Hi Steven,

I use Tried and True polymerized linseed oil which is supposed to have no
solvents or driers. I use a UV light booth to accelerate the drying and
find that the color change is what I would expect if I left the wood in
direct sunlight for a period of time.

Any thoughts on whether or not your experiments with UV inhibitors might
prevent the "normal" change I am seeing?

ps - glad to have you back!

George

"Steven D. Russell" wrote in message
...
Hello Owen,

No doubt dirty conditions in days long past contribute to the colour of
antiques, but the propensity of Linseed oil to darken is well known in
chemistry circles. I know of a few chemists who have spent years trying to
find a way to chemically reverse this problem with Linseed oil. No one has
ever been able to reverse the colour change without damaging the wood,
which
is obviously undesirable. Should you find a way, you would no doubt be a
very rich man.

Raw Linseed oil is the raw oil that has been packaged without any
additives.
Boiled Linseed Oils are similar, except the boiled version has been
altered
through the addition of chemical drying accelerators (solvents and
siccatives/driers) and may also include up to 15% Stand Oil, so the colour
change would be similar, if not more apparent in the boiled version.

Driers are oil soluble metal salts of organic acids. When these driers are
dissolved in aliphatic or aromatic hydrocarbons, they are know as
siccatives. When driers are added to drying oils, they are known as
"Boiled
Oils" Siccatives can also cause colour changes, depending on the specific
types used.

--
Better Woodturning and Finishing Through Chemistry...

Steven D. Russell
Eurowood Werks Woodturning Studio
The Woodlands, Texas

Machinery, Tool and Product Testing for the Woodworking and Woodturning
Industries

³Woodturning with Steven D. Russell² Volume #1 CD ROM * Available
Volume #2 CD ROM/DVD Video * Available Soon

On 8/18/04 9:48 PM, in article
, "Owen Lowe"
wrote:

In article ,
"Steven D. Russell" wrote:

One thing to consider when whipping up a batch of your own oil is that
Linseed Oil and Pure Gum Spirits of Turpentine will alter (darken) the
colour of your wood over time. Linseed oil has a habit of turning very
dark
to almost black over long periods of time... Go to any antique store
and you
will see this on old pieces finished with Linseed oil. Currently, there
is
no way to chemically reverse the colour degradation caused by Linseed
oil.

Are you sure this same result would occur with modern boil't linseed
oil?

I've heard the argument that the antiques that appear dark may be due to
the much dirtier heating systems of old - oil, coal and wood soot
becoming embedded in the finish. (I do know that raw linseed oil used
outdoors will often host mildew which will turn it very dark- but that's
a different situation.)