Antique Finish Restorer -- Linseed oil, turpentine, vinegar - DON'T
Posted: Tue Dec 15, 2020 4:13 pm
You occasionally see someone recommend this formula to spruce up an antique. Don't do this. The following is an excerpt from the Smithsonian
Donald C. Williams
Senior Furniture Conservator, Conservation Analytical Laboratory at the Smithsonian Institution
Drying oils, such as linseed, tung, or walnut oil, are a different matter
altogether. These materials solidify, or "dry" through a process of chemical
reaction with the air called oxidation. The drying process polymerizes the oil,
making it increasingly intractable with time and more difficult to remove with
cleaners or solvents. This is fine if oil is employed as the finish, but not good if
it is used as a polish. By itself, having a polish which is difficult to remove
would be irritating but not insurmountable. Unfortunately, this is not the
whole story. As drying oils age, they tend to become yellow or brown. Also,
drying oils are chromogenic (they become colored) in the presence of acids. In
this instance the oil adopts the dark, muddy brown/black opaque appearance
so prevalent in antique furniture. Traditionally, cleaning/polishing concoctions
were comprised of linseed oil, turpentine, beeswax, and vinegar (acetic acid).
This cleaning/polishing method, used widely even in the museum field until
recently, was and is a disaster waiting to happen. The results of this approach
are readily apparent to even the casual observer; a thick incrustation of
chocolate colored goo which is neither hard enough to be durable nor soft
enough to wipe off easily. Thus, due to the polymerization of the oil as it dries
and the reaction of the oil with acetic acid, the furniture is left with an
unsightly coating which is very difficult to remove without damaging the
surface of the object.
Donald C. Williams
Senior Furniture Conservator, Conservation Analytical Laboratory at the Smithsonian Institution
Drying oils, such as linseed, tung, or walnut oil, are a different matter
altogether. These materials solidify, or "dry" through a process of chemical
reaction with the air called oxidation. The drying process polymerizes the oil,
making it increasingly intractable with time and more difficult to remove with
cleaners or solvents. This is fine if oil is employed as the finish, but not good if
it is used as a polish. By itself, having a polish which is difficult to remove
would be irritating but not insurmountable. Unfortunately, this is not the
whole story. As drying oils age, they tend to become yellow or brown. Also,
drying oils are chromogenic (they become colored) in the presence of acids. In
this instance the oil adopts the dark, muddy brown/black opaque appearance
so prevalent in antique furniture. Traditionally, cleaning/polishing concoctions
were comprised of linseed oil, turpentine, beeswax, and vinegar (acetic acid).
This cleaning/polishing method, used widely even in the museum field until
recently, was and is a disaster waiting to happen. The results of this approach
are readily apparent to even the casual observer; a thick incrustation of
chocolate colored goo which is neither hard enough to be durable nor soft
enough to wipe off easily. Thus, due to the polymerization of the oil as it dries
and the reaction of the oil with acetic acid, the furniture is left with an
unsightly coating which is very difficult to remove without damaging the
surface of the object.