Can hand grease cause any trouble by applying finish? Or should I clean (degrease) all the wraps before finishing? Which degreasing agent you would recommend?
Thanks in advance.

The best thing you can do is to avoid touching the threads anymore than is absolutely necessary. Washing your hands and even wiping your fingers with isopropyl alcohol before wrapping is a good idea.

As far as how to "de-grease" the threads if you feel you have contaminated them with an unusual amount of hand oils is something I will leave to someone better versed in that arena than myself.

Normally I use color preserver on all my wraps and believe that tends to seal in any such oils, if they exist.

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On hand oils if there is alot on threads then the only thing that can be done is to rewrap them as when you put the coating on the threads,the coating will pull away from the area were you touched it.
Neal Cissel

One preventative measure is using a guitar pick to do all your straightening and packing. This keeps your hands off. The ONLY time my hands come in contact with the threads is starting the wrap and slightly when tying off. I also keep my fingers cleaned with denatured alcohol every 30 minutes or so.

The handiest thing I've done is to keep spray bottles of alcohol at all my 'stations' (wrapping,shaping, & glueing).This keeps the alcohol handy,and,I'm able to get it with one hand.Very easy to 'clean-up' glue -smeared blanks during handle assembly.

During wrapping of a buttwrap,I clean my hands every pass or two just to kill any oils or sweat,sneezes,coughs,etc...."G"

I all way wash my hands before and dureing my wrappiing . It is also a good idea to wash your rod down with a light dish soap and rinse & dry throughly before wraping. The reason for washing rod is how knows how many people have touched the rod.
Good Luck Bob

Don,t you have to touch the wraps to adjust the guides before finishing?

Unless you are an extremely heavy sweater, you should not encounter any problems. Just wash your hands before you sit down to work and if you feel that your hands are feeling oily, wash again. Otherwise, you should not have any problems.