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No-Scratches are expected on the surface of ND-coated filters for making a film. Even a teeny tiny scratch in particular on the darker densities vividly affects your image on the screen. That being the case, we need a proven scratch-resistant coating.
A general testing method to measure the hardness on the surface of the coating is called the "Pencil Hardness Test" which also prevailed in testing screen protection.
In the marumi brand product lineup, DHG Super Series is the hardest, equivalent to the maximum 9H protection in the Pencil Hardness Test.
WSND-ES exceeds the maximum 9H hardness and needs to be measured how hard the coating strength would be.
Yasuda seiki_553-S; PENCIL SCRATCH HARDNESS TESTER (HAND PUSH)
corresponding to ISO/DIN15184 and JIS K5600-5-4
We set our original standard of inspection method to check how much load WSND-ES can bear compared to the market competitors in the filming industry.
The original standard of inspection method;
- uses the same jig as JIS K5600-5-4, corresponding to ISO/DIN 15184
- replaces the 9H pencil with two types of metal pins "A" or "B" that are close to the hardness of plate glass around 52 HRC (Rockwell hardness).
‐ the metal pin "A" (hardness 48 to 52 HRC), a lighter hardness is initially used gradually increasing the load until the glass is scratched.
- in case there is no scratch observed, the same test performs replacing with the metal pin "B" (hardness 58-60 HRC)
- The conditions of scratches are checked visually.
The pictures below shows an enlarged microscope focus of each glass surface.
*Under the condition of load 500g with metal pin "B" (hardness 58-60 HRC)
*Under the condition of load 850g with metal pin "B" (hardness 58-60 HRC)
While there is no trace of scratches on the surface of WSND-ES 2.4 up to theload 850g with metal in hardness 58-60HRC, the other NDs shows an obvious trace of scratches visible.
In conclusion, WSND-ES proves the excellent enhanced scratch resistance to be able to survive in a harsh filming environment.
Please be cautious and keep in mind that this test does not guarantee intentional damage on the surface of glasses.
Thank you for your attention, and enjoy your cinematography life!
Marumi team
