Hi! Help me please, when I testing to render a glass bottle(with custom glass shader) some artifacts apears. How can i solve this problem?

If your surface is NURBS or polygons being rendered as Subdivision Surfaces you may need to increase your Ray Shading Quality, either per-object (Object > Render tab > Dicing tab), or as a Mantra setting (Mantra ROP > Properties tab > Dicing tab).

Hope this helps.

Thx DaJuice! I turned down Dicing flatness parm in mantra advanced dicing tab, and it looks much better.