Let me clear up a few points about alcohol.  First, shellac thinner
is 95% ethyl alcohol (also called ethanol) and 5% water.  This ratio
is chosen because ethanol and water form a binary azeotrope at this
ratio with a boiling point of 78.15 degrees C. [Celsius].  Pure (100%)
ethanol has a boiling point of 78.3 degrees C.  Water has a boiling
point of 100 degrees C.  This is counterintuitive but true.

Historically, ethanol was made by fermentation of a water-based
solution of sugar and/or starch.  The distillate of this mixture, with
composition of 95% ethanol and 5% water, represents the mixture with
the lowest boiling point.  It is never possible to concentrate ethanol
by distillation from water with a composition any higher than 95%
ethanol.

Additionally, if one were to place a drop of 95% ethanol & 5% water
on a mirror and watch it evaporate, it would evaporate -- completely --
leaving nothing behind.  This is a principle reason why this 95:5
mixture is used for cleaning optics and anything else on which a
residue is undesirable.

Ethanol is seldom produced commercially (except for booze) by
distillation.  The usual commercial preparation calls for reacting
ethane (gas) with superheated water (steam) to form (you guessed it!)
100% ethanol.  100% ethanol is available for purchase, but since it
is deliquescent -- meaning that it absorbs water from the atmosphere --
it soon becomes the azeotropic composition of 95:5.  Thus most
commercial ethanol is intentionally diluted with water to the 95:5
concentration because it represents the composition with the lowest
boiling point and hence the most stable composition for use in a normal
atmospheric environment.

Since some folks have been known to drink beverages containing ethanol,
and since governments like to tax this brew, commercial alcohol is
generally "denatured".  This simply means that something is added that
will make you sick if you drink it.  These additions are chosen so that
they do not interfere with industrial uses like cleaning or solvency.

Isopropyl alcohol is more common and cheaper than ethyl alcohol.  It
works equally well as a degreaser and is less likely to damage delicate
surfaces.  It also forms an azeotropic mixture with water.  It also
leaves no residue.

All this being said, if I had to clean "grease" from old wood parts,
I would use trichloroethylene [TCE or "trichlor"].  It dissolves
grease readily without harming the wood.  It is not flammable.

Commercial wood degreasing is done with methylene chloride in special
sealed vessels.  Stay away from methylene chloride unless you know what
you're doing.  Trichloroethylene works as well but not as quickly
(we're talking seconds here) and it is safe to use, but try not to
breathe the vapors for long.

If you do use alcohol, be aware that it ignites easily and that the
flame is nearly invisible.

I could go on but you're probably asleep by now.

Bill Finch