Hey mirek03, you was right ! The blobby surface has the visible in refraction and reflection turned off for default. It works fine. I did not try the other answers, but Thanks for everybody. Now i would like the particles to appear but not be refracted into the surface. Is it possible ?! The scene is a coke pouring and the particles will be the bubbles. I used real flow with a script that change the liquid to foam when it collides. Exported the liquid as mesh and bubbles as particles. Now i'm trying to render this. The liquid i used dielectric material and for the bubbles i will use the blobby surface. Thanks