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Default Black spots

I have some old varnished wood I want to strip down and reuse. This wood
has black areas around the old screw holes. How do I get rid of the black
w/o sanding away all the wood?
Thanks
Gordon


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Default Black spots

Gordon inscribed in red ink for all to know:
I have some old varnished wood I want to strip down and reuse. This wood
has black areas around the old screw holes. How do I get rid of the black
w/o sanding away all the wood?
Thanks
Gordon


oxalic acid should take care of them...

bob
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Default Black spots

Somewhere, someplace there must be someone that has had good luck getting
rid of dark areas in poorly maintained brightwork using oxalic acid. It has
never worked for me.....sometimes the black is a little lighter but not much
better.
Dave
"RW Salnick" wrote in message
...
Gordon inscribed in red ink for all to know:
I have some old varnished wood I want to strip down and reuse. This
wood
has black areas around the old screw holes. How do I get rid of the black
w/o sanding away all the wood?
Thanks
Gordon


oxalic acid should take care of them...

bob



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Default Black spots

I tried it yesterday. Heavy on the oxalic in hot water. Used paper towels
wetted down and left on the spots for an hour. Yup, black is still there!
Gordon
"Dave W" wrote in message
...
Somewhere, someplace there must be someone that has had good luck getting
rid of dark areas in poorly maintained brightwork using oxalic acid. It

has
never worked for me.....sometimes the black is a little lighter but not

much
better.
Dave
"RW Salnick" wrote in message
...
Gordon inscribed in red ink for all to know:
I have some old varnished wood I want to strip down and reuse. This
wood
has black areas around the old screw holes. How do I get rid of the

black
w/o sanding away all the wood?
Thanks
Gordon


oxalic acid should take care of them...

bob





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Default Black spots

Is this wood oak, by any chance? If so, the discoloration may not be due
to fungus/mold/mildew, but rather due to a chemical reaction between the
tannic acid in the wood and the metal in the screws. When done
intentionally, it's a technique known as "ebonizing".

Regardless of the cause, one solution would be to drill the holes
oversize and glue in plugs to fill the holes. Done properly, it could
create an interesting detail when the wood is reused.

Gordon wrote:
I tried it yesterday. Heavy on the oxalic in hot water. Used paper towels
wetted down and left on the spots for an hour. Yup, black is still there!
Gordon
"Dave W" wrote in message
...
Somewhere, someplace there must be someone that has had good luck getting
rid of dark areas in poorly maintained brightwork using oxalic acid. It

has
never worked for me.....sometimes the black is a little lighter but not

much
better.
Dave
"RW Salnick" wrote in message
...
Gordon inscribed in red ink for all to know:
I have some old varnished wood I want to strip down and reuse. This
wood
has black areas around the old screw holes. How do I get rid of the

black
w/o sanding away all the wood?
Thanks
Gordon


oxalic acid should take care of them...

bob






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Default Black spots

Gordon inscribed in red ink for all to know:
I tried it yesterday. Heavy on the oxalic in hot water. Used paper towels
wetted down and left on the spots for an hour. Yup, black is still there!
Gordon
"Dave W" wrote in message
...

Somewhere, someplace there must be someone that has had good luck getting
rid of dark areas in poorly maintained brightwork using oxalic acid. It


has

never worked for me.....sometimes the black is a little lighter but not


much

better.
Dave
"RW Salnick" wrote in message
...

Gordon inscribed in red ink for all to know:

I have some old varnished wood I want to strip down and reuse. This
wood
has black areas around the old screw holes. How do I get rid of the


black

w/o sanding away all the wood?
Thanks
Gordon



oxalic acid should take care of them...

bob






Hi Gordon -

I assumed that the black stain was iron - either leached from iron/steel
fasteners, or from the action of iron-fixing bacteria. Oxalic acid is
quite specific for iron stains.

But black stains could come from other things too. Almost all metal
powders look black. Metal powder could come from continued action of a
fastener working in a hole, wearing away a fine dust of fastener and
embedding it in the wood (eg. check your rag after using brasso...). I
do not know how to remove this dust (and the method would depend on the
particular metal involved) without damaging the wood.

Also, the black could be due to bacteria colonizing the wood where it
was unprotected by varnish, and had access to moisture. In this case,
regular cholrine bleach will do a good job.

bob
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Default Black spots


Brian Nystrom wrote:
Is this wood oak, by any chance? If so, the discoloration may not be due
to fungus/mold/mildew, but rather due to a chemical reaction between the
tannic acid in the wood and the metal in the screws. When done
intentionally, it's a technique known as "ebonizing".


If that's the case, bleach will work. Sam

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Default Black spots

On Thu, 05 Oct 2006 18:16:41 GMT, Brian Nystrom briar.
Dave
"RW Salnick" wrote in message
...
Gordon inscribed in red ink for all to know:
I have some old varnished wood I want to strip down and reuse. This
wood
has black areas around the old screw holes. How do I get rid of the

black
w/o sanding away all the wood?
Thanks
Gordon


Sometimes hydrogen peroxide will lighten dark spots. A trick I learnes
from an antique dealer.

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Default Black spots

On Wed, 4 Oct 2006 09:17:09 -0700, "Gordon"
wrote:

I have some old varnished wood I want to strip down and reuse. This wood
has black areas around the old screw holes. How do I get rid of the black
w/o sanding away all the wood?
Thanks
Gordon


Life is often a matter of compromise. You have to sand quite a bit
anyway if you are refinishing wood that's really on it's last legs. I
strip with Citristrip, power sand with coarse grit down to the pink,
then smooth and give two doses of Daly's AB, sometimes spot dosing the
dark spots again. Then it's a light sand and start varnishing.
I tried staining on a piece with embedded rust/rot/whatever from
around bronze screws which had broken off but it didn't come out as
well as I had hoped even though the holes were no longer noticeable.
It all takes a long time and needs fairly high, consistent
temperatures. The good news is it's worth it.
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