Infusion 101


Resin Infusion, although not a new science, has recently become more popular as better resin systems have come to the forefront. Resin Research has been one of the leaders in this field with the first commercial cycloaliphatic systems in the North American market in the early 80’s and with the first infusion of this chemistry in the early 90’s. With this expertise our continued research into modern production process has led us to the release in 2005 of our latest infusion system, the Composite Pro Resin line. Following this this the Pre-preg line, a 2015 product added longer pot life when necessary and better control when conditioning at higher temperatures. 

This line features three Bisphenol A based resins along with three unique cycloaliphatic hardeners. Each resin offers it’s own unique flexural cross section offering engineers specific modulus characteristics for each application. Three hardeners offer production management options specific to process cycling needs. Since all Composite Pro hardeners are 3 to 1 mix ratio these can be further mixed for custom application.

Other special features of this system include low toxicity, low vapor, low viscosity, excellent clarity, low blush, high gloss, low exotherm and excellent UV stability. As an infusion processing partner, this system contains a unique molecular lubricant modifier which, along with it’s low viscosity, provides for better wet out and added bond strength with interlaminate materials and substrates.

General Infusion Process

While individual processes vary, a general starting point in infusion methodology using the Composite Pro System generally follows along these guidelines.

1.Resin Conditioning

Conditioning of a high solids infusion resin generally requires bringing the resin temperature to around 80° – 100°F to reduce viscosity and to ensure proper resin/hardener mixture.  This shortens pot life at the higher temperatures and must be a consideration in the infusion strategy.

2. Flow Media 

There are many different flow media products available that give manufacturing choices in speed and final finish.  Flow media generally looks like a piece of plastic fencing and helps the resin flow into the part through small gap tunnels in the media itself (pictured below left). These vary according to the speed at which they allow the resin to flow.  There are also inner laminate flow media. Below right is one example, Lantor Soric. These products allow for a finished cored laminate in one shot.

3. Injection port strategy

The placing of injection ports should maximize resin mixture flow within time allotted for each part according to part size and desired cycle times. Generally each part will have it’s own wet out strategy dependant on resin/hardener conditioning, vacuum pressure, flow media and the geometry of the part.


4. Introduction of resin mixture 

Under vacuum introduce resin mixture. Resin mixture temperature parameters will be dependant on part size and geometry, injection port strategy, flow media and vacuum pressure. Flow speed and finished saturation should be based on approximately ½ of pot life.


5. Post cure 

Following injection completion an increase in temperature to 100°F to 150°F for 1 to 6 hours, depending on hardener speed used and part thickness, for initial cure. This should be followed by heating to 125°F to 225°F for a period of 2 to 6 hours for final cure. The post injection temperature ramp will accomplish maximum HDT.


Note: Part thickness, hardener used, resin conditioning, flow media, composite material, part geometry and desired cycle times all play a part in the balance of a successful infusion system. While these guideline are meant as an assistance to our customers, your own infusion strategy will take on it’s own unique parameters. Hopefully these guidelines will assist you in accomplishing a successful infusion strategy. 

For more information here is a link to a very good article on the subject: