To achieve consistent infusion, it is essential that both molds and dry stacks be heated - or even hot - prior to infusing epoxy resin systems which require temperature-dependent setting times for gel time. This is especially relevant with epoxy systems wherein their time of setting may depend on temperature.Use a gelcoat compatible with your resin system, or reinforcements with built-in flow features to facilitate resin wetting out more easily.Mix RatiosProper mixture ratio between resin and hardener is crucial for epoxy to cure properly. Careful measurements and mixing ensures the resin will transform chemically from a liquid state into an inert, high strength plastic solid form.Epoxy produces exothermic heat when curing, known as exothermism. Large volumes of epoxy mixed in an enclosed space such as glass or foam containers may generate enough exothermic heat to melt them and ignite combustible materials, so it is wise to use disposable plastic mixing containers when working with epoxy.Some processing procedures call for the use of moderate heat to accelerate an epoxy's curing time. Heating it too soon before reaching its initial cure can lower its viscosity and cause it to run or sag on vertical surfaces; additionally, this may cause it to bond to substrates it shouldn't (like wood or low density core material) instead.TemperatureEpoxy infusion requires resin with very low viscosity to enable it to be drawn through laminate by vacuum, creating an epoxy liquid that is easily sucked through laminates by vacuum. Standard epoxies tend to be thick and tacky at room temperature; however, special hardeners can thin down their viscosity sufficiently for infusion use. However, careful attention must be paid in regards to mix ratio as too much or too little hardener can have adverse results and even prevent cure! composite boat repair It is crucial that the mix ratio remains accurate since if either too much or too little hardener will impede cure time or even stop curing from even starting!Medical epoxy adhesives are designed for various medical applications such as bonding and potting. Biocompatibility and autoclave sterilization resistance are often essential. composite vehicle repairs Low-VOC and solvent-free adhesives typically meet these criteria while high temperature adhesives typically cure between 121-177degC (351degF), providing excellent thermal resistance. High temperature epoxy adhesives are commonly used in aerospace construction for bonding honeycomb panels, wings structures and structural components together while they're also great at tooling up composite panels using tooling processes or tooling methods.VacuumVacuum infusion uses the difference in atmospheric pressure outside and within an enclosed mold system to push resin into fiber stacks more efficiently, increasing fiber to resin ratio and producing an outstanding cosmetic finish.An effective VIP process relies on selecting reinforcement with care. Different materials and weave styles offer various levels of permeability to resin flow rates. Chopped strand mat is popularly used to produce fiberglass parts; however, its reduced permeability makes continuous strand mat a superior choice due to higher permeability and reduced crimping.Resin feed lines and inlet ports are another critical consideration in creating large projects, especially when using NASA-developed double (flexible) bag infusion (DBB) technique which utilizes rigid perforated shells interposed between 2 flexible bags in which individual controllable vacuum levels can be applied separately to each.ViscosityViscosity of epoxy resin is a critical factor for successful infusion processes. A typical two hardener epoxy system has an average mixed viscosity of around 200mPas which allows it to flow effortlessly through even dense fiber stacks.Temperature can also impact viscosity of epoxy. If not at its optimal temperature, epoxy can become viscous enough to double in viscosity and significantly slow its flow rate.Many epoxy resin systems can be pre-conditioned or heated to significantly decrease their viscosity, making the infusion process run at its ideal speed and producing seals without excessive vacuum pressure.