l'm soooo happy with the result this to be my first project in this feild ......
one thing confused me ..... why there is a black color in the plastic pipe inside the bottle ?? ...... l don't have any black color material ..... or in texture odes or somthing ...... anyone knows why this happed l'll be gratful to him
A couple things that come to mind are:
Your normals may be inverted: You can check this under the overlay options menu. Enable the face orientation option to see if there are any red faces. If so, select everything in edit mode and invert your normals: shift A > Shift N (you may need to tick the box in the redo panel). You want everything to be blue (in like 99.99% of circumstances).
It also might be caused by not enough lighting - or not enough light bounces. Your bottles have transparent qualities to them, as well as the pipes inside them so I'm guessing it may have something to do with the number of layers the light needs to pass through. I can't remember which video it was, but in the fundamentals of shaders and materials course JL discusses how light behaves when passing through transparent materials (ie glass) - it can appear black when it reaches certain angles based on the angle it is viewed from.
It could also be because of the thickness of the pipes? If they're relatively thick, try making them more thin.
I've just found the video where JL is talking about light paths and bounces - if you've got a spare 8 minutes, watch the whole thing. But pay attention when he starts talking about transparency and transmission bounces!
https://cgcookie.com/lessons/light-path-bounces
And if you're even more curious, watch the whole chapter, or even the whole course!
Try these things, but if they don't solve it let's wait and see if anyone else can jump in and help!
big love
the problem was with the thickness ..... l tried all no one worked except the thickness reduce