RTV stands for room temperature vulcanizing. RTV silicone begins to cure immediately upon being exposed to air, as opposed to the curing agents in water-based sealants (for example, latex). It lends itself well to working as a sealer because it is water-repellent, adhesive and holds its shape. It’s most commonly used as a building sealer, especially in bathrooms and kitchens, where most caulking contains RTV silicone.
Natural rubbers are sticky and can easily be deformed in warm conditions. The process of vulcanization makes the rubber material more stable as it cures. This is achieved by introducing sulfur cross-links between the adjacent polymer chains. Unlike the vulcanization of rubber, the process of forming an RTV sealant takes place at room temperature.
The presence of water triggers condensation that forms cross-links between the adjacent polydimethylsiloxane chains (chains formed of silicon and oxygen atoms with two methyl groups attached). RTV sealant is stored in an airtight tube; when it’s squeezed out of the tube and comes into contact with the air’s moisture, a reaction is triggered that forces it to cure and harden.
RTV Silicone
RTV silicone is a type of rubber comprised of a two-component system and is available in a range of textures from soft to medium (between 15 shore A and 40 Shore). RTV silicone is a mild type of adhesive, but it does have a unique mix of properties that can create a gasket-like adhesive that glues two surfaces as well as providing a cushion.
These types of silicones can be cured with a platinum-tin compound catalyst. It can be applied at low temperature over molding, in molds used for reproducing and lens applications. The benefit of using silicone is that it can reproduce fine details and is suitable for a variety of both art- and industry-related applications including furniture, sculpture and aviation materials. Another benefit is that silicones can withstand thermal and mechanic stress, which makes them perfect for aerospace and aviation application.
RTV silicone adhesive is a ready-to-use sealant that can resist weathering and chemicals, often used for electrical insulation. The adhesive is often applied to surfaces when pourable sealant cannot be used.
RTV Silicone Gasket
RTV Silicone Gasket is a singular component vulcanizing gasketing compound designed to provide reliable gaskets for mechanical assemblies. The product cures upon exposure to room temperature air and will form a tough yet flexible silicone rubber gasket.
This product resists weathering and aging, with the ability to withstand the thermal cycle without hardening or cracking. RTV Silicone Gasket can be used to replace most cut gaskets or any dressing. It’s typically applied in sealing panels, window plates or on high-temperature equipment like oven doors.
Other Uses for RTV Silicone
Outside of construction, RTV silicone can be used in crafts, as it’s a light-duty adhesive that does not contain strong or harmful odors. It offers properties that many other craft adhesives don’t. Other craft adhesives are water based, so they will shrink as they dry and may be opaque when wet but translucent when dry. RTV silicone will always maintain its shape and stays translucent as it dries.
RTV silicone’s unusual properties are well suited to mold-making. It transforms from a jelly-like consistency to a rubbery consistency, which allows it to be poured around objects or applied to objects when making molds. The rubber properties are beneficial when cast items are being removed, as the material stretches and contorts so it will always return to its molded shape.
Disadvantages
One of the disadvantages of RTV silicone is that it can be more expensive and is prone to attracting dirt and residue. Because air moisture cures RTV, it needs to be applied to a surface rapidly, which can be difficult. The silicone is very thick and porous, so it needs to be degassed with a vacuum, so as to remove any air bubbles which could affect its application.
How RTV Silicone Cures
RTV silicone sealant reacts swiftly upon application. So long as the environmental temperature is at least 75 degrees F or 24 degrees Celsius, the seal will form within 20 minutes. If you are tooling the adhesion, it’s recommended to finish within 5 to 10 minutes from the moment you apply it; after that the sealant has already set.
The smaller the amount you apply, the faster the product will solidify. This is a benefit when being used to fill in gaps. It rarely takes longer than 24 hours to dry, but the maximum drying time is a 72-hour period. The exact time depends on the thickness of the sealant applied. The adhesive can continue to strengthen for up to two weeks after setting.