone Oil
Why do molds smoke and accumulate buildup during continuous high-temperature molding?
The appearance of smoke and yellowish-brown buildup on mold surfaces is a common issue during continuous high-temperature molding operations. However, this phenomenon cannot be simply attributed to insufficient silicone oil viscosity; a systematic investigation of multiple factors is required: Is the actual mold surface temperature higher than the nominal temperature rating of the selected material? Are low-molecular-weight components, diluent carriers, or atomizing agents volatilizing at high temperatures? Is the silicone oil undergoing thermal oxidation due to prolonged exposure to heat in the air? Is excessive application causing material not involved in the release process to accumulate on the mold surface? Are plasticizers, oligomers, or filler treatment agents from the molding material migrating to the mold surface?


Different phenomena point to different sources of failure. White mist appearing immediately after spraying is usually associated with low-boiling-point carriers or overspraying; yellowish-brown residue appearing after continuous operation often indicates prolonged thermal oxidation or exudation from the molding material; localized black charring requires investigating temperature differentials across the mold and the repeated heating of old residue. Residue color alone cannot determine chemical composition; when necessary, fresh oil, mold residue, and molding material exudates should be collected separately for comparative analysis.


Increase viscosity or switch base oils? IOTA’s differentiated solutions
Regarding the issues mentioned above, simply increasing the silicone oil viscosity is not a universal solution. Higher viscosity does not equate to greater stability under all high-temperature conditions; high-viscosity silicone oils may be more difficult to apply in a uniform, thin layer, potentially increasing the risk of buildup due to localized overspray.


Anhui IOTA Silicone Oil Co., Ltd. (IOTA) offers a multi-grade product portfolio tailored for high-temperature mold release applications:


IOTA-257 High-Temperature Mold Release Agent—Features a polysiloxane structure co-modified with long-chain alkyl and aralkyl groups. It withstands temperatures exceeding 300°C; the oil phase endures mold temperatures without smoking, carbonizing, or leaving residue on the mold. It boasts an active ingredient content of over 99% and a viscosity of 1000–1500 cSt. Suitable for mold release applications involving aluminum alloy die-casting and products made of polyurethane, epoxy resin, or PVC, as well as high-temperature lubrication scenarios such as tire molding and engineering plastic molding.


IOTA 256 High-Temperature Resistant Silicone Oil—An aralkyl-modified polysiloxane capable of withstanding temperatures up to 360°C. In applications involving mold release agents for synthetic fiber spinnerets in chemical fiber plants—which require continuous operation at a constant 300°C for 24 hours—standard silicone oils and conventional phenyl silicone oils fail to meet the requirements, whereas IOTA 256 performs reliably.


IOTA-28027 Long-Chain Alkyl Modified Silicone Oil—Features a dual-modified structure (long-chain alkyl and phenyl groups) and is available in various viscosity grades (600–4500 cSt). Compared to standard alkyl silicone oils, the phenyl structure significantly enhances high-temperature resistance, wear resistance, and lubricity. It produces minimal carbon deposits or residue during high-temperature processing, making it a specialized low-residue mold release silicone oil for die-casting.


IOTA-2437 Methyl Phenyl Silicone Oil—A low-viscosity methyl phenyl silicone oil primarily used as an internal mold release agent for thermoplastic and thermosetting resin systems. It offers excellent high-temperature stability and release performance; adding just 0.01% to 0.5% to the resin pellets facilitates easy mold release.


IOTA 250-30 Methyl Phenyl Silicone Oil—A polymethylphenylsiloxane characterized by low viscosity, a low freezing point (-45°C), good heat resistance, a flash point ≥240°C, and a low expansion coefficient. It combines excellent electrical properties with high-temperature stability, making it suitable for diverse applications such as mold release, anti-stick additives, and insulating impregnation.


What needs to be confirmed before selecting a product? Before specifying a silicone oil grade or viscosity, we recommend verifying the following operating conditions: actual mold surface temperature and peak local temperature; production mode (intermittent vs. continuous), duration of heat exposure per cycle, and cumulative run time; open heating vs. relatively enclosed environment; molding material system and characteristics of any outgassing/deposits; release agent type (neat silicone oil, emulsion, solvent-based, or spray); application quantity, dilution ratio, and re-application frequency; and whether downstream processes involve painting, printing, or bonding.


IOTA recommends validation through comparative testing: keeping the mold, molding material batch, and production conditions constant, compare the current material against IOTA candidate solutions regarding smoke generation cycles, oil film formation time, mold cleaning intervals during continuous production, and product surface contamination to determine the optimal solution based on actual data.


We invite you to visit us at CHINACOAT 2026 to discuss high-temperature mold release solutions in person.
CHINACOAT 2026 will be held from November 11 to 13, 2026, at Area A of the China Import and Export Fair Complex in Guangzhou. Marking the event's 30th anniversary, the exhibition will span 9.5 halls with a total exhibition area exceeding 99,000 square meters.


We welcome you to visit our booth: Hall 6.1


Anhui IOTA Silicone Oil Co., Ltd. will showcase its full range of products, including high-temperature release silicone oils, methyl-phenyl silicone oils, and long-chain alkyl-modified silicone oils. We will provide on-site consultation for product selection and sample testing services for high-temperature molding release applications. Our technical team will analyze your specific operating conditions—such as mold temperature, production cycle time, and molding material system—to help determine the most suitable silicone oil grade and application method.


Booth Information


Exhibition Name: CHINACOAT 2026


Dates: November 11–13, 2026


Venue: Area A, China Import and Export Fair Complex, Guangzhou (No. 380 Yuejiang Middle Road, Haizhu District, Guangzhou)


Our Booth: Hall 6.1


We look forward to meeting you and working together to solve challenges related to smoke and residue buildup in high-temperature mold release processes.