Matt clearcoats

Matt lacquered vehicles are in vogue. The silky shimmering or partly dull matt surface gives every vehicle a special touch and makes it stand out from the crowd of glossy painted cars. Repairing matte finishes, however, places special demands on repair shops.

Processing requires precise preparation and a great deal of manual skill. In addition, any processing errors can only be corrected with considerable effort. For what is commonplace with glossy clearcoats,
This is not possible with a matte finish: Here, neither sanding nor polishing is possible.

The painter literally only has one shot at it.

So that nothing shines after the repair.

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Even minor repairs are a challenge with matt paints.

With matt paints, it is not possible to polish out the smallest scratches on one side of the vehicle or to remove fingernail marks in the recessed grips. The result would be more or less glossy dots and streaks as optical defects on an otherwise uniformly matte surface.

MicroRepair and hatchet painting won’t work either, both of which would also degrade the overall appearance. To avoid this, the complete component is therefore always painted.

Depending on where the damage is located on the car, it may even be appropriate to completely repaint one side of the car.

Care and precision – the be-all and end-all for a perfect result.

The refinishing of matte surfaces is – both in terms of time and materials – more costly than that of glossy surfaces. But with good preparation, due diligence in the work and the right products, perfect results can be achieved.

Above all, precise work is important. Since even the smallest deviations in the mixing ratio of clearcoat, hardener, thinner and matting agent lead to deviations in the degree of matting, you should use
precisely mixing the quantities required for a full or partial coating using the scales.

The use of Standowin iQ enables precise weighing in. One hundred percent accuracy is also important for documentation and for possible later readjustment.

The effects of film thickness and drying on the matte coating.

Even before painting, it should be borne in mind that different film thicknesses have an effect on the appearance of the dried paint film. Therefore, the application must be adapted to the conditions.

  • Two "normal" spray passes may look different after drying than two "rich" ones.
  • Correct flash-off is important: To avoid "gloss pockets", the intermediate and final flash-off times specified in the technical data sheet should be precisely observed.
  • Even the method of drying plays a role in the repair of matt clearcoats. Air or forced oven drying have different effects on the gloss level. Oven-dried coatings usually turn out a bit shinier than air-dried ones.
  • Infrared drying should be avoided altogether.

Background knowledge.

How color perception and the impression of a matte surface are created?

Color impressions of an object are created via nerve impulses in the observer’s brain:
The human eye receives color stimuli via the retina, transmits them to the brain and thus triggers a certain color sensation. That part of the light spectrum which is reflected rather than absorbed by the surface of an object provides the data which our consciousness assigns to a particular color.

Reflection is also the reason why our eye perceives a surface as glossy or matte. Certain additives in the clearcoat increase light scattering to such an extent that the surface appears matte.

What influences the matte color tone?

influence the appearance and gloss level:

  • the layer thickness of the individual spray pass or. the total layer thickness,
  • the spraying method, for example bold or restrained, large or small gun spacing, single coats or cross coats,
  • the intermediate/final flash-off time and the color shade,
  • the temperature and type of drying (air or oven drying),
  • the cabin and material temperature during processing,
  • hardener and thinner.

The gloss level increases with the use of short hardeners and thinners, a higher spray viscosity, high film thicknesses and forced drying.

The gloss level becomes lower when using longer hardeners and thinners, low spray viscosity, low film thicknesses and air drying. Since humidity also influences the result, we expressly advise against air drying when repairing matt coatings!

From these reasons it is clear that the gloss level for a repair can only be determined by a spray pattern!

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Light reflection on glossy clearcoat (simplified illustration, since effect pigments also have a scattering effect, but only within the basecoat layer).

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Light reflection on matt clearcoat (matting additives contain spherical particles that have a strong scattering effect). The reflection is most uniform at a viewing angle of 60 degrees, which is why the gloss level for the automotive paint area is measured and specified at this angle.

What you should look out for with matt coatings.

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Since numerous factors influence the gloss level, it is not possible to make a binding determination of the gloss level. There are measurable differences even in the series production coating. In practice, this means that uniform results cannot be achieved under conditions that change daily in the paint shop. Therefore, a larger object should not be painted over several days and with different material approaches. For a uniform appearance, the coating should be applied as a compound.

In the case of matt coatings, dust inclusions cannot be polished out for technical reasons. In this case, repainting would have to be done including the base coat. Depending on the object, the color shade and the desired gloss level, we recommend finishing the coating first with a glossy Standocryl VOC Clearcoat.

Every refinish still contains solvent residues after drying. In the case of matt coatings, this means that the final gloss level is not quite achieved immediately after drying. Measurements show that the gloss level can still decrease by up to five percent within 14 days.

Treat fresh matt coatings in particular with the greatest care. According to the current state of the art, damage to the surface can only be removed by repainting. Any wetting, e.g. by cavity wax, adhesives or sealants, must be removed immediately with cleaning solvent. Do not use solvents!

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Make sample sheets.

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1. First determine the gloss level, then the color shade.

The gloss level has a significant impact on the appearance of the shade.
Therefore, first paint spray samples with different ratios of Special Matte to VOC-HS Clearcoat K9520. Start with mixtures of 80:20, 75:25 and 70:30 (under certain circumstances, smaller gradations are also advisable). The exact formulas can be found in Standowin iQ.

Then make the fine selection of the color shade (if necessary. Create variants or shades). Make sure that the spray patterns are clearly identified.

Important: Spray samples must be prepared using the same spraying and drying method
are carried out in the same way as the refinish!

Which mixing ratio gives how much gloss (E = gloss units)?

– 70:30> 25 E at 60 degree angle
– 75:25 OEM specification, for example MB 23 E at 60-degree angle Tolerance +/- 7 units
– 80:20< 15 E at 60-degree angle or. < 20 E at 85 degree angle

The formula for the correct mixing ratio can be found in Standowin iQ in the
Section "SPRAY MIXTURE" under products "SPEC MATT 2K SPECIAL.

Standox Special Matt must be thoroughly stirred immediately before use. The clearcoat/special matte mixture must also be carefully stirred before the hardener is added. Like other matting additives, Standox Special Matt can be used in all Standox clearcoats.

Since the clearcoats have different properties and mixing ratios, Standocryl VOC-HS Clearcoat K9520 from the Standox range is recommended for the repair. Only the VOC-HS clearcoat K9520 has the best basic properties for this special application area and is approved by the most important automobile manufacturers for repair work.

Paint process.

It is not possible to paint parts with matt clearcoat. Only complete components can be painted. Full coats should be applied by two refinishers, avoiding overlaps. Carry out all spraying and drying processes as for the selected spray pattern – even small changes can falsify the result. The more matt the clearcoat is set, the more accurate the preparatory work, basecoat application and clearcoat application must be

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2. Preparation and cleaning as usual.

Prepare for the complete matt-clearcoat application, because coats of the
Matt clearcoat with Smart Blend Plus is not possible.

3. Base coat and flash-off.

Paint the base coat as for a 2-coat paint job. Allow to flash off sufficiently afterwards.

4. Clear coat with matt clearcoat.

Apply the first spray coat and leave it for 5 to 10 minutes at 20 °C
intermediate flash-off. Then apply the second spray pass. Leave the component
Allow to flash off for 10 to 15 minutes before oven drying.

– Tip especially for the 80:20 mixture: The risk of spotting is reduced with a larger nozzle, for example SATA HVLP 1.5 mm at 2.0 bar inlet pressure.

– Tip for reducing streaking: slightly increase the painting distance to the object and narrow the webs accordingly. For large horizontal surfaces, e.g. an engine hood, apply the first and second coats at 90 degrees to each other, if possible. First and second pass make a classic cross pass.

5. Oven drying.

Allow the painted part to dry for 45 to 50 minutes at 60 to 65 °C object temperature.

Notes on paint care for matt finishes.

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There are many recommendations for the care of matt coatings, some of which are contradictory. Therefore, only Standox findings are described here – we cannot answer questions about third-party products.

Washing in a car wash is generally possible. However, do not select any care programs such as "gloss preservation" or similar. Preference should be given to systems that are gentle on the paint, because brush systems can have a polishing and thus gloss-increasing effect in the long term. The best and most gentle cleaning is hand washing with neutral soap, plenty of water and a soft sponge.

As with conventional gloss paints, it is best to remove bird droppings, dead insects and tree sap immediately. If this was not possible, soak the affected areas with water to remove the contaminants without mechanical aids if possible. Microfiber cloths are good for this. Tar stains can be removed from the car driver with silicone remover using the commercially available cleaners. Avoid strong rubbing with high pressure on the same spot.

Automobile manufacturers recommend not to apply stickers, foils or magnetic signs on series matte paints. Standox recommends the same for refinish coatings.

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