It all depends on the section thickness. If the softer paraffin is set to section thin it will ribbon better than if it is set to section thick, where ribbons will be more difficult to form.
A hard (high melting point) paraffin will always produce better ribbons at any thickness since it holds the tissue better (when cooled).
The ribbon formation has also to do with the speed you section, a constant, low speed, rhythmical, produces better ribbons (with any type of paraffin), than sectioning with speed "bursts". That constant low speed motion permits the sections to get in contact better and assures the ribbon better. For rotary microtomes it is all in the wrist!
The sliding microtome requires more force, although you can control better the blade movement (over the static specimen) that is an inverse situation with the rotary (where the specimen is moving against a fixed blade). These two opposite configurations, from the mechanical point of view, also influence the ribbon formation.
So there is always a trade off between instruments and techniques.
Finally, I have never noticed any "mess in your brain".
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