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Composites made modern.

What is fiRST®?

fiRST®- Fiber Infusion Reusable Silicone Technology. 

The latest open/closed moulding process for composites manufacturers in the UK.

Purpose Led Innovation

Open & closed moulding made modern for composite manufacturers UK. It’s time to streamline your processes, reduce costs and improve your composites operations.

Our Mission

We provide cost-effective hardware and innovative technologies that challenge conventional open & closed moulding production methods, offering sustainable solutions that drive efficiency and profitability for companies operating in composites UK.

A UK award-winning composites manufacturing system evolved from 14+ years worth of experience.

machine head topgear silcon 6 suitable for composites manufacturers UK
vacuum membrane production from local composite companies UK

Welcome to the UK’s leading reusable vacuum membrane technology and production house. We offer the closed-mould and composite plastics fraternity with the world’s most cost-effective and efficient technology. We support composite manufacturers across the UK and globally optimise for improved production, cost and waste output. 

Process Benefits for Composite Companies

Benefits listed are expected for open and closed moulding composite companies UK. Although we predominately promote the advantages such as efficiency and waste reduction, our system boasts a vast range of unrivalled benefits to challenge current traditional tooling methods.

Rapid Fill Times

We match or improve current moulding fill times.

Self Releasing

No requirements for release agents to support demoulding.

Lower Cost

Lower net cost due to reusable nature.

High Reapplication Use

Get 600+ parts made per membrane.

Complex Designs

Complex negative draft designs are easily accommodated.

Reduced Maintenance

Membrane requires little lifetime maintenance.


The most environmentally friendly method in the composites space.

Improve Employment

Cleaner working environments & process becomes more appealing to staff.

Output Increased

Optimise your production to support a more efficient turnaround of parts.

consumable bagging from composite companies UKreusable vacuum bagging from composites manufacturers UK

Future Proof Your Business.

Let’s be real, moulding for composite manufacturers is a messy, smelly, time and waste-heavy process. But, imagine if you were able to produce your composites parts in a cleaner, leaner, efficient way (all while maximising profits and saving the environment too)… Well, we’ve got good news. Alan Harper Composites exists entirely to offer this innovation to your open/closed moulding business. It’s time to mould smarter. Improve your system for you and your employees, whilst maximising profits for your business. Get in touch with our UK team today. 

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Years of Dedicated Experience

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Specialist Products

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Successful Projects

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Asked Questions

Changing the composites space for the better, one reusable silicone vacuum membrane at a time. 

We firmly believe that reusables can benefit most composite companies in the UK and further afield, particularly those using polyester or vinylester materials, given the significant reapplication cycles achieved. In just a few cycles, the savings in time, materials, and labor typically offset the initial manufacturing costs, leading to long-term profitability and increased production output. A recent case study from our partners Aerontec in South Africa demonstrates an excellent example of our system advantages. See how other composite manufacturers in the UK are benefitting from our technology on our blog

How to get started...

If you're considering implementing our system, we encourage you to reach out to us with your moulding requirements. We'll work closely with you to understand your needs and provide a non-obligatory quotation tailored to your specific project. Throughout our engagement, we prioritise clear and open communication to ensure you have full confidence in the process and know exactly what to expect before making any commitments. Your success is our priority, and we're here to support you every step of the way.

We can support composite manufacturers in the UK with the right guidance for reusable membrane preparation. If you have any questions or concerns please contact us
1. Calibration

The face mould should be calibrated accurately using sheet wax to the final thickness design of the part. It's important to familiarise yourself with how to calibrate using sheet wax correctly. This sometimes is too expensive to do and can be carried out more economically but less accurately using a grp moulded part. In this case, the part rear face needs to be smoothed over to flatten any sharp points and edges and free from any loose fibres.

Note – The problem using a moulded part is that internal corners may be bridged and therefore be extra thickness and inaccurate. As the sprayed reusable vacuum membrane does not shrink it will naturally copy any inaccuracies in the calibration into itself.

2.Clean & Smooth

The surface of the calibration does not need any release agents applied simply needs to be clean and as smooth as possible.

3.Cure & Prepare

If the calibration is done using a moulded part then it must be well cured (made and left to cure for at least 4 days) and trimmed to final dimension . If, when replacing into the face mould, there are small gaps at the trimmed edge then these will be filled with non-sulphur modelling clay. Other clays which usually contain some sulphur are NOT suitable . If the calibrated part is made by hand lay then smooth over its cured B face with 280 sandpaper and if necessary gaps and large surface roughness can be flattened using body filler and rubbed smooth.

4.Flange Specs

The flanges of the mould should at least 100 mm wide (130mm ideal) and be left clean ready for the normal reusable vacuum membrane calibration for the seal and mini vacuum channel.

5.Flange Preparation

All flanges should not have sharp corners if they are designed with changes in height or direction. See picture example of correct flange set up. Any changes in a direction up or down should be made through at least a radius of 25mm or more . The greater the radius the better. 


Standard Polyester and Vinyl Ester

While standard polyester and vinyl ester clients have achieved over 600 cycles, deep draw and narrow shapes in a membrane typically result in a shorter service life, especially when solid silicone is involved. The issue arises from styrene attack coming from both sides of the “V” and meeting in the middle. The longer evaporation time of styrene from the silicone membrane in such sections leads to whitening through constant use, resulting in weakened, less elastic, and brittle membranes prone to fracturing. In such cases, applying Silcoset 153 over the surface can locally coat and strengthen the worn-out whitening sections, extending the membrane's longevity through repeated applications. Please note, higher exothermic temperatures in resin-rich corners common to deep V moulding designs accelerate this type of whitening.

DCPD-based unsaturated polyester resin

This significantly reduces the life of a membrane, shortening its usable cycle life to as little as 100 cycles or less. The chemistry of DCPD affects the membrane, evidenced by discolourization through whitening of the translucent membrane blue colour and loss of its self-release characteristics.


ACERS or Amine Cured Epoxy Resins

These pose challenges to high-quality silicone as the amines are absorbed and attack the membrane surface within only a few cycles. The number of cycles clients can achieve with ACERS depends on the individual epoxy and nature of the curing agents, typically ranging between 27 and 35 cycles. After this time, the cured laminate becomes very difficult to release from the membrane surface, eventually sticking so hard that the membrane tears or pits. Higher temperature cures exacerbate the longevity issue and the time from wet ACER contact to cure.

Our SILFLON coating solution is the recommended method for rejuvenating membranes worn down through high life cycles as well as DCPD and epoxy resins. Available in 125 and 510 g packaging, SILFLON is simply painted or sprayed over the worn-out surface and allowed to cure for at least 10 hours at ambient conditions. It is moisture-curing and requires no heat to accelerate. A 125 g bottle is sufficient for 0.7 m2 of membrane cavity moulding area.

Additionally we recommend the use of Marbocote SB4 release agent applied to the new membrane before production start and reapplied every 2-3 cycles. 

The most common error when using addition cure (platinum cure) 2-part silicone is applying the mixture onto contaminated surfaces. The main contaminants include:

  1. Any natural or synthetic rubber containing sulfur.
  2. Condensation cure silicone (RTV).
  3. Modelling clay like Plasticine, often sulfur-based or with tin/ amines. We suggest using our safe moulding dough that doesn't contaminate. 
  4. Under-cured polyester mouldings emitting styrene gas.
  5. Carbon Monoxide gas, even in minute ppm levels.


Before applying mixed silicone onto any surface, always conduct a small area test by pouring a small amount onto the work part and allowing it to cure. Heating with hot air can accelerate this test. If the cured silicone appears wet, oily, under-cured, or sticky upon removal, it indicates surface contamination. In such cases, sealing (e.g. with PVA release agent) and additional tests must be performed before proceeding with membrane manufacture using spray or brush methods.

After over a decade of experience, we advise all of our UK composite manufacturers to budget for 7 kg/m2 of total reusable membrane surface. While the main membrane typically ranges between 3 and 4 mm in thickness, this figure accounts for additional edge seal thickness and reinforced cloth areas, which may cover the entire surface. The 7 kg/m2 represents the combined weight of the mixed silicone, with 3.5 kg of Part A and 3.5 kg of Part B per square meter. Alternatively, if you intend to create a bladder, it is recommended to assume 4 kg/m2.

Let's illustrate our approach using a case study with Dartford Composites Ltd, showcasing their successful moulding of a rail carriage seat. This monolithic laminate, measuring 3 mm and composed of fire retardant resin, undergoes our Vacuum Pressure Infusion (VPI) process within minutes using a reusable vacuum membrane. With a fill time of under 8 minutes and minimal waste after a 2.2 kg mix pour, our process offers efficiency and precision.


Three key features contribute to the success of contouring the fiber within multiple corners before VPI:
  1. Combination Mat Fiber: Utilising a combination mat similar to the original Choramat Rovicore, we ensure full-weight glass in one ply. This glass layer, at 1200 g/m2, facilitates easy manipulation into three-dimensional shapes, requiring minimal tailoring and quick loading.

  2. Gel Coat Tack: The gel coat tack aids in adhering the glass laying into negative corners. Maintaining proper tackiness is crucial; if the gel coat dries too much, it becomes challenging to position the glass before vacuuming. In such cases, re-tackification is achieved through a mist spray of acetone.

  3. Specially Designed Membrane: Our membrane features additional thickness in internal corner shapes, providing semi-rigidity and acting as intensifiers. These regions assist in achieving perfect fiber pressure, mitigating the risk of bridging often encountered with conventional infusion consumable films. Despite the precise fit of our reusable moulded membranes, operators still play a crucial role in pushing down into corners as vacuum pressure builds. This ensures that the male membrane's detail is firmly secured in these critical areas, typically requiring about 30 seconds of operator attention. It's important to note that resin flow begins during this stage, deposited in the seat mould's bum area.

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