Can a black object be scanned without a spray?

Sometimes it can. The result depends on the material, the light source, camera sensitivity and the scanner mode. Blue laser systems can handle a range of dark and shiny surfaces without matting, but this does not guarantee the same result for any black object. A test on the critical area is required.

How is a matting spray different from ordinary paint?

A specialised compound forms a controlled thin matte layer and has specified application, removal or sublimation conditions. Ordinary paint may produce a thicker, non-uniform and hard-to-remove coating. For measurement work, a substitute is acceptable only after compatibility and its effect on geometry have been checked.

What if the object cannot be sprayed or taped?

Use geometry- or texture-based positioning, external references, frames, marked fixtures, a turntable or another scanning technology. For museum and valuable objects the preparation method is agreed with the owner or conservator before any contact with the surface.

3D blog:
note to the engineer

RangeVision
»
About us
»
Blog
»
How to prepare an object for 3D scanning: cleaning, fixturing and matting spray

How to prepare an object for 3D scanning: cleaning, fixturing and matting spray

How to prepare an object for 3D scanning: clean and fixture the part, choose a matting spray, apply it and check the result.

Preparing an object for 3D scanning does not always require the same amount of work. A matte part with complex, clearly discernible geometry can often be scanned without any additional effort. A mirror-like, transparent, dark or uniformly coloured surface often needs matting, while a large object or a part with repetitive geometry needs positioning markers. The right sequence is: assess the surface and the requirements for the result, clean and fixture the object, run a trial scan, and only then apply the preparation methods that are actually needed. Positioning markers are a separate topic; we cover them in our 3D blog.

Matting scanned objects: the short version

matting spray changes the optical properties of the surface: it reduces glare, lowers transparency and creates a uniform layer that the scanner recognises more easily
the matte coating becomes part of the measured surface: for geometry control its thickness and uniformity must be proportionate to the tolerance
before treating a valuable, painted, porous or chemically sensitive surface, test compatibility on an inconspicuous area

A black glossy plastic part before and after applying a matte layer

Why the surface needs preparation before 3D scanning

A 3D scanner derives the geometry of an object from the light pattern projected onto it. Cameras capture the distortions of that pattern, and the scanner software reconstructs the surface shape from them. If the pattern is not clearly visible on the surface, part of the data is lost or becomes noisy. This article deals with scanners that work with a projected pattern (structured light and laser ones); where the requirements differ, this is stated separately.

Typical problem cases:

polished metal and glossy paint produce bright glare;
a mirror re-reflects the projected light pattern, which adds noise to and distorts the point cloud;
a transparent material lets light through and refracts it, and may not be visible to the scanner at all (for example, PA polyamide parts printed on a 3D printer);
a black surface may return too little light to the cameras for the true geometry to be determined.

Matting helps to obtain a surface on which the projected pattern is clearly visible. But a matting spray is not always necessary and is sometimes harmful. So the starting point is not spraying the part or covering it, but diagnosing the reason that prevents scanning.

Smartphone body after matting and the STL model obtained by scanning

A smartphone body with a matte layer applied and the STL model produced by scanning

When an object needs matting

Even if the scanner manufacturer claims the ability to work with dark and shiny surfaces without a spray, that does not remove the need for a trial scan. For example, for the laser models RangeVision Helix and RangeVision Fenix this capability is stated on the official pages, while the stationary RangeVision PRIME with its ultra-bright blue structured light scans dark objects well, but mirror-like, glossy and transparent surfaces may still require a matting spray — it is included in the kit.

The result still depends on the material, curvature, viewing angle and the required data completeness. For mirror-like and transparent objects matting may remain necessary. And even when a scanner does handle a mirror-like surface (Helix, for instance), there may be more noise and deviation, and the result may be less accurate, up to exceeding the tolerances.

Scanning dark and glossy objects with the RangeVision Helix handheld laser 3D scanner without matting spray

The RangeVision Helix handheld 3D scanner scans dark and glossy objects in one pass, while a structured-light scanner cannot do this without matting

Step-by-step preparation of an object for 3D scanning

1. Define the task and the requirements for the result

Before you start, determine:

Which surfaces must be captured in the model.
What the data will be used for — visualisation, 3D printing, reverse engineering or geometry control.
Which areas are critical.
What tolerance or level of detail is specified.
Whether coating, adhesive and subsequent cleaning are acceptable.
Whether the colour and texture of the surface must be preserved.

If the goal is geometry control with a tight tolerance, the spray layer cannot be considered neutral. Manufacturers of specialised compounds quote different coating thicknesses for different products. For example, the current AESUB aerosol range states values from 2 to 20 µm depending on the composition. This is not a universal characteristic of all sprays, but an indication of why the specific product has to be chosen for the task. The fine-dispersion RangeVision spray has a standard layer of 4−8 µm, but in practice it can reach 10−20 µm depending on the dosage. One layer is sometimes not enough, while an inexperienced user easily applies too much.

2. Inspect the object and choose the accessible areas

Determine whether the scanner can be moved freely around the part (or mounted on a tripod next to it) and whether the required surfaces can be seen:

end faces and the back side;
deep slots and undercuts;
internal surfaces;
areas next to supports and fixtures;
transitions between large areas.

If part of the surface will be hidden once the part is placed on the table or in the fixture, plan several positions in advance. Each position needs common geometry or reference points so that the data sets can be aligned. Often only the required area is needed rather than the whole object: the area being reverse engineered, the area for which a mating part is being designed, or the area under inspection.

3. Clean and dry the surface

Dust, chips, droplets, oil and loose contamination become part of the scan. The system captures not only the part but also the foreign layer, which can add problems and complexity both for inspection and for reverse engineering.

The cleaning method is chosen according to the material and the plant procedure. A solvent or degreaser must not be applied by default to a painted, polymer, composite or porous surface, especially when it is the surface of a museum exhibit. Compatibility of the agent is first tested on an inconspicuous area.

After cleaning, the surface must remain stable throughout the scan. If oil, condensation or dust reappears, eliminate the cause instead of applying a thicker layer of spray.

4. Fixture the object rigidly without deformation

The part must not move relative to the markers, the turntable or the external reference frame during scanning, while the clamp must not change its shape. This is especially important for thin-walled parts, rubber, soft plastics and long components.

If the object has to be turned over, define the overlap areas and the method of aligning the individual scans in advance.

5. Prepare the working area

Remove moving objects and foreign reflective surfaces from the working area. Check:

enough space for the operator to move with the scanner in hand, or for placing the scanner on a tripod in front of the object;
stability of the tripod, table and fixture (for stationary scanners);
absence of vibration;
lighting and temperature within the scanner manual's limits and stable;
power supply and computer connection;
whether the scanner cameras have warmed up, if that matters (if the user manual requires it, or if you want maximum accuracy from the equipment);
whether the scanner has been calibrated for the current conditions.

For structured-light systems, direct sunlight and rapidly changing lighting can impair geometry capture. Laser models with optical filters are less sensitive to ambient light, but the operating conditions must still match the data sheet of the specific device.

6. Run a trial scan

A trial capture shows whether additional preparation is needed. Check:

whether gaps remain on dark or shiny areas;
whether noise appears around glare;
whether positioning is maintained;
whether small features are recognised;
whether the object changes under the clamp or temperature;
whether the working distance and field of view are set correctly.

If the data is stable, do not complicate the process.

How to choose a matting spray for 3D scanning

A matting spray creates a thin layer with uniform light scattering. On the RangeVision accessories page such compounds are recommended for dark, transparent, mirror-like and glossy surfaces and polished metal when working with optical scanners.

RangeVision matting sprays

Main types of matte coatings

For valuable, irreplaceable or collectible parts and objects we recommend a simple rule: before scanning, test any spray on an inconspicuous area of the object or on a sample of the same material. This greatly reduces the risks.

Medals and awards scanned with a matte coating

Museum exhibits must not be touched with bare hands, let alone coated

When choosing, check the technical data sheet and the safety data sheet of the compound: compatibility with the material, layer thickness, time until the coating is ready for scanning, working window, removal method, ventilation and personal protective equipment requirements. Household powders, paints and developers can produce a scannable surface, but without verified characteristics they cannot be considered equivalent to a metrology-grade coating.

How to apply a matting spray

Seal holes, seating surfaces, threads, connectors and any areas where the compound must not get.
Test compatibility on an inconspicuous area.
Shake and prepare the compound according to the manufacturer's instructions.
Apply several thin overlapping passes rather than one thick layer.
Hold the can at the distance and angle specified in the instructions for the specific product.
Pay particular attention to recesses, edges and transitions, without creating runs.
Wait until the coating is ready for scanning.
Run a second test and assess the uniformity of the data.

Whiteness alone is not a criterion of quality. What matters is uniformity, absence of gloss and a minimally sufficient thickness. Runs can smooth fine relief and change dimensions, so the urge to cover everything thoroughly makes the result worse.

Never leave an object matted if it is valuable! Make it a rule: scanned — remove the layer. The longer the layer stays on the surface, the greater the chance of penetration into pores and of unexpected chemical and temperature reactions.

If both spray and markers are needed, a uniform coating is usually created first and the markers are placed afterwards: spraying over the markers can impair their recognition. The adhesion of the stickers to the specific coating must be verified.

How to verify the preparation before the main scan

Preparation is complete when the test pass confirms four conditions at once:

Data completeness. There are no systematic gaps on the required surfaces.
Positioning stability. The system does not lose tracking along the planned route.
Geometry preservation. The coating, the fixture and the markers do not cover critical features or deform the object.
Fitness for the task. Data density and surface quality are sufficient for further processing but not unnecessarily high.

For measurement tasks it is useful to scan a reference area before and after applying the coating, or to use a sample of known geometry. This assesses not only the visibility of the surface but also the effect of the preparation on the result.

Scanning a coin: without matting, with a matte layer, after cleaning and the resulting 3D model

Scanning a coin: before matting, with matting, after cleaning, and the resulting scan

Common mistakes when matting objects

Spraying every object
Extra coating increases working time, material consumption and the risk of changing the geometry. A trial capture comes first.

Applying a thick white layer
Excess coating masks small features and shifts the measured boundary outwards. A minimal uniform layer sufficient for stable geometry capture is what is needed.

Ignoring the subsequent cleaning
The compound may remain in threads, pores, slots and on rough surfaces. The removal method must be determined before application.

Starting a full pass without a test
A short trial scan reveals an unsuitable coating, a lack of markers, hidden areas and wrong settings faster, and costs far less than re-digitising the whole object.

Matting spray residue embedded in the surface of a plastic model after scanning

After scanning a plastic model, the spray residue had penetrated the surface so deeply that it could not be washed off

FAQ — common questions about matting

No. Matte surfaces with stable reflection are often scanned without any coating. The spray is used when glare, transparency, low reflectivity or surface non-uniformity cause gaps and noise. The decision is made after a trial capture, taking into account the scanner type and the requirements for the result.

Conclusion

Preparing an object for 3D scanning should eliminate the specific cause of data loss. A matting spray reduces glare and reflections, fixturing preserves the geometry, and a trial pass verifies the whole setup before the main capture. Positioning markers are covered separately in our 3D blog.

For a single technical task a short cycle is enough: cleaning, fixturing, test, local matting, re-check. A large object or metrological inspection requires a separate procedure covering the coating thickness, the reference network and the acceptable effect of preparation on the measured surface.

If the object cannot be treated safely, or the requirements for the result are not yet formalised, the method can be tested on a demonstration fragment, or the task can be handed to RangeVision 3D scanning specialists.