How to finish my printed horn

Warning and Disclaimer

Drying your painted speakers or horns at excessively high temperatures or/and use of incompatible products can irreversibly damage them.

Unlike car bodies, which are typically made of separate, non-glued parts that can expand or move under high temperatures and are often painted with 2K paints designed to cure chemically and withstand such heat,
speakers and horns are complex, glued, hermetic assemblies made of various materials, including different types of wood, printed parts, and adhesives. These components expand and contract differently when exposed to heat.

Rapid artificial drying can cause:

• Deformation: Warping and distortion of the speaker or horn.

• Cracking: Damage to the glue joints between piece of woods, resulting in paint cracks at joints, which may appear immediately or several months after the painting process.

Professional painters who specialize in audio equipment use controlled drying processes tailored to the specific materials and thickness of each component. Over-drying is a common mistake with severe consequences.

We strongly advise against using high temperatures to speed up the drying process, including direct sun. Proper drying conditions are essential for the longevity and performance of your speakers or horns.

Traditional 1K painting are design to dry at temperatures around 20/25°C, 30°C maximum, while some car parts are dried at much higher temperatures (60-70°C), often with 2K paint design for.

Professional audio painters typically use short, controlled drying times based on the paint or/and varnish thickness and chemical properties.

To minimize the risk of cracking, we also recommend using primer and paint from the same brand.

If you are unsure about the correct drying process, please consult a professional painter with experience in audio equipment or follow our guidelines.

Protect your investment by following recommended drying procedures. AudioHorn cannot be held responsible for damage caused by improper drying methods.

For applications requiring extreme conditions, please contact us to discuss alternative materials.

1. Protect

Don’t forget to protect the hole screw with a false screw in PLA or screw that you will not use, otherwise you will not be able to use the screw’s hole at the end of the entire process.

You can ask us to provide it.

Protect yourself also with real mask like the AirGearPro M-500 or others, even when sanding raw PLA if possible.

2. Spray Putty/ Sealing primer

We start by sanding with P150 or P220 grit before applying 2 or 3 layers of Motip Spray Putty, making sure to apply each layer before it is fully dry to the touch, then you don’t have to sand; if a layer has already dried to the touch, sand and wait 24 hours before adding the next layer to avoid a chemical reaction.

Don’t forget to remove as much dust as possible.

In the US, you can find a better product, the 4-in-1 Raptor 1K Pro Primer, which is stronger and more protective, providing adhesion, sealing, and light corrosion resistance, while remaining a 1K product and not a true 2K high-build primer.

The final sanding can be done with P180 and then up to P600. Spray Putty is made to be sanded; it is not hard and does not provide as good adhesion for paint as the Raptor 1K Pro Primer does.

You can sand with these sanding sponges, without water:

They can be cleaned with water and liquid soap.

At this stage, the state of the surface must be perfect.

3. Primer and Sand

Skip this step if you use the Raptor 1K Pro Primer.

Here we will use a “filler,” such as the Motip Filler, also called a “high-build primer,” which allows better paint adhesion. We only do this step if the surface is already perfect thanks to the previous step.

Prefer applying thin layers of filling primer, applying each layer before it is dry to the touch, and sanding the last layer once it is dry using at least P400, typically up to P600 grit by hand.

The surface must be perfect at the end of this step.

4. Base Coat Paint

Use paint according to the brand’s instructions, ideally the same brand as the primer to avoid chemical reactions 6–12 months later, which can cause cracks or peeling if incompatible.

Apply thin layers with a regular aerosol paint. Two or three fine layers are usually enough.

You can sand the last layer up to P800 to provide enough adhesion for the clear coat.

5. Clear Coat / Varnish Protection

Still using the same brand, apply 2 or 3 layers of aerosol varnish to protect your paint once it’s dry.

• Motip Clear Varnish Matt

Dry

In every step, let product dry itself to official time and condition given by the brand, do NOT try to speed up it artificially in any manear.

Professional speed-up dryng in audio is done in a very controled and different way than car body parts, according to material, products used, thickness… See disclaimer section for more informations about it.

Warning about drying outside in direct sunlight: 1K paints are designed to dry at 25–30 °C. In direct sun, a black horn can reach 80–90 °C. Beyond the risk of dust contamination, such heat can cause 1K paints to crack or lose adhesion. While PLA offers the best torsional strength for indoor use (cf. PRUSA test), prolonged outdoor exposure to very high temperatures in direct sunlight is not recommended. If outdoor use is required, other filament types can be used.