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I made this walnut table four years ago. About a year ago scratches or marks appeared, looks like they are under the poly finish. I tried buffing with mineral spirits, and recoating a section with poly. No change. Any ideas what caused this and what do I do now? They seem to be getting worse. The finish is min wax oil based poly.
 

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This is ONLY a suggestion...WAIT for the real knowledgeable people

I made this walnut table four years ago. About a year ago scratches or marks appeared, looks like they are under the poly finish. I tried buffing with mineral spirits, and recoating a section with poly. No change. Any ideas what caused this and what do I do now? They seem to be getting worse. The finish is min wax oil based poly.
Seems to be a whitish color under the topcoat.

I wonder if the old denatured alcohol trick would help here?

I have zero experience with this, just read it somewhere.
What you do is FIRST and MOST IMPORTANTLY... take the thing outside, far away from your house or any thing that could catch on fire. Dry grass, dry leaves, etc. Make sure and positively that you have a Fire Extinguisher or a garden hose ON and ready to put out a fire that may get out of control, check this first, twice.
NEVER do this inside any structure, house, home, garage, basement, shed, etc. OUTSIDE and away from anything. Fumes build up, a cat can knock over a can of alcohol, curtains can ignite, sawdust, etc...etc.
Fire is serious and very dangerous stuff.


Pour a light coat of denatured alcohol on the top and light it with a match. Let it go until the fire goes out by itself.
Try a small area first.
After the fire goes out wipe it with a soft dry lintfree rag in the direction of the grain, lightly.
If the white is gone, go for it and complete the job.

This is ONLY a suggestion, I expect the real knowledgeable people on here to yay or nay this before you try it.

I AM NOT AN EXPERT HERE... I AM A NOOB... REMEMBER THAT PLEASE.
Wait for others to respond for real opinions.

Also, it must be a fully cured surface to do this on, not a fresh one. THIS IS DANGEROUS, ONCE AGAIN, DO NOT DO THIS INSIDE A HOUSE< >YOU AND OTHERS COULD BE HURT or POSSIBLY DIE.

I assume no responsibility and neither does this website for your actions. Read this websites information and their disclaimer first, and very carefully.
YOU take all responsibility for what ever you do.
 

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That's not blush, setting it on fire won't help. The finish is actually lifting on the grain. For what ever reason the finish didn't bond well. If you can remember how it was finished and what products you used that might help to determine what happen. More than likely the stain wasn't allowed enough drying time before the finish was applied.

The white mark that Charles Neal suggested applying alcohol and setting it on fire was blush. It's where water has penetrated into the finish. Sometimes when you set something hot on a table moisture from the wood is drawn into the finish. I haven't tried the procedure yet myself but I will give it a try someday on a piece of furniture I'm going to refinish anyway. The man has a lot of experience with finishing so for now I will take his word for it that it works but until I try it I can't really recommend it.
 

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We have an introduction section where you can say a few words about yourself. If you fill out your profile in your "User Control Panel", you can list any hobbies, experience or other facts. You can also list your general geographical location which would be a help in answering some questions.

It looks to me like a variation in sanding marks from a coarser grit paper. I would use a methylene chloride stripper, like "Aircraft Stripper" in the blue quart can at HD, to strip off the finish. Then to sand uniformly the top with 180x (in the grain direction), with a block sander, and stain if necessary and apply finish.










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We have an introduction section where you can say a few words about yourself. If you fill out your profile in your "User Control Panel", you can list any hobbies, experience or other facts. You can also list your general geographical location which would be a help in answering some questions.

It looks to me like a variation in sanding marks from a coarser grit paper. I would use a methylene chloride stripper, like "Aircraft Stripper" in the blue quart can at HD, to strip off the finish. Then to sand uniformly the top with 180x (in the grain direction), with a block sander, and stain if necessary and apply finish.






.
I agree since that appears to be under the finish. It would also be nice to see under some ambient light without the flash.
 

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I agree with Steve and Cabinet man... The finish is beginning to let go .. Odds are your going to have to strip it and start over.. Cabinemans advice on the stripping is dead on.

I also agree the fire thing is not going to cure this, and everyone is correct , the fire thing is used to handle a blush, where moisture is trapped in the finish. I also agree to use extreme caution when doing it.

Oddly enough we had alot of questions about this technique , so we pulled the video of it and made it so you can see it . In the video we used a poly, but I have not found a finish it would not work on , I would go very easy if it were a shellac or french polish , as the alcohol could possibly distort the finish , in these cases I would use the Iron and oil .

The biggest danger here is to be sure you get the can and the cloth you apply with far enough away . In other words.. be careful... Use good common sense .. In the video however you will see its not as dramatic as it sounds .


Here is the video http://www.iplayerhd.com/playerframe/share/96f7b953-c343-4592-a586-9eabcc8bf375
 

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To me, those marks appear to be defects on the wood, not in the finish. They look like your tooling may be at fault. The face of vise jaws could be the culprit.The only way to deal with them is to strip the existing finishes re-sand carefully and then re-finish.

A trick to make sure you can see any defects before finishing is to wet a rag with mineral spirits and wet the surface of the wood. This will not only preview the color of the wood it you apply a clear finish but will also highlight and wood surface defects or sanding miscues.

The defects seem to be getting worse because yoo are focusing on them. There is no reason why they should really be getting worse.
 

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I am amazed every day on here.
You guys like Steve, Cabinetman and Neil... my hat is off to you all.

As far as my post, I posted it for myself as well as the OP. I crave knowledge in this trade and I want to learn as much as I can.
For a hobby only.
I didn't want to sound so dramatic regarding the fire potential, but I thought better safe than sorry. One never knows nowadays. The lawsuits going on in our country is an embarrassment.
Common sense no longer applies today.

Anyways, I learned something new from this and I'm grateful again.
Thanks guys.
 

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Discussion Starter #9
Thanks for the input. I am afraid stripping and refinishing is necessary. I am posting some more photos without flash.
 

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Thanks for the input. I am afraid stripping and refinishing is necessary. I am posting some more photos without flash.
Yes it will need to be refinished. Some substance has interfered with the adhesion of the finish. When I had a refinishing shop occasionally one of my guys wouldn't rinse the stripper off well enough when a table was stripped. The stripper contained wax to help it not evaporate so fast. Even though the wood looked fine when the table was sanded this wax was just smeared around and stayed there. Then when the finish was applied it didn't bond very well and soon started looking like your table. The only solution was to refinish it again. Fortunately in my case it was just a cheap refinish job done for a antique dealer just trying to get rid of some ugly tables. There was no hard fealings and I reworked anything he was unhappy with.
 
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