Axson F40 (currently marketed as Sika Biresin F40) is a two-component rigid polyurethane resin with low viscosity, no odour and minimal shrinkage. It reaches a hardness of 83 Shore D and allows demoulding in just one hour, making it a highly efficient working tool for manufacturing rigid two-part moulds, workshop tools and high-precision structural parts.
Technical specifications
| Parameter |
Value |
| Material type |
Two-component rigid polyurethane resin |
| Cured colour |
Blue |
| Shore Hardness |
83 D |
| Mix ratio (by weight) |
100 A : 20 B |
| Working time |
6 minutes |
| Demould time |
1 hour |
| Maximum depth per layer |
Up to 10 cm |
| Kit contents |
1.2 Kg |
What it is used for
Axson F40 excels in applications where a rigid, high-precision part or shell with fast cure is required. Its low viscosity allows it to fill complex geometries without voids or bubbles, and its odour-free formulation makes it easy to work with indoors. It is also used as a backup layer in lamination processes over epoxy resins, or as a block casting for sections of up to 10 cm depth per layer.
- Manufacturing rigid two-part moulds for casting silicone
- Backup layer over epoxy resin laminates in composite processes
- Block castings of up to 10 cm depth per layer
- Brush or spatula application thickened with Gel de Sílice AT2
- Manufacturing high-precision workshop tools, jigs and fixtures
- Functional parts requiring high hardness and mechanical strength
- Rigid prototypes in product development processes
How to use it
- Prepare the surface and mould. Make sure the mould or substrate is clean, dry and free of dust. Apply a release agent if you are going to pour the resin into a reusable non-porous mould.
- Condition the components. Bring both components (A and B) to workshop temperature, ideally between 20 and 25 °C. If the parts have been stored in cold conditions, allow them to return to temperature before opening the containers.
- Weigh accurately. Mix at a ratio of 100 parts component A to 20 parts component B, by weight. Use a scale with a precision of at least 1 g to respect the stoichiometry and ensure correct cure.
- Mix thoroughly. Stir with a spatula or rod for at least 60 seconds, scraping the material from the sides and bottom of the container. If you need a thicker consistency for brush or spatula application, incorporate Gel de Sílice AT2 at this point.
- Apply or pour. You have a working time of approximately 6 minutes. Act quickly but without rushing: pour in a thin stream to minimise air entrapment, or apply with a brush in successive layers if you are building a shell.
- Allow to cure. Demoulding takes place at around 1 hour at workshop temperature. Avoid moving or handling the part before that time to prevent internal stresses.
- Demould and finish. Once demoulded, the part can be machined, sanded or painted. Full cure and final properties are achieved after 24 hours at room temperature.
Important notice — Polyurethane resin (isocyanate): The components of this system contain isocyanates. Always work in a well-ventilated space and wear nitrile gloves, safety goggles and, if ventilation is limited, a respirator with combined A2/P2 filter. Avoid contact with skin and eyes. Keep containers tightly closed when not in use to prevent moisture absorption by component B, which can cause foaming or improper cure.
Usage tips
Working time management
With only 6 minutes of working time, prior organisation is essential. Have the mould ready, the scale zeroed and all tools within reach before you start mixing. If you are preparing several consecutive batches, work with small containers in series: never prepare more material than you can apply within that time. Ambient temperature has a direct effect: above 25 °C the working time shortens; below 18 °C it lengthens, but the total cure also slows down.
Thickening for brush or spatula application
If you need to apply the F40 on vertical surfaces or as an outer shell of a mould, the liquid mix may be too fluid and run before gelling. Add Gel de Sílice AT2 to the already homogenised mix to give it thixotropic body without affecting the cure. For decorative effects or metallised replicas, you can also add Polvo de Aluminio Carga Metálica to the final layer.
Block castings and exotherm control
F40 accepts castings of up to 10 cm depth per layer, making it particularly useful for solid mould bodies. However, the greater the mass of mixed material, the greater the exothermic reaction. In thick castings, make sure the mould can withstand the heat generated and, if there is a risk of deformation, divide the casting into successive layers, waiting for each one to gel before pouring the next.
Frequently asked questions
Can I use this resin to make rigid two-part moulds?
Yes, it is precisely one of its main applications. Axson F40 offers a hardness of 83 Shore D, low shrinkage and demoulding in one hour, making it an ideal material for rigid shells of two-part moulds into which silicone or other flexible materials will subsequently be cast.
Do I need a release agent when working with this resin?
Yes. Rigid polyurethane resins tend to adhere to many surfaces, especially porous or rough ones. It is always recommended to apply a release agent to the mould or substrate before pouring. On porous surfaces such as plaster or gypsum, apply several coats of sealer before the release agent.
Can I mix this resin by hand or do I need special equipment?
Manual mixing with a spatula or rod is perfectly valid for most uses with Axson F40. It is important to mix thoroughly for at least 60 seconds, scraping the material from the sides and bottom of the container. For large volumes or series production, a low-speed electric mixer can make the process easier, but it is not essential.
What happens if I do not follow the exact mix ratio?
An incorrect ratio results in incomplete or defective cure: the part may remain sticky, soft or brittle. The 100A:20B ratio must be weighed, not measured by volume, as the two components have different densities. Always use a digital scale with a precision of at least 1 g.
Can I pour this resin in successive layers?
Yes. Axson F40 supports the layer-by-layer casting technique. To ensure adhesion between layers, pour the next one when the previous layer has gelled but is still in the process of curing (between 20 and 40 minutes after mixing, depending on temperature). If the previous layer is already fully cured and cold, lightly sand the surface before pouring the next one.
Is the resin compatible with platinum-cure silicones?
Once fully cured, Axson F40 is compatible with addition-cure (platinum) silicones. What can cause problems is contact during curing: if the resin has not yet finished curing and comes into contact with a platinum silicone without a release agent in between, surface inhibition of the silicone may occur. Always apply a release agent or barrier lacquer to the F40 mould before casting platinum silicone.
Can I machine, sand or paint the part once cured?
Yes. After 24 hours at room temperature, Axson F40 reaches full cure and can be machined, drilled, sanded, milled and painted without issue. The blue colour of the cured material makes it easy to detect unworked areas during finishing.
Is this resin suitable for parts in contact with food or for medical use?
No. Axson F40 is an industrial and technical resin; it is not certified for food contact or for medical or dermal applications. For those specific uses, consult the Feroca technical team to find the appropriate material.
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