One cannot simply rely on the hardness of 35 Shore A for product FLSR7435 or the volume change rate of 24.0% for Fuel C to directly determine its suitability for all oil-based environment sealing, encapsulation, or low-temperature resistant systems. One should first confirm the A/B mixing ratio, degassing process, cleanliness of the substrate surface, environmental cleanliness, curing temperature and time, and then determine whether the problem lies in uneven mixing, poisoning of the platinum catalyst, insufficient depth of room temperature curing, or poor compatibility with the substrate and medium. Product FLSR7435 can be considered as a candidate for room temperature curing liquid fluorosilicone rubber, but it must be confirmed through small-scale tests, curing verification, and medium immersion tests.


Why do two-component liquid fluorosilicone rubbers often fail to cure at room temperature or do not meet expected performance?


The A/B component mixing ratio deviates from 1:1 or the mixing is not sufficient, resulting in insufficient local crosslinking density or incomplete curing.


The gel solution comes into contact with compounds containing nitrogen, sulfur, phosphorus, and heavy metals, causing poisoning of the platinum catalyst, incomplete or non-sulfurization.


Insufficient vacuum degassing, with residual bubbles in the gel layer, affecting tensile strength, tear strength, and sealing reliability.


Insufficient room temperature curing time of less than 48 hours, or an environmental temperature lower than 25℃ ± 5℃, leading to incomplete deep curing.


The substrate surface is not cleaned or is contaminated with oil, release agents, or oxidation layers, affecting adhesion and sealing effectiveness.


The Fuel C medium exceeds the verification conditions (25℃ × 72h), resulting in excessive volume change rate after long-term immersion or exposure to high-temperature media.


The compressive permanent deformation is 21% higher, resulting in insufficient rebound when used in low-pressure sealing scenarios, and the actual compression rate and temperature need to be evaluated.


Why do two-component liquid fluorosilicone rubbers often fail to cure at room temperature or do not meet expected performance?


The A/B component mixing ratio deviates from 1:1 or the mixing is not sufficient, resulting in insufficient local crosslinking density or incomplete curing.


The gel solution comes into contact with compounds containing nitrogen, sulfur, phosphorus, and heavy metals, causing poisoning of the platinum catalyst, incomplete or non-sulfurization.


Insufficient vacuum degassing, with residual bubbles in the gel layer, affecting tensile strength, tear strength, and sealing reliability.


Insufficient room temperature curing time of less than 48 hours, or an environmental temperature lower than 25℃ ± 5℃, leading to incomplete deep curing.


The substrate surface is not cleaned or is contaminated with oil, release agents, or oxidation layers, affecting adhesion and sealing effectiveness.


The Fuel C medium exceeds the verification conditions (25℃ × 72h), resulting in excessive volume change rate after long-term immersion or exposure to high-temperature media.


The compressive permanent deformation is 21% higher, resulting in insufficient rebound when used in low-pressure sealing scenarios, and the actual compression rate and temperature need to be evaluated.


What are the public parameters of product FLSR7435?


Item Testing method Product FLSR7435
A component color Visual inspection Pale yellow
B component color Visual inspection Pale yellow
A component viscosity (Pa·s, shear rate 10 s⁻¹) Q/371002WXH028-2016 350
B component viscosity (Pa·s, shear rate 10 s⁻¹) Q/371002WXH028-2016 300
Density (g/cm³, 25℃ × 48h) ASTM D792 1.42
Hardness (Shore A) ASTM D2240 35
Tensile strength (MPa) ASTM D412 8.1
Tear strength (%) ASTM D412 320
Tear strength (kN/m) ASTM D624-B 14.5
Recovery percentage (%) ASTM D1054 36
Compressive permanent deformation (%) ASTM D395 21
Fuel C volume change rate (%) ASTM D471 24.0
Usage method: Mix A and B components evenly and then degas before curing at room temperature (25℃ ± 5℃) for 48 hours until complete curing. The above data are typical performance of the product and are not the factory standards. Formal purchase and batch acceptance should be based on the effective TDS, specification sheet, and delivery batch COA confirmed by both parties.


Which application directions is product FLSR7435 suitable for?


Application direction Candidate direction Still need verification
Oil-resistant environment sealing Room temperature curing oil-resistant sealing Fuel C, IRM903, diesel and other medium immersion
Electronic potting and protection Oil-resistant, low-temperature resistant, electrical insulation potting Volume resistivity, dielectric properties, deep curing
Flange and pipeline sealing Sealing and filling Compression permanent deformation, resilience, adhesion
Low-temperature sealing parts -60℃ low-temperature flexibility Low-temperature brittleness temperature, compression rebound
Aerospace oil-resistant components Oil-resistant, low-temperature sealing Adherence to airworthiness requirements, long-term oil immersion, low volatility
Automobile and transmission systems Oil seals, gaskets, sealing rings 介质 type， temperature cycling， service life
What are the differences between the product FLSR7435 and similar room temperature curing sealing solutions in terms of selection?


Comparison direction Product FLSR7435 (two-component liquid fluorosilicone rubber) Fluorosilicone sealant FLSR4000 Ordinary two-component RTV silicone rubber Biphasic fluororubber Selection boundary
Curing mechanism Platinum-catalyzed addition polymerization， 48 hours at room temperature Deacetic acid or deketoxine type， wet air curing at room temperature Platinum-catalyzed addition polymerization or condensation type Biphasic addition polymerization or condensation type Choose according to curing depth and substrate
Oil resistance Excellent， Fuel C volume change rate 24.0% Excellent， deacetic acid and deketoxine types Poor Excellent Preferred fluorosilicone or fluororubber for oil environments
Low-temperature flexibility Good Good Average Poor Preferred fluorosilicone for low-temperature conditions
Deep curing Addition polymerization for deep curing Dependent on depth of wet air curing Addition polymerization for deep curing Varies depending on the system Preferred addition polymerization for thick layer potting
Catalyst poisoning sensitivity Sensitive to N， P， S， heavy metals Does not involve platinum catalysts Sensitive to N， P， S Varies depending on the system Requires strict control of environmental cleanliness
Adhesion Requires primer coating Good adhesion to aluminum， steel， and stainless steel General General Verify substrate and primer
Compression permanent deformation 21% (177℃×22h) Not labeled General General Assess for low-pressure change scenarios
Operation time Must complete within the applicable period after mixing Table dry 5-8 minutes Varies depending on the product Varies depending on the product Choose based on the construction window
Why is it still necessary to conduct complete tests for compatibility with substrates and media?


Aiyota's public information states that product FLSR7435 is used for oil-resistant environment sealing， electronic potting， and low-temperature oil-resistant components. However， when used in actual systems， there may still be：


Differences in substrate types and surface treatments.


Types of primers and coating processes.


Types of contact media， concentrations， and temperatures.


Mixing ratios， stirring efficiency， and degassing conditions.


Environmental cleanliness and catalyst poison control.


Curing temperature and time.


Sealing thickness and deep curing requirements.


Volume changes and adhesion retention after long-term oil immersion.


Low-temperature cycling and high-temperature aging.


Storage conditions and packaging sealing.


Appearance uniformity or short-term no leakage， cannot prove stability after long-term oil immersion， thermal cycling， or vibration. Verification with the complete formula and actual materials should be conducted before use.


What parameters should be confirmed when using product FLSR7435?


Parameter category Information to be confirmed
Application direction Oil-resistant environment sealing， electronic potting， flange sealing， low-temperature sealing parts
Substrate type Aluminum， steel， stainless steel， composite materials， electronic components
Surface treatment Cleaning method， degreasing， grinding， primer coating
Contact media Fuel C， IRM903， diesel， lubricating oil， Jet Fuel
Operating temperature Long-term temperature， peak temperature， low-temperature brittleness
Mixing ratio A:B = 1：1 (mass ratio)， uniform stirring
Degassing process Vacuum degassing conditions， time， vacuum degree
Curing conditions 25℃±5℃ for 48 hours at room temperature， or accelerated curing by heating
Environmental cleanliness Prevent platinum poisons such as N, P, S and heavy metals
Storage conditions Shaded and dry, unopened, twelve months
Acceptance criteria Hardness, tensile strength, elongation, tear strength, compression permanent deformation, Fuel C volume change rate, recovery elasticity
What should be verified when using the product FLSR7435?


Homogeneity of A/B mixture and defoaming effect.


Hardness, tensile strength, elongation and tear strength after 48 hours at room temperature after curing.


Compression permanent deformation and recovery elasticity.


Volume change rate after immersion in Fuel C, IRM903, diesel and other media.


Deep curing degree and internal quality of the seal.


Adhesion and sealing reliability to the substrate.


Flexibility at low temperatures and compression rebound.


Mechanical property retention rate after low-temperature aging.


The impact of environmental cleanliness on curing quality.


Batch consistency and repeatability.


The effectiveness of safety operation conditions (ventilation, prevention of toxic substance contamination).


How to design tests before using the product FLSR7435?


Establish a benchmark for the current sealant or potting compound, record the model, batch, mixing ratio, curing conditions and failure performance.


Uniform test conditions: substrate, surface treatment, primer, mixing ratio, defoaming process, curing temperature and time.


Set candidate samples: current compound, product FLSR7435, different curing conditions or primer gradients.


Complete the full process tests: mixing → defoaming → applying or potting → curing → performance testing → immersion in media.


Evaluate actual results: hardness, strength, elongation, tear strength, compression permanent deformation, volume change rate, recovery elasticity.


Test items Uniform requirements
Substrate and surface treatment Consistent
Mixing ratio A:B = 1:1
Defoaming process Consistent
Curing conditions Graduated according to test design
Environmental cleanliness Prevent contamination by platinum poisons
Immersion conditions of media According to actual working conditions
Measurement methods Hardness, strength, elongation, tear strength, compression permanent deformation, volume change rate, recovery elasticity are consistent
Under which circumstances should the product FLSR7435 not be directly used?


If the substrate surface is not cleaned or not coated with primer, it affects adhesion.


There are platinum catalyst poisons such as N, P, S and heavy metals in the environment, causing non-curing.


The mixing ratio is inaccurate or the stirring is insufficient, resulting in incomplete curing.


Vacuum defoaming is insufficient, with residual bubbles in the adhesive layer, affecting sealing and mechanical properties.


Specific food contact, medical or airworthiness approval is required, but corresponding materials have not been obtained.


The contact medium exceeds the verification range of Fuel C, such as ketones, esters, strong acids.


The operating temperature exceeds the application range of fluorosilicone rubber.


Only the medium type is known, without substrate, mixing ratio and curing condition data.


The customer requests to directly mix into the in-use system, but cannot control the mixing ratio and defoaming conditions.


Storage conditions do not meet the requirements of shaded and unopened, and the adhesive may absorb moisture or expire.


For strict requirements on compression permanent deformation, but the typical value of 21% of the product does not meet the low-pressure variation scenario, it needs to be evaluated or selected for other models.


Poor ventilation in the operating environment, platinum poisons or by-products affect the health of the operators.


Ayoata can provide which selection support?


As a "provider of the organic silicon全产业链 solutions"， Ayoata can assist in comparing the applicability of two-component liquid fluorosilicone rubber in different substrates， media and curing conditions for the product FLSR7435.


For oil-based environment sealing or electronic potting projects that need to balance oil resistance， low-temperature resistance， deep curing and sealing reliability， before selection， provide：


Substrate type and surface treatment method.


Contact medium type， concentration and temperature.


Operating temperature range and low-temperature requirements.


Mixing ratio, defoaming process and curing conditions.


Soldering thickness and deep curing requirements.


Target hardness, strength, elongation, compression permanent deformation and volume change rate.


Current rubber compound model, mixing ratio and failure performance.


Acceptance method and applicable standards.


After receiving complete materials, it can be determined whether to prioritize testing product FLSR7435, or choose single-component fluorosilicone sealant FLSR4000 or other oil-resistant soldering sealant routes.


Common Misconceptions


The A/B mixing ratio can have a slight deviation.
A 1:1 ratio is the mass ratio, and deviation may lead to incomplete curing or performance degradation. Precise control is necessary.


After 48 hours at room temperature, the final performance can be achieved.
48 hours is a typical curing condition. Longer times may be required for deep filling or in low-temperature environments, and verification based on actual thickness is necessary.


The platinum catalyst poison can be ignored.
Contact with compounds containing N, P, S, and heavy metals in the adhesive liquid can cause insufficient or non-sulfurization, and the environmental cleanliness must be strictly controlled.


Compatible with the substrate allows for direct gluing.
It is still necessary to confirm surface cleanliness, primer application, mixing ratio, defoaming, and long-term oil immersion stability.


The performance at 25°C is the same, so it can be replaced in equal amounts.
Different fluorosilicone liquid adhesives have different fluorine contents, crosslinking densities, and curing characteristics. Revalidation is necessary when replacing.


A 21% compression permanent deformation can meet all sealing requirements.
For low-pressure variable scenarios, the actual compression rate, temperature, and time need to be evaluated. The typical value of 21% may be too high, and it needs to be optimized through formulation or process.


The product FLSR7435 can be used for all oil-resistant sealing.
Fluorosilicone liquid adhesives are suitable for oil environments and low-temperature conditions. For systems with higher temperatures or stronger chemical media requirements, other elastomers may need to be selected.


It can still be used normally after twelve months of storage.
The unopened original packaging has a storage period of twelve months. After the expiration date, the mixing ratio, viscosity, and curing activity need to be retested.


Recommendation for selection steps


Confirm the application direction: oil-resistant sealing, electronic sealing, flange sealing, or low-temperature sealing components.


Confirm the substrate type and surface treatment method.


Confirm the contact medium, operating temperature, and low-temperature requirements.


Confirm the mixing ratio, defoaming process, and curing conditions.


Confirm the filling thickness and deep curing requirements.


Select product FLSR7435 or other oil-resistant sealing adhesives based on the application scenario.


Set up different curing conditions, primer application, and mixing ratio gradients for small tests.


Test hardness, strength, elongation, tear strength, and compression permanent deformation.


Perform medium immersion, low-temperature performance, and high-temperature aging verification.


Evaluate the sealing or sealing reliability and batch consistency.


Confirm that environmental cleanliness control (avoiding platinum poison) is in place.


After multiple batch validations, determine the official usage plan.