Frequently asked questions

Yes, Ironbark Composites has clients across Australia and internationally. We regularly send fibreglass cloth, carbon fibre cloth and aramid (Kevlar) fabric to clients in New Zealand, Singapore, China and India. There are plenty of inferior products around and quality fibreglass supplies can be hard to find.

Contact us and we’ll happily arrange to send our products to destinations in Australia and overseas.

Basically there are two methods of laminating when working with fibreglass, carbon fibre and Kevlar – hand laminating and vacuum bagging.

Hand laminating is the process of applying resins to the fabric and working it by hand. While quite sufficient for some projects, hand-laminating is not suitable for others because it allows too much variation in cloth-to-resin ratios and compromises strength and finish.

Vacuum bagging involves laying up the fabric and epoxy and then sealing it within a plastic film or bag and using a vacuum to extract the air within the plastic. The uniform pressure created by the vacuum distributes the epoxy evenly throughout the fabric, ensuring an even finish and high strength with minimum weight. Vacuum bagging is ideal when creating high-end products such as boats, car parts and even surfboards but is not necessary for all projects.

If you’d like to know more, get in touch with our vacuum bagging experts and we’ll run you through the vacuum bagging process and we can also provide vacuum bagging pumps and other equipment.

That answer depends to a degree on the project you’re working on and the fabric you’re using. A fibreglass resin might not be the best option for carbon fibre cloth, and vice versa. Ironbark Composites provides a range of laminating resins, infusion resins, gelcoats and foaming epoxy.

Get in touch, explain your project and we’ll advise you on the best resin for the job.

There’s not really any difference except that Kevlar is a type of aramid. Aramid is a material and Kevlar is one of the brands within that range or materials. So when you’re buying Kevlar fabric, you’re actually buying a brand of aramid. We provide a range of aramid materials, including Kevlar, Twaron and Technora.

Short answer – yes! Long answer – yes, we have an expansive range of tapes and braids, including fibreglass tape, carbon tow, carbon braids, Kevlar braid (aramid) and flat braid, rovings, unidirectional tapes. Whatever your project, we have it covered.

Enhancing resin infusion with peel ply resin breaks

When using the resin infusion process to make a composite part, the combination of a peel ply resin break:

• Improved control over the resin distribution pattern
• Reduced resin wastage
• Reduced risk of resin trap overflows
• Less vacuum tubing wastage and reduced resin trap cleaning.

The purpose of the resin break is to significantly slow down the speed of resin movement as soon as the resin has filled to the edge of the laminate.  This allows the laminator more time to confirm that the laminate is completely filled.

The general arrangement is illustrated below.  The layer of peel ply typically placed between the top surface of the laminate and the flow medium is extended beyond the edge of the laminate by a distance that might range from 30 mm (1¼”) for a small part through to 100 mm to 150 mm (4” to 6”) for a large part such as a boat hull or wind blade.  Note that for any particular part, the width of the peel ply break should be uniform around the perimeter.  At intervals, small areas of peel ply are cut away and the perimeter spiral-cut vacuum line under the bag film is interrupted to match the notches in the peel ply.  For small parts, a 75 mm (3”) gap between each section of perimeter vacuum line appears to be sufficient to isolate one section of vacuum line from the adjoining one.  For large and complex parts, better process control could be achieved by increasing the gap between sections to about 300 mm (12”).  At this time, we can’t be completely specific about optimum gaps and welcome feedback from hands-on laminators using these techniques.

Each section of perimeter vacuum line must have its own exit from the vacuum bag.  This external vacuum tube can be fitted with a valve as shown, or be of sufficient length to allow it to be clamped off without stressing the penetration through the bag.  If the resin trap has sufficient vacuum connections on its lid, each of these external lines can be run directly to the resin trap (left hand illustration below).  If the resin trap lid does not have sufficient connections, external lines may be grouped together via Tees, as in the right hand illustration.  Having each vacuum line run directly to the resin trap allows optimum process control.

Vacuum pumps for resin infusion

We often supply our resin traps and controls to customers who already have a vacuum pump, or who wish to reduce the overall equipment cost by buying a second hand vacuum pump. As long as a suitable pump is selected and appropriately connected to the resin trap, the end result should be fine.

Suitable type of vacuum pump

While they need regular oil changes and the occasional blow down to remove surface dust, the type of pump most suited to resin infusion applications is the oil sealed, single stage rotary vane vacuum pump. These are usually readily available from vacuum pump manufacturers offering pumps for general industrial applications.

Although tempting because of their low cost, pumps to be generally avoided for composites use are the high vacuum rotary vane pumps typically used for servicing refrigerators and air conditioning systems. These refrigeration industry service pumps are designed for short running hours at high vacuum. In composites use, they tend to have a short life and are prone to discharging oil vapour from the pump exhaust when run at poor vacuum, e.g., if the bag leaks or a large bag takes a long time to pump down. Apart from making the work environment unpleasant, the vapour discharge can contaminate the mould surface and the laminate with an oil film.

Note that the .. after the model initials are most often numbers indicating the nominal pump capacity in m3/h at 50 Hz motor speed (but this is not always the case, so check the maker’s data sheet). The suffix following the pump capacity numbers usually designates the ultimate vacuum capability of the pump.

Laminates < 1 square metre or 10 square feet – pump capacity 4 m3/h to 5 m3/h (2.5 cfm to 3 cfm)

Laminates < 20 square metres or 215 square feet – pump capacity 8 m3/h to 10 m3/h (4.5 cfm to 6 cfm)

Laminates >20 square metres or 215 square feet – pump capacity 20 m3/h to 30 m3/h (11.5 cfm to 18 cfm) per resin trap*, or per 100 square metres (1,100 square feet) of laminate

The recommended pump capacity suits resin traps with ½” (12.7 mm) to ¾” (19 mm) pump connections. Unless a large volume resin trap with an appropriately enlarged pump connection, applying much more than about 30 m3/h (18 cfm) tends to be wasteful and may create considerable noise through the vacuum regulation valve (if one is fitted).