LumberJocks

Grey Blotches in Refinished Cherry

  • Advertise with us

« back to Finishing forum

Forum topic by Casual1 posted 06-27-2020 07:33 PM 536 views 0 times favorited 26 replies Add to Favorites Watch
View Casual1's profile

Casual1

8 posts in 9 days


06-27-2020 07:33 PM

Topic tags/keywords: cherry blotch table 600gl splotch

Hi all!

I’m refinishing this cherry table.

I’ve done the following:

1. Stripped the old polyurethane finish using Blue Bear 600GL in two passes, scraping between.
2. Rubbed 600GL into the wood, by hand, using 0000 steel wool.
3. Cleaned the wood using TCP in water and 0000 steel wool.
4. Cleaned again using clear water and a sponge and rag.
5. Cleaned again using lacquer thinner and paper towels.
5. Thoroughly dried the wood.
6. Sanded, starting at 150, now down to 60, using both an orbital palm sander and a flat board.

Problem:

I have these grey spots that appear to be residual finish, or might be steel wool. I’ve sanded the beejezus out of this thing and don’t seem to be altering them in any way. Could they be wood? Or do I have to keep sanding until they’re gone. Maybe a power-plane? Belt sander?







The future plan is:

1. Sand to 220. Board it flat.
2. Apply Charles Neil Pre-color Conditioner.
3. Sand lightly w/ 320.
4. Spray 6 coats General Finishes Enduro Conversion Varnish (Satin). (This table gets HEAVY use.)

Thanks for any help you can offer!

-- Guy, San Diego


26 replies so far

View Kazooman's profile

Kazooman

1489 posts in 2723 days


#1 posted 06-27-2020 08:40 PM

You may be right about the steel wool being the culprit. Cherry has quite a lot of tannins and the use of steel wool with the water might have resulted in stains. FYI, a commonly used technique in woodworking is “ebonizing”. You soak some steel wool in vinegar for a day or two and then wipe the liquid on the wood. Gives a nice black color.

If the stains are from the water and steel wool they likely go pretty deep into the wood. You might not be able to sand them out. You indicated that the table gets very heavy use, so it is also possible that the grey blotches arose from that.

Either way, you could try treating with oxalic acid solution. Be VERY careful and do a test on some hidden part of the piece before going after the entire table top. You can Google about oxalic acid in woodworking and get a million hits. Here is a starter:

https://www.popularwoodworking.com/article/oxalic-acid-a-very-useful-bleach/

Good luck and welcome to LumberJocks.

PS: You can also Google ebonizing wood and learn about that.

View Robert's profile (online now)

Robert

3739 posts in 2252 days


#2 posted 06-27-2020 10:20 PM

No it’s simply variation in color, common with cherry.

You’ll have to stain the light strips to match. Use the underside to figure it out,

Before you do any staining seal it with dewaxed shellac. Tape off lighter strips to selectively stain. You can also use toner to dial in the color.

Before you do anything you might try treating the whole top with a dye stain.

-- Everything is a prototype thats why its one of a kind!!

View Casual1's profile

Casual1

8 posts in 9 days


#3 posted 06-27-2020 11:55 PM

Thank you both. I read up on bleaching and will have to do extensive testing as my problem color is grey, and I’m worried I’ll just bring everything up a notch in tonality, but the color variation will still be there. (grey vs pink / yellow) I’ll also check out ebonizing as I didn’t see any cautions about using steel wool. Certainly my TCP water never went to grey / black, more of a rich brown that I wouldn’t think would result in the grey spots. And I didn’t see any evidence of coloration when I used the wool with the 600GL.

But thanks for the help! I’ll definitely post pictures when it’s done. (Thought it’s not much to speak about. The canoe restoration will be more interesting, though there’s not a lot of wood on that.)

-- Guy, San Diego

View Kazooman's profile

Kazooman

1489 posts in 2723 days


#4 posted 06-28-2020 01:13 AM


No it’s simply variation in color, common with cherry.

You’ll have to stain the light strips to match. Use the underside to figure it out,

Before you do any staining seal it with dewaxed shellac. Tape off lighter strips to selectively stain. You can also use toner to dial in the color.

Before you do anything you might try treating the whole top with a dye stain.

- Robert

Just a quick question. Are you saying that the OP had all of these grey stains in the finish of his table for all these years as a natural variation in Cherry and never even noticed it? I don’t think so, I think the problems showed up during, and as a direct result of, his finish stripping protocol. You suggest that now that he is going to refinish the table top he should reach out for a fix for his year’s long problem that he never even knew he had? Why would he want to treat the whole top with a dye stain? I think he is trying to preserve the natural cherry color. He wants to remove the grey stains that occurred (not showed up) during his finish stripping process. He does not want to stain (nor paint) the table.

View pintodeluxe's profile

pintodeluxe

6150 posts in 3584 days


#5 posted 06-28-2020 03:39 AM

1+ the grey is the wood itself, not the finish.

Learn to love it, or pick a finishing schedule that obscures it.

BTW cherry is one of the most difficult species to finish. Master that, and you can do anything.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View mel52's profile

mel52

1445 posts in 1036 days


#6 posted 06-28-2020 05:36 AM

If you think it’s something you might be able to get out, try using a card scraper. Mel

-- MEL, Kansas

View Casual1's profile

Casual1

8 posts in 9 days


#7 posted 06-29-2020 07:16 PM


BTW cherry is one of the most difficult species to finish. Master that, and you can do anything.

- pintodeluxe

Well that’s a bit terrifying. Fortunately I’m going for “natural”, so I guess I get what I get, as far as color, though I will try to make the texture perfect.

Thanks again!

-- Guy, San Diego

View typing's profile

typing

7 posts in 356 days


#8 posted 06-30-2020 10:52 PM


1. Sand to 220. Board it flat.
2. Apply Charles Neil Pre-color Conditioner.
3. Sand lightly w/ 320.
4. Spray 6 coats General Finishes Enduro Conversion Varnish (Satin). (This table gets HEAVY use.)
- Casual1

Why do you need precolor conditioner if you are not staining ?

View Casual1's profile

Casual1

8 posts in 9 days


#9 posted 06-30-2020 11:07 PM

Why do you need precolor conditioner if you are not staining ?


I am told that natural cherry is at risk of going blotchy when coating. Yes I will be spraying CV, but I figure the conditioner is good insurance against the blotch. From what I can tell it can’t hurt and might help.

-- Guy, San Diego

View LeeRoyMan's profile (online now)

LeeRoyMan

1181 posts in 498 days


#10 posted 06-30-2020 11:31 PM

I see no need for the conditioner. I would rather just keep the one component.
If I was going to use anything else it would be Sanding Sealer.

Instructions: #7- Apply 3 coats. For high-moisture areas, apply 4 coats.

Additional coats will not improve durability.

-- I only know what I know, nothing less, nothing more -- That doesn't count what I used to know..

View Kazooman's profile

Kazooman

1489 posts in 2723 days


#11 posted 07-01-2020 12:44 AM

I hate to raise the issue again, but can anyone look at the fifth board in from the left in the fourth picture and tell me that the OP has lived with this table under a polyurethane finish for years and never noticed the butt ugly “natural” variation in Cherry color? I really doubt that. I know that Cherry has a a variety of colors and that the grey tones can be in the normal spectrum from exposure to moisture and minerals during the life of the tree before and after harvesting. However, the OP never mentioned any issues with the grey color prior to his stripping of the original poly finish. The grey tones seem to be associated with end grain areas leading me to think that it might be the increased porosity allowing infiltration of the stripping chemicals into the wood.

Love it or leave it? I think he lived with the table and loved it for years. The protective polyurethane coating needs renewal. That should not come at the cost of turning a beautiful cherry table top into an ugly blotchy grey. I cannot believe that this is a natural variation in Cherry color that the OP has been stupid enough to have missed for many years. Something happened. He needs a fix to reverse the problem.

View CWWoodworking's profile

CWWoodworking

778 posts in 950 days


#12 posted 07-01-2020 01:17 AM



I hate to raise the issue again, but can anyone look at the fifth board in from the left in the fourth picture and tell me that the OP has lived with this table under a polyurethane finish for years and never noticed the butt ugly “natural” variation in Cherry color? I really doubt that. I know that Cherry has a a variety of colors and that the grey tones can be in the normal spectrum from exposure to moisture and minerals during the life of the tree before and after harvesting. However, the OP never mentioned any issues with the grey color prior to his stripping of the original poly finish. The grey tones seem to be associated with end grain areas leading me to think that it might be the increased porosity allowing infiltration of the stripping chemicals into the wood.

Love it or leave it? I think he lived with the table and loved it for years. The protective polyurethane coating needs renewal. That should not come at the cost of turning a beautiful cherry table top into an ugly blotchy grey. I cannot believe that this is a natural variation in Cherry color that the OP has been stupid enough to have missed for many years. Something happened. He needs a fix to reverse the problem.

- Kazooman

This is a production piece. The small Thin strips and highly varied coloration/grain are a dead giveaway. They waste NOTHING. Even if it’s the ugliest, grayish cherry board you ever seen.

I used to sell a company that would not throw out a dining top unless the defect was dime sized! That was in oak.

View Casual1's profile

Casual1

8 posts in 9 days


#13 posted 07-01-2020 04:55 AM

I hate to raise the issue again,

Thanks Kazooman, but I’ve sanded this a lot and don’t seem to be making headway against the grey. And I don’t know that I’m up to trying to belt sand it or power plane it, so I may be just stuck with it. I agree that it looks to my eyes like an infiltration into the loose grain in the softwood, but I keep expecting it to diminish as I sand, and it’s not.

-- Guy, San Diego

View Kazooman's profile

Kazooman

1489 posts in 2723 days


#14 posted 07-01-2020 11:46 AM


I hate to raise the issue again,

Thanks Kazooman, but I ve sanded this a lot and don t seem to be making headway against the grey. And I don t know that I m up to trying to belt sand it or power plane it, so I may be just stuck with it. I agree that it looks to my eyes like an infiltration into the loose grain in the softwood, but I keep expecting it to diminish as I sand, and it s not.

- Casual1

Tell me one thing. Did the table have the ugly grey blotches from the day you bought it?

If it is staining from reaction of iron with the tannins you will need to chemically treat it to try and get the grey out. You mentioned that your water did not turn black. That’s not how ebonizing works. It is not making a black dye that you apply to the wood. It is applying a solution that reacts chemically with the tannins in the wood producing the black color.

View Robert's profile (online now)

Robert

3739 posts in 2252 days


#15 posted 07-01-2020 01:44 PM

No it’s simply variation in color, common with cherry.

You’ll have to stain the light strips to match. Use the underside to figure it out,

Before you do any staining seal it with dewaxed shellac. Tape off lighter strips to selectively stain. You can also use toner to dial in the color.

Before you do anything you might try treating the whole top with a dye stain.

- Robert

Just a quick question. Are you saying that the OP had all of these grey stains in the finish of his table for all these years as a natural variation in Cherry and never even noticed it? I don’t think so, I think the problems showed up during, and as a direct result of, his finish stripping protocol. You suggest that now that he is going to refinish the table top he should reach out for a fix for his year’s long problem that he never even knew he had? Why would he want to treat the whole top with a dye stain? I think he is trying to preserve the natural cherry color. He wants to remove the grey stains that occurred (not showed up) during his finish stripping process. He does not want to stain (nor paint) the table.

- Kazooman

I don’t think they are stains if you notice, individual boards are affected and there is a distinct line where the glue joint is. I do believe it could have showed up when he stripped it for several reasons. I’ve had this happen to me where after stripping there is one board that looks much lighter & totally out of place

I’m talking about selectively dyeing the light strip of wood to match the rest, not dyeing the whole top.

-- Everything is a prototype thats why its one of a kind!!

showing 1 through 15 of 26 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com