Dark Spots After Sanding

[dasaes0514]

Hi all,
I'm new to woodworking and am taking on a dining room table refinishing project. the table had a dark top and we wanted to make it much lighter so I tried taking off the 1st layer with a belt sander using 120 grit then 120 again with palm sander, then 150, then 220. There are some spots left from the belt sander that feel like the sander went too deep, for lack of better terms, and now I have several black marks. I sanded with the grain, in one direction, and kept the sander moving. Any ideas what caused this and how do I fix it so I can apply really light stain? I was told the wood looked like poplar if that helps any and it's solid wood and not veneer or pressboard.

 

[Roy G]

Dave, have you tried bleaching the spots? Try a little bleach at an edge and see if the stain gets lighter.

Roy G

 

[farmerbw]

Dave, I don't have an answer regarding the cause of the staining, unless it's something from one of the sanders itself. The only suggestions would be more sanding or maybe trying a card scraper. You can see what appears to be unevenness, chatter maybe?, in the wood from the belt sander though. How wide is the top? You might be able to enlist the help of a member with a wide belt sander and get it sanded to a more even consistency and hopefully remove the staining in the process.

I'm not sure that's Poplar though, it looks more like Rubber, or Para, wood to me. I've sanded some of it in the past and don't recall if I experienced any staining like that, or at least to that extent.

B

 

[dasaes0514]

Dave, I don't have an answer regarding the cause of the staining, unless it's something from one of the sanders itself. The only suggestions would be more sanding or maybe trying a card scraper. You can see what appears to be unevenness, chatter maybe?, in the wood from the belt sander though. How wide is the top? You might be able to enlist the help of a member with a wide belt sander and get it sanded to a more even consistency and hopefully remove the staining in the process.

I'm not sure that's Poplar though, it looks more like Rubber, or Para, wood to me. I've sanded some of it in the past and don't recall if I experienced any staining like that, or at least to that extent.

B

From one of the other forums I posted too I'm hearing that this may be a vaneer top and I sanded through it but then the vaneer would have to be very thin because I didn't put any pressure on the sander and kept it moving in one direction the entire time.

 

[Jeff]

Where did you get this dining table and what did it look like before you started belt sanding?

I was told the wood looked like poplar if that helps any and it's solid wood and not veneer or pressboard.

Who told you that poplar hogwash? I agree with Brian on "rubber wood" and it probably wasn't veneered either so you didn't sand through it either.

http://www.wood-database.com/rubberwood/

http://www.hobbithouseinc.com/personal/woodpics/rubberwood.htm

The stain looks like mold/mildew so start with some grocery store Chlorox diluted in water (1:3) and brushed over the entire surface including the black areas. Stand the top vertically so that it's easy to rinse the excess bleach off. Repeat if necessary and let it dry throughly for several days.

Pics then?

 

[Bill Clemmons]

I agree w/ Jeff. Definitely not Poplar. What I call the mystery wood from Southeast Asia, probably in the rubber family. You see a lot of it in imported furniture.

The stains (dark spots) are not burns from sanding. Look closely and you can see something has penetrated into the grain. Mold/mildew, as Jeff said, is a likely option. Another is something dark was spilled on the table and penetrated the topcoat, into the wood. Another possibility is something got in the tree when it was growing. You see that sometimes w/ wood. You said the top was a dark color. At the factory they probably saw that "defect" and decided to stain it dark rather than trying to get the spots out. If that's the case, you're stuck w/ it. But try Jeff's bleach solution first. Hopefully that will work,

 

[dasaes0514]

Will try the bleach and see what happens, thanks for the feedback!
From some follow up research I'm thinking it's a veneer top that I sanded through to the darker wood which is what the "stain" actually is. I flipped the table over and the "stain" is very similar to the dark wood so that seems to make sense. We got the table off of Craigslist as a project piece with a dark stain from the factory. I think we can salvage it with a little darker stain than we originally wanted and give it a distressed look.

 

[ncfromnc]

THe dark spots look very much like ebonizing. In other words....maybe an iron or steel pan was left on the table and got wet. This happens on oak tables a lot. The ebonizing may be shallow or deep. We usually use the old vinigar and steelwool thing to get the ebonizing effect. It is iron reacting with tanons in the wood.

 

[MikeZ]

Can you take a better above or "Bird's Eye View" of this spot?

 

[Mike Davis]

I doubt that is veneer due to the patched/glued up short pieces. More likely solid wood. The wood is stained possibly while in the tree or during warehouse waiting for processing. Bleach may work but household bleach is very weak, won't do much. There is commercial wood bleach in a two part system that would do much better. Then you can stain is you want or just finish.

The reason it was stained dark was to help hide the cheap wood- short pieced together look and to make it look "richer".

For your next project try to be more selective about the wood, the construction, and the finish. Dark stain always hides a multitude of sins. Paint is even worse.