Furniture Finishing, Refinishing, & Restoration

Q&A Forum - Removing black water stains on oak table top - help!

anne1 - Wed Feb 22, 2006 10:27 am
Post subject: Removing black water stains on oak table top - help!
I have an antique oak table top with several large black water rings left from flower pots leaking on it. The stains have been there for years now. Is bleaching the right way to try and get rid of them and if so, how to best apply and do if for sure? Thank you for any help on this.
Bob Boardman - Fri Feb 24, 2006 8:39 am
Post subject:
Anne

Bleaching is the right way to do this. Black stains mean that water has gotten into the wood, not just the finish.

To start, you have to remove ALL the finish from the top (not just the damaged area. This usually means using a stripper. Once done with the stripper, wipe the top down with a rag dampened with paint thinner, then wipe with dry towels.

Use gloves and eye protection when bleaching. I usually start by wiping the entire surface, liberally, with regular laundry bleach. Then leave the table for 24 hours. At that point the stains are usually gone, or a barely visible. If barely visible, wipe down again, and let dry. When the piece is dry, I wash the surface 2 - 3 times with wet rags, dryin in between, and using new ras each time. Then let the table alone for 2 days, so it completely dries.

At this point you'll have a "blank canvas"...you can stain/color it however you want. One thing you can do is to very lightly sand the surface with a 400 grit paper, diagonally to the grain; first diagonally to the left, then diagonally to the right. Use a light touch. The purpose is to remove all the raised "hairs" that are left over from the water and bleach. Vacuum up the dust and you're ready to go.
anne1 - Fri Feb 24, 2006 10:00 am
Post subject:
Thank you for the detailed info. It is much appreciated! Just one question? Do I put the bleach on full strength or not? I would have thought to try and just bleach on the ring area - glad to know to do the whole surface.
Bob Boardman - Sat Feb 25, 2006 12:20 pm
Post subject:
Anne

Apply full strength. If you apply only to damaged area, you'll have to blend in color afterwards...that takes a bit more skill and work, and doesn't usually produce as good a result.

Here's some pics from an upcoming article I'm working on. (This maybe too much for a single post, so I'll carry over onto next post.)
Bob Boardman - Sat Feb 25, 2006 12:32 pm
Post subject:
Here's the rest of the pics and process
anne1 - Sat Feb 25, 2006 5:02 pm
Post subject:
Thank you for the great pictures and detailed info. on removing the black water stain! I am ready to work on my table in the garage - as soon as warmer weather permits this spring.
Bob Boardman - Sat Feb 25, 2006 5:05 pm
Post subject:
Anne

Glad to help...let us know how you make out
ellenball - Tue Mar 14, 2006 7:08 pm
Post subject: black water stain

hi.... the picture directions for removing the ugly black water stain is just what i needed. one question however. my damaged furniture is a buffet that was redone about 4 years ago when it was stained with minwax stain with polyurethene. do i need to strip the top of my buffet or will sanding do the trick? thanks
flyfisher - Wed Mar 15, 2006 9:26 am
Post subject: Great article, water stain on mahogany question
Wow this is a great article... And this topic is
very timely to me as I was just going to post
a topic question on the same subject. My water
stain is on a mahogany desk. I believe the top
is a plywood mahogany veneer. Do you think
this process would be the same? I'll try to post
a pic tonight...
flyfisher - Wed Mar 15, 2006 11:10 pm
Post subject: Here are some pics
Here are some pics of water damage, is this repairable?
Bob Boardman - Thu Mar 16, 2006 12:43 pm
Post subject:
For Ellen:

Yes, unfortunately you have to remove the finish. Since the piece has a poly finish, you're best bet would be to use a stripper with methylene chloride in it. Wear gloves/goggles, and after applyin the 1st coat of stripper, wrap plastic wrap tightly over the surface, and leave alone for about 4 - 6 hours. The plastic keeps the stripper solvents from evaporating as quickly, causin them to work more on the finish. After 4 - 6 hours, remove the plastic (it often disintegrates, but don't worry about that) and see if you can remove the finish. If so, go to it. If not repeat the stripper - plastic wrap step. Poly is a hard durable finish, so it takes a bit of time for the stripper to work. Once done, wipe the surface with a ra dipped in paint thinner or naphtha, and proceed as above. Good Luck.

To FlyFisher:

Good photo...it shows 3 types of damage: superficial finish damage, severe finish damage, and wood stain damage.

As with Ellen above, you need to remove the finish. I'd strip the surface, versus sanding, even though this piece probably has a lacquer finish (Sanding a veneer can cause it's own set of problems). You won't have to use the plastic wrap, and could begin removing finish after about 45 mins - 1 hour. After that proceed as above.
flyfisher - Thu Mar 16, 2006 1:09 pm
Post subject: Thanks Bob
Thanks Bob,

As you may have seen elsewhere on the forum I have
another project, so I may alternate between the two
starting this weekend. Just for knowledge's sake can
you tell me how you can determine the finish type?

Thanks,

Eric
Bob Boardman - Fri Mar 17, 2006 4:39 pm
Post subject:
Eric

Using a cotton swap or small cloth:

a) dip in denatured alcohol and rub on a small, inconspicuous spot. If swab/cloth has finish on it, or if finish on the piece gets sticky, it's a shellac finish

b) dip in lacquer thinner and rub on a different small, inconspicuous spot. If swab/cloth has finish on it, or if finish on the piece gets sticky, it's a lacquer finish.

If it's not a lacquer or shellac finish, then it's probably a polyurethane, oil, combo of the 2 (varnish), or commercial finish.
flyfisher - Fri Mar 17, 2006 6:13 pm
Post subject:
Thanks again Bob
ellenball - Sat Mar 18, 2006 5:10 pm
Post subject: thanks very much!!!


thank you so much for the great advice. i will follow your directions step by step and i'm sure my buffet will again get the pleasant compliments it is used to! finding this website has been so informative and interesting. your expertiese and generousity in responding are appreciated!!
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