My brother has Maple Hardwood floors in his place, with a heavy coat
of clear poly-urathane to protect it. On this floor is a grand
piano. The Piano rests on three felt-bottomed coasters.

We recently moved the piano, and discovered that everywhere there was
coaster, the wood underneath was lighter than the surrounding wood.
(in a very clearly defined shapes). The floor itself is still
perfectly smooth and unmarred.

I was wondering if anyone had any ideas what caused the lightening (or
possibly the lack of darkening)? My first thought was it had
something to do with light, but the areas under the rugs which were
there the same amount of time, do not show the same lightening. Is
it possible that some chemical in the felt sept through the
polyurithane, and stained the wood???


John

julvr wrote:


We recently moved the piano, and discovered that everywhere there was
coaster, the wood underneath was lighter than the surrounding wood.
(in a very clearly defined shapes). The floor itself is still
perfectly smooth and unmarred.


Many unstained woods darken when exposed to sunlight. Many urethanes
"amber" with age and exposure to light.

If you leave the lighter area exposed to sunlight, it will probably
change to the color of the rest of the floor all by itself.

I'd allow the light to hit it and do nothing.

Barry

"julvr" wrote in message
news:54f4c$427640a8$455da0d2$8726@allthenewsgroups .com...


I was wondering if anyone had any ideas what caused the lightening (or
possibly the lack of darkening)? My first thought was it had
something to do with light, but the areas under the rugs which were
there the same amount of time, do not show the same lightening. Is
it possible that some chemical in the felt sept through the
polyurithane, and stained the wood???


The covered area of the floor stayed the original color. The rest of the
floor darkened from the light. With time and light, the spots will also
darken. I would let nature do its thing.

julvr wrote:
My brother has Maple Hardwood floors in his place, with a heavy coat
of clear poly-urathane to protect it. On this floor is a grand
piano. The Piano rests on three felt-bottomed coasters.

We recently moved the piano, and discovered that everywhere there was
coaster, the wood underneath was lighter than the surrounding wood.
(in a very clearly defined shapes). The floor itself is still
perfectly smooth and unmarred.

I was wondering if anyone had any ideas what caused the lightening
(or
possibly the lack of darkening)? My first thought was it had
something to do with light, but the areas under the rugs which were
there the same amount of time, do not show the same lightening. Is
it possible that some chemical in the felt sept through the
polyurithane, and stained the wood???



It would seem likely that the reast of the floor, or finish on it,
darkened over time, rather than the floor under the coasters
lightening.

Two things cause wood to darken over time, or in some cases (walnut)
lighten. One is exposure to light, the other exposure to oxygen.
It appears that you brother's floor demonstrates that it is exposure
to oxygen that causes maple to darken over time. The coasters no
doubt impede the diffusion of oxygen through the finish beneath them
far more than the rugs.

BTW, it is primarily oxygen that lightens black walnut. Left unfinished
it can turn almost amber in five years or so.


--

FF