Matt finishes for the Automotive industry are notoriously difficult to matt off. This is due to the solid content of the coating along with the isocyanate hardener used to cure the Coatings.
Why is it hard to get a good clear matt finish?
Unfortunately the Automotive industry uses a lot of chemicals and ingredients from the industrial side. Matt finishes being one of them. Matt finishes use a product called silica. This powder is what matts off the surface. This works by all the tiny silica particles become exposed to the top of the coating when the solvent evaporates and the film shrinks back.
To get a good matt finish special grades of silicas are required along with special additives to help give a good matt finish.
What gloss levels determine what category the matt finish falls in?
We measure the gloss in GU or Gloss units. Every Manufacture may have their own interpretaion of what their percentages are.
Matt or dead matt is below 5%
A standard matt is below 10%
Satin ranges from 20/35%
Gloss is from 80% onwards.
In short below 10% is matt and 20/35% is satin. Satin can be as high as 45%
Now we understand the gloss levels we need to understand the importance of application.
Applying matt finishes can be difficult. Matt finishes always look best when applied at thinner film builds especially dead matt. So adding thinner to the matt coating should make the finish more matt.
The application does make a massive difference!
Apply 3 coats of matt clear in one go and the matt will turn glossy. Not enough coats than your finish will be too matt. It's hard to match a matt finish without doing a sprayout first. We reccomend doing some spray out test panels on our Colour Examination Cards to make sure you are happy with the finish first.
Do Environmental conditions affect matt finishes?
Yes! Matt coatings can be influenced by the environment that the coating is being sprayed in. Humidity can prevent the coating from becoming as matt as it could. We reccomend spraying in a clean, dry environment such as a spray booth as this will ensure the best finish possible.
What spray gun is best to spray matt finishes?
Generally a good quality spray gun with a 1.2 setup would be best. Matt clearcoat does not need to be overloaded as the finish cannot be flat and polished like normal clearcoat.
Can i flat and polish a matt car?
Unfortunately matt vehicles cannot be polished. polishing matt vehicles with remove the matt finish and turn it shiny. When shiny that finish will have to be re-matt clearcoated to get the matt finish back again.
Why do mixing ratios change the matt finish?
Isocyanate in the hardeners affect the matt finish drastically. This is why 2K coatings are hard to matt off. Generally the less isocyanate the more easily a matt coating can be achieved.
This is why our Matt Clearcoat has different mixing ratios depending on what finish is needed.
3:1 with MS hardener and 4:1 with HS hardener along with 20% thinner gives the same matt finish as the 4:1 ratio uses less hardener giving the same finish as the MS hardener.
For satin all we have to do is up the hardener levels.
2:1 with MS hardener or 3:1 with HS hardener gives a nice satin finish with a nice smooth surface.
Make sure that all matt coatings are mixed thouroughly before using as over time the matting ingredients may drop out to the bottom of the tin. This is normal and usually a quick mix will allow the contents to be mixed in easily enough.