Kato Unitrack and sunlight/UV

[peteski]

How is the multi-colored simulated ballast effect created?

From what I can tell they mix the black and white flakes (same consistency like glitter) into the liquified semi-translucent gray plastic and inject that mixture into the mold.. Then they paint the ties and lastly, insert and crimp the rails.  Those flakes are made of a material which has much higher melting temperature than the plastic, so they do not dissolve in it.

[MK]

I was going to guess the same as what Peteski said.  Think solid surface kitchen counter top material Corian (by Dupont).  With Corian, the more "stuff" they mix in, the more expensive it is!

[Point353]

From what I can tell they mix the black and white flakes (same consistency like glitter) into the liquified semi-translucent gray plastic and inject that mixture into the mold.. Then they paint the ties and lastly, insert and crimp the rails.  Those flakes are made of a material which has much higher melting temperature than the plastic, so they do not dissolve in it.

If the "ballast" flakes are mixed into the gray plastic, how is it that they only appear on the top side of the track pieces?
The bottom is a solid gray color, without any texture.

[peteski]

If the "ballast" flakes are mixed into the gray plastic, how is it that they only appear on the top side of the track pieces?
The bottom is a solid gray color, without any texture.

The texture (ballast shaped bumps) are created by the mold.  The colored specks are just for visual effect. They also show up on the bottom. and if you were to cut the roadbed and look in the cross-section you would find those white and black bits in it.