Brass powder is a fine-grain metallic filler that is mixed with resins, pastes and other materials to produce parts with genuine metallic content, greater density and the characteristic golden finish of brass. It is the straightforward option when you need that real metallic weight and appearance without resorting to paints or surface coatings.
Technical specifications
| Property |
Detail |
| Base material |
Brass (copper-zinc alloy) |
| Format |
Fine powder |
| Colour |
Metallic yellow gold |
| Main use |
Filler for resins, pastes and composite materials |
What it is used for
Brass powder is incorporated as a filler in the liquid phase of polyurethane resins, epoxy resins and other casting systems to add mass, weight and genuine metallic appearance to the finished part. It is also used in surface gel coat layers to achieve a golden finish without the need for metallising.
- Decorative and sculptural pieces with real metallic weight and feel
- Replicas and reproductions of antique metal parts
- Special effects and props with a brass appearance
- Metallic gel coat layers in open moulds
- Prototypes and scale models with a premium metallic finish
- Designer jewellery, art pieces and craft work
- Joint filling and restoration with a metallic look
How to use it
- Prepare the base resin (polyurethane or epoxy) following the manufacturer's instructions, without mixing the two components yet.
- Add the brass powder to component A or to the already prepared resin mixture, at an approximate ratio of between 10% and 50% by weight depending on the desired effect. The higher the proportion, the greater the weight and metallic opacity.
- Stir thoroughly with a spatula or mixer until the powder is evenly distributed throughout the resin.
- Add the corresponding hardener or catalyst and mix according to the instructions for the chosen resin system.
- Pour or apply the mixture into the mould before it begins to gel. For a gel coat effect, apply a thin layer to the mould walls and allow it to partially cure before pouring the core.
- Once the part has cured, demould it and, if desired, buff with fine steel wool or apply a polishing wax to bring out the metallic shine of the brass.
Usage tips
Proportion and density
You can freely vary the amount of brass powder incorporated into the resin. At low proportions (10–20%) you will get a subtle metallic appearance and moderate weight; at high proportions (40–50%) the part will gain notable density and the finish will be very opaque and metallic. Bear in mind that the higher the filler load, the more viscous the mixture will be and the working time will be slightly reduced. If you need to compare with other metals, bronze powder gives warmer, more reddish tones, copper powder a dark coppery finish, and aluminium powder a silvery, lightweight result.
Post-cure surface finish
Brass powder does not oxidise as quickly as copper, but over time it can develop a natural patina that many users deliberately seek for aged effects. If you prefer to maintain the initial golden shine, protect the part with a matte or gloss lacquer once polished. To achieve maximum metallic shine, sand progressively with wet-and-dry paper in fine grits (400 → 800 → 1200) and finish with a metal polish.
Compatibility with resins
Brass powder is compatible with polyurethane and epoxy resins. Mixing it with water-based acrylic resins is not recommended, as the interaction with water can cause unwanted oxidation of the metallic filler and affect the cure. For surface layers with a metallic effect in acrylic systems, consult Feroca's specific solutions. Remember that if you use a hollow glass microsphere filler alongside the brass powder, you can modulate the final weight of the part without sacrificing the metallic appearance.
Frequently asked questions
What proportion of metallic filler should I add to the resin?
There is no single proportion: it depends on the effect you are looking for. For a light metallic finish, 10–20% by weight relative to the resin is sufficient. For parts with real metallic weight and opacity, you can go up to 50%. With brass powder, start at 20–30% and adjust based on the working viscosity and the visual result you need.
What types of resin is this metallic powder compatible with?
Brass powder is compatible with polyurethane and epoxy resins. Its use in water-based acrylic resins is not recommended, as moisture can cause oxidation in the filler and alter the curing of the system.
Can it be used on the surface only, or does it need to be mixed throughout the whole mass?
You can use it either way. The gel coat technique involves mixing brass powder with resin and applying it in a thin layer over the mould before pouring the core. This achieves the metallic effect on the surface only, saving material. If you mix it throughout the whole mass, the part will have metallic weight and appearance throughout its entire cross-section.
How do I achieve maximum metallic shine on the finished part?
Once the part has cured and been demoulded, sand progressively with wet-and-dry paper (400, 800, 1200) and finish with a metal polish or a polishing cloth. Brass powder, being present at the surface of the part, responds very well to polishing and gives a characteristic golden shine.
Does the metallic powder oxidise or change colour over time?
Brass can develop a dark golden patina over time, especially in humid environments. If you want to preserve the bright golden appearance, protect the finished part with a finishing lacquer once polished. If you are looking for an aged effect, you can let the natural patina develop or accelerate it with specific products.
Can I mix different metallic powders to obtain other colours?
Yes. Mixing brass powder with copper powder gives warmer, more reddish tones; combining it with aluminium powder lightens the tone towards a pale gold. Experiment in small quantities before preparing the final mixture.
Are there any safety precautions when handling metallic powder?
Yes. Fine metallic powders can be easily inhaled, so it is recommended to work in a ventilated space and wear a particulate respirator (FFP2 or higher) when weighing and mixing. Avoid prolonged contact with skin and eyes. Consult the product safety data sheet for complete information.
Can this metallic filler be used to increase the weight of a part without changing its size?
That is exactly one of its most common uses. By incorporating brass powder into the casting resin, the final density of the part increases proportionally to the amount added. It is a common technique in replicas, props and sculpture when you need to simulate the weight of a real metal part.
