Blur not working with sprites (not writing in the zbuffer) ?

I am using the new Unity for creating a blur effect in a 2D game using only sprites. I tried to use the build-in Blur but it not working with sprites. I read that it because they are working with alpha blending which require each pixel behind each sprite to be saved (ZWriteOff) so that they are blended based on the alpha channel.

Another thing that I tried was making a duplicate of sprites-default.shader and within the shader replacing the lines: "RenderType"="Transparent" and ZWrite Off with "RenderType"="TransparentCutout" and ZWrite On. Unfortunately this also did not work, I red in some of the forums that the problem could be in the new Unity as this method work perfectly before.

Do you have any suggestions?