Are you hesitating between choosing RTV silicone or regular silicone for your project? Deciding between the two is not difficult. Although both are forms of silicone, they differ in many respects. This article will introduce you to the differences between the two silicones from all aspects to help you make the option that best meets your project needs.
What Is RTV Silicone?
RTV silicone usually comes in liquid or paste form and is applied much like liquid glue—either to fill gaps or to bond objects. It is worth noting that RTV silicone requires neither molds nor ovens; it can cure naturally at room temperature to form a rubber-like material.
What Is Regular Silicone?
Regular silicone refers to finished silicone components that are manufactured at a factory. They are pre-molded silicone gaskets, strips, or rolls. Produced through a high-temperature curing process at the manufacturing facility, this material features a stable structure and is ready for immediate use upon receipt.
Key Differences Between RTV Silicone and Regular Silicone
Surface Properties
Regular silicone is a finished product that has undergone high-temperature vulcanization, resulting in a dry-to-the-touch surface. Consequently, it does not attract or adsorb dust and impurities. Since regular silicone is processed using standardized industrial equipment, it exhibits an exceptionally high degree of surface flatness.
If your product involves strict aesthetic requirements—or if you are designing precision instrumentation—standard silicone is the only viable choice, as it offers precise control over both surface flatness and cleanliness.
During the curing process, RTV silicone remains wet and fluid, so dust and impurities are easily adsorbed onto its surface and are difficult to remove. Furthermore, since RTV requires manual extrusion, its surface flatness is difficult to control, often resulting in irregular contours.
If your product does not impose strict requirements regarding the flatness or cleanliness of the silicone material, opting for RTV may help you realize some cost savings.
Mechanical Properties
After undergoing a mature silicone manufacturing process, regular silicone possesses a highly stable structure, which features an extremely low compression set. Even when subjected to prolonged pressure, it retains the rebound ability.
Therefore, if your project requires maintaining a seal over an extended period, you must choose regular silicone.
Conversely, when subjected to prolonged compression, RTV silicone tends to undergo permanent deformation and will not rebound. Then, the sealing performance of products utilizing RTV may fail after a certain period.
However, upon curing, the silicone forms an integral whole with the substrate. So it is the ideal choice for equipment that is not intended to be disassembled; in such cases, selecting RTV silicone helps prevent displacement at connection points that might occur under severe vibration.
Stretch
Regular silicone possesses outstanding tear resistance, which ensures that it can be stretched significantly without snapping and enables it to withstand repeated pulling and extensive elongation.
If your product incorporates silicone components subject to frequent movement, or if they remain in a stretched state for prolonged periods, the regular silicone is the safest choice.
While RTV silicone can also be stretched, its texture is brittle. So its tear strength is far inferior to that of regular silicone. If subjected to excessive stretching during use, it is prone to tearing.
However, if your project does not involve high-intensity stretching, selecting RTV silicone may help you save on mold manufacturing costs.
Hardness
Regular silicone allows for precise customization of hardness and ensures consistency in hardness across large-volume orders. Manufacturers can produce silicone that is tailored to your exact shore hardness specifications.
If the silicone is intended for use in conjunction with fragile components, regular silicone ensures hardness stability, thereby preventing potential damage to delicate parts caused by inaccurate silicone hardness.
RTV silicone, however, is susceptible to variations in hardness during the curing process—influenced by factors such as temperature and humidity, or inconsistencies in manual application—which can compromise sealing performance.
Nevertheless, RTV silicone offers significant operational flexibility, allowing R&D personnel to adjust formulation ratios on-site to fine-tune the hardness.
If your equipment does not require high precision and requires a silicone material that offers flexibility for adjustment, RTV silicone would be a suitable choice.
Dimensional Tolerance
Regular silicone is manufactured using molds or precision industrial equipment. Since the dimensions of the material after curing are typically established with high precision, tolerance control can generally be maintained within a tight range of 0.1 mm to 0.2 mm.
The dimensions and hole positioning of the finished products are strictly aligned with pre-determined templates, thereby ensuring that every single silicone component produced is consistent.
If you are sourcing our silicone for use in automated manufacturing processes, regular silicone—with its capacity for precise tolerance control—represents the optimal choice.
RTV silicone is in a liquid state during extrusion and remains susceptible to the influence of temperature and impurities until fully cured.
Furthermore, the RTV dispensing process is manually operated, making it impossible to guarantee dimensional consistency across every finished silicone product. The typical tolerance for RTV silicone is over 0.5 mm.
If your product does not impose strict requirements regarding minute variations in sealing thickness, you may opt for RTV silicone as a cost-saving measure.
Safety & Purity
Outgassing
Certain types of RTV silicones generate volatile substances during their curing process. When RTV is used in optical instruments, these VOCs can cause lens fogging; furthermore, upon contact with metal, they can lead to discoloration and corrode copper wiring within the equipment.
If your project involves sealing materials such as plastics or wood, excluding expensive precision instruments or optical devices, or if the product does not require long-term stability, RTV silicone can serve as a cost-effective solution.
Regular silicone often utilizes a platinum-cure process, a method that generates no byproducts during curing. To ensure absolute reliability, manufacturers generally perform a post-cure treatment to eliminate any residual volatile substances. Consequently, the platinum-cured silicone you receive is highly stable.
For applications involving sensitive items, such as precision electronics, precious metals, or equipment containing optical lenses, it is highly advisable to select a regular silicone formulation that does not release volatile substances.
Contamination
When RTV is exposed to the workshop environment during the operation process, impurities present in the surroundings can easily become entrained within the liquid silicone.
However, during the production of regular silicone, manufacturers ensure that the entire process is conducted exclusively within dust-free cleanrooms or enclosed equipment. Thus, the resulting silicone exhibits a very high degree of purity.
If your custom silicone application involves medical devices or requires compliance with food-grade standards, opting for regular silicone will facilitate the successful completion of various regulatory compliance tests.
Compliance
The mixing ratio for RTV is entirely dependent on manual operation. If the ratio is not precise, it can result in incomplete chemical reactions, which may result in the product failing to pass REACH or RoHS testing, and in severe cases, even trigger allergic skin reactions upon contact.
In situations where the use of RTV silicone is necessary, we strongly recommend selecting specific grades that have undergone a comprehensive suite of UL, FDA, or MIL-SPEC certifications to ensure product safety.
Every batch of regular silicone undergoes rigorous laboratory testing. The manufacturing facility is capable of issuing official test reports—such as those for FDA, LFGB, or UL compliance—thereby providing a tested and substantiated guarantee of the material’s safety.
If your project is subject to strict testing protocols or regulatory audits, opting for regular silicone can save you a great deal of trouble.
Cost & ROI
Cost
RTV requires only a caulking gun or an automated dispensing machine, resulting in low initial investment costs. This silicone material is priced per kilogram or per cartridge, and its unit price remains stable.
However, it is important to note that the labor costs of RTV silicone in its manufacturing are extremely high. Furthermore, the curing process for RTV requires an amount of workshop floor space, which may entail substantial facility costs.
Regular silicone requires an initial investment in production molds. The unit price of the silicone fluctuates based on order volume: it is lower for large orders and higher for small ones.
If your custom silicone product features an adhesive backing, the peel-and-stick application takes mere seconds to complete, so the associated labor costs are virtually negligible. Furthermore, the regular silicone products are ready for immediate loading for transport and do not occupy significant storage space.
ROI
For small-batch orders, opting for RTV silicone eliminates the expense of creating molds. This avoids the increase in per-unit product costs of mold fabrication, which yields an extremely low ROI.
Furthermore, the ROI can be further eroded by scrap costs due to issues such as material breakage during use due to uneven thickness, or by post-sales maintenance costs resulting from inadequate sealing performance.
For projects involving medium-to-large-scale production, we recommend opting for regular silicone. This is because the cost of mold fabrication effectively substitutes for manual assembly costs, thereby yielding an exceptionally high ROI.
What’s more, regular silicone offers stable sealing performance, which helps avoid extra after-sales expenses, thereby ensuring that your ROI remains at a high level.
Customization Versatility
RTV silicone offers exceptional flexibility during customization; it requires no pre-fabricated molds and can directly fill irregular gaps. However, once cured, RTV silicone transforms completely into a solid elastomer. If your product calls for a foamed structure, such as silicone sponge or foam material, RTV silicone cannot provide this.
Regular silicone offers more flexibility in form customization; it can be manufactured according to your specific requirements as ultra-thin sheets, custom-shaped strips, or various types of silicone foam. Furthermore, you can tailor the hardness and resilience of the material by giving the shore hardness that you need or controlling the density. In addition, regular silicone also supports coloring based on Pantone color codes.
If your project requires highly diversified custom products, regular silicone will be a better choice.
How to Choose for Industrial Applications
Choose RTV Silicone
Prototyping
During the product design process, the sealing design may require multiple adjustments. In such cases, opting for RTV silicone helps eliminate the high costs associated with custom molds.
Seam Sealing for Large Structural Components
For instance, the seams on shipping containers and large-scale outdoor equipment require filling with silicone. Given that the gaps in such equipment often exhibit different tolerances, RTV silicone enables immediate adjustment to accommodate these specific seam tolerance requirements.
Emergency Repairs
When aging production equipment develops oil or water leaks that cannot be immediately dismantled and replaced, RTV silicone can be applied directly to the damaged area, making it an ideal material for on-site emergency repairs.
Choose Regular Silicone
Electronic and Optical Equipment
For electronic devices with limited internal space—such as mobile phones and tablet computers—internal silicone components must adhere to strictly controlled tolerances and must not emit volatile substances that could corrode the device’s mainboard.
When installed on devices equipped with a lens, the silicone component must remain absolutely clean; any hazing or impurities will compromise lens performance.
Only regular silicone can achieve the above-mentioned results.
EVs
When utilizing silicone for the sealing of new energy vehicle battery packs, an exceptionally high flame-retardant rating (UL 94-V0) serves as a safeguard for product safety. Only regular silicone offers clearly defined flame retardancy standards and provides extrusion resistance performance lasting for 5 to 10 years.
Medical Devices and Food-Grade Products
Only regular silicone strictly complies with FDA or medical-grade certifications; furthermore, the surface of the silicone components does not adsorb impurities, thereby effectively preventing bacterial growth and withstanding frequent high-temperature sterilization and cleaning.
FAQ
RTV Claims to Waive Tooling Fees—Does This Truly Result in Long-Term Cost Savings?
This depends on your order volume. For small-batch orders—or if you are concerned about the potential trial-and-error costs inherent in the customization process—RTV indeed offers a highly cost-effective solution. However, once production volume exceeds 500 to 1,000 units, the accumulated labor costs associated with continuing to use RTV will outweigh the cost of manufacturing multiple sets of standard molds; at this stage, opting for the regular silicone is highly recommended. For procurement professionals who prioritize Return on Investment (ROI), we advise giving precedence to the comprehensive unit cost rather than focusing solely on the unit price of raw materials.
My Gap Tolerances Are Quite Wide—prefabricated Silicone Strips Either Won’t Fit or Are Too Loose. Aside from Using Rtv Silicone, What Other Options Do I Have?
For large-scale equipment, significant tolerances are indeed a common occurrence. To address this situation, we recommend the use of silicone foam. Unlike solid RTV, silicone foam exhibits exceptional compressibility and tolerance-accommodating capabilities. These properties enable it to conform to and fill gaps of different sizes while ensuring consistent sealing performance.
Our Products Are Intended for Export; Given the High Temperatures Typically Encountered Inside Shipping Containers, Is There a Risk of Issues Arising with the RTV?
This represents a typical risk associated with RTV materials. Within a sealed container, volatile byproducts generated by incompletely reacted RTV tend to volatilize at an accelerated rate. If your products are exported to high-temperature regions—such as Southeast Asia or the Middle East—the internal temperature of the shipping container during transit may exceed 60°C. Such high-temperature environments can trigger secondary reactions within the RTV, then lead to product contamination. However, our regular silicone, which undergoes a secondary curing process, is fully resistant to the high-temperature conditions encountered inside shipping containers.
Final Thoughts
Making the right choice is the first step toward the success of your project, but whether that choice ultimately yields positive results for your silicone project depends on the quality of the silicone material itself. As a manufacturer with over 20 years of experience in China, Legensilico offers comprehensive, one-stop services designed to ensure that your project—from material selection to completion—exceeds your expectations. We invite you to contact us today for a consultation!
