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Gray spots on black walnut after applying tung oil finish

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Forum topic by bujaman posted 02-21-2018 06:33 PM 620 views 0 times favorited 10 replies Add to Favorites Watch
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bujaman

5 posts in 580 days


02-21-2018 06:33 PM

Topic tags/keywords: walnut finishing tung oil table

I am building a dining room table and after applying a coat of tung oil finish, some parts of the table took on a greyish hue. You can see the splotches on the attached photo (I started on the bottom of the table top, so hopefully I can get this fixed before doing the top!!). I sanded to 220 and applied the finish according to the instructions. Any ideas on why this is happening and how to fix it? Thanks in advance!


10 replies so far

View CharlesNeil's profile

CharlesNeil

2433 posts in 3985 days


#1 posted 02-22-2018 02:20 PM

What you are seeing are areas that the finish has soaked in , very common .
not sure what “tung oil” your using .. but the key is to get the first coats on and dry, so it doesnt continue to soak in .
Pure tung oils and Blo and so forth dry super slow , and can often be softened by additional coats , so be sure it dry.
You have to fill the porous grain, note the “grey” is around knots where the grain is much more porous .
A good “drying oil ” like Arm R seal, waterlox, minwax wipe on poly and Formbys Tung oil, will definately speed up the process.

So basically the simple answer is you need more finish , however , i hope you are doing the top as well as the bottom, applying a finish to one side can set up adverse drying conditions, and cause it to cup .
some painters pyramids would help , to keep the bottom elevated so air moves uniformly as well .
I often will stand a top like this to keep air movement balanced .

View Gene Howe's profile

Gene Howe

10819 posts in 3543 days


#2 posted 02-22-2018 03:19 PM

Needs Charles’ trace coating, as well. Too late for the bottom, though. Think about it for the top.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

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GR8HUNTER

4531 posts in 827 days


#3 posted 02-22-2018 03:59 PM

you got the best response possible i cannot top Charles :<))

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN

View EarlS's profile

EarlS

1514 posts in 2463 days


#4 posted 02-22-2018 06:10 PM

I only have one item to add. Painter’s pyramids will leave indentations in you table if you use them. Bench cookies will leave an imprint in the finish that is a real pain to et rid of. I usually finish bottom with a day in between coats to let the finish dry out and then flip it over an use some small wood blocks to hold it up while I finish the top. That way if there are any marks from the blocks they are on the bottom side of the table.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View CharlesNeil's profile

CharlesNeil

2433 posts in 3985 days


#5 posted 02-22-2018 06:15 PM

Earls , exactly right , note i said for the pyramids to be on the bottom, should have elaborated .

Thanks Earl. ,
Im not a fan of the cookies,cover too much surface area, and will “weld themselves to a fresh finish .
years ago we used to use “screw boards, ”, would run a 2 or 3 ” screw up threw a piece of scraps and use them the same as the pyramids , they as well left a small divot, but it was the bottom..
the key , is to keep an equal air flow, and balance with the finish .

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bujaman

5 posts in 580 days


#6 posted 02-22-2018 06:38 PM

Thanks everyone for your replies, you have given me a lot to work with.

View Snipes's profile

Snipes

184 posts in 2359 days


#7 posted 02-22-2018 08:22 PM

It looks as if you are trying to make it appear thicker than it is, if so why not on the ends?

-- if it is to be it is up to me

View bujaman's profile

bujaman

5 posts in 580 days


#8 posted 02-22-2018 08:28 PM

There are sliding “breadboard” ends that will accommodate extensions.

View BurlyBob's profile

BurlyBob

5893 posts in 2380 days


#9 posted 02-22-2018 09:37 PM

I made something hold my projects up off the bench. They are small blocks of with biscuits. They’re nothing fancy just functional. I believe I saw them in the Woodsmith magazine. I tried to load a photo but my camera shoots larger than 5mb.

View Woodknack's profile

Woodknack

12329 posts in 2495 days


#10 posted 02-23-2018 01:34 AM

My suggestion is forget tung oil for a dining table, you need a more durable finish especially since walnut is a softer hardwood.

-- Rick M, http://thewoodknack.blogspot.com/

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