Are the fusel oils visible?

[Still_Crazy]

I have noticed while watching the drip that sometimes there will be a
chemical 'wave' or syrup appearance from the drip when it enters the collection
container. I assumed that it might be some fusel oils from running a little
high on the temp or too long into the tails?

Also, after being in the freezer for several hours I'd let a bottle heat back up and
wipe it dry on the outside. Again, sight across the surface and with the first bump
or light shake of the bottle I can see some of the wave or syrup action at the surface.
Again I assume that this is fusel oils that could should of been avoided to begin with?
If they always float to the surface then a guy should be able to siphon that top layer leaving
yet a cleaner product?

My searches here still take a while so pardon me if I have missed this ? or topic in the past.