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Gray splotches on Ash mantle

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Hey Helpers! Mr. Rogers always said to look for the helpers in any crisis...so I’m searching diligently for some advice on my recent mini crisis. (Definitely a first world problem) 

I have a beautiful ash mantle firmly attached above my fireplace.  Flat on top & bottom. Worm tracks/tunnels (this non-technical verbiage reveals my skill set) are on front edge. When it was mounted above the fireplace 2 years ago, 2 coats of Danish oil were rubbed onto this raw wood. Lovely.

Recently, it became dull & rather dried out. We’re too busy with jobs & kids to keep treating it with Danish oil so I sought some advice from a woodworker friend. He advised:

1. Lightly rub with Mineral Spirits on a rag.

2. Put 2 thin coats of Minwax Polycrylic. Satin 

I did step 1.  Let it dry extensively. Then did 1 coat of the Polycrylic & let it dry overnight. Much to my sad surprise the next morning, there were gray splotches intermittently on the front wormy part . Not on the top or bottom. A gray,  hazy film on both ends but densely splotchy on the front, textured part. A pisser. What to do?

I took the Mineral Spirits & once again, rubbed down the front, worm trails surface. Miraculously, it was damp appearing and seemed to clear! Kept my fingers crossed & said a prayer... Nope. Once it dried, the big gray blotches were back.

Google searches have proven unsuccessful & now I’m unsure how to proceed??? Any suggestions?  

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I don't use water-borne finishes like polycrylic, but similar symptoms show up here from time to time, usually attributed to moisture under the finish. Another possible cause is incompatability between the Danish oil and the Polycrylic.

I would avoid applying any more finish until a reasonable cause is identified. 

For future reference, it is a good practice to add a coat of shellac as a "universal sealer" between finishes of different types. 

Hopefully, one of the pros will have an easy fix to suggest. All I can offer is a bottle of citrus stripper and a toothbrush....

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Thank you for your quick response & taking the time to help me wtnhighlander!  I appreciate any input I can get!

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I love the bug tunnels under the bark & find them much more interesting than just the regular live edge. But sorry, I have no suggestions for a cure the gray splotches.

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There are some good finish experts here and I sent a message to one with a link to your post here, hopefully they will check in on this.

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25 minutes ago, drzaius said:

I love the bug tunnels under the bark & find them much more interesting than just the regular live edge. But sorry, I have no suggestions for a cure the gray splotches.

I know! I love those tunnels too. I’m concerned the integrity of the bark will be compromised if I have to do anything drastic to clear the blotches. Thanks for your feedback!

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23 minutes ago, Chet said:

There are some good finish experts here and I sent a message to one with a link to your post here, hopefully they will check in on this.

You people are amazing! This is my first time on this forum and I can’t believe how kind you all are to try & help me. 

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Has it changed at all since the first morning after?   I would be tempted to try a heat gun on one corner of it, to see what it would do.

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No, Tom it really hasn’t changed as far as I can tell. Went right back to the same blotches after the Mineral Spirits application dried. What do you anticipate will happen with the heat gun?

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I don't know.   It's just the first thing I would try.   You don't want to put enough heat on it to change the color of the wood, but it might bring out what's locked under the top coat, or soften it enough to get it off.  I would try just a small spot over on one edge.

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Man, that’s not good!  I would contact Minwax and tell them what you told us. Good luck and welcome to the forum. Oh, and let us know your outcome. 

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9 hours ago, Tom King said:

I don't know.   It's just the first thing I would try.   You don't want to put enough heat on it to change the color of the wood, but it might bring out what's locked under the top coat, or soften it enough to get it off.  I would try just a small spot over on one edge.

Thanks Tom! I may give it a try!

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This sounds very similar to the issue another poster was having with the oil finish on his walnut counter top recently.  It sounds like the oil finish wasn't completely done off-gassing (two years sounds wayyyyy too long for that to be possible) and sealing it in with a poly coat or varnish is now showing the trapped gasses.

Ace was the one with the best answers on that last set of posts so hopefully he'll chime in here.  I understand the chemistry somewhat but have always hated finishing just enough to keep it really simple so I might not be the one with the best answers on this.

edit: check the very next topic to see what I'm talking about ...

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Hard to tell from pic,  but are the grey areas actually raised...possibly raised and full of sawdust left behind from previous insect activity? Can you take your finger and pick them off?  

 

-Ace-

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If it's skuts and fugs left behind from bugs or possibly a bit of bark. I would lightly use a wire brush and clean those areas then give the entire front a brush to match the surface. The wire brush may scratch / give texture to the surface a bit. Go easy. Don't use mineral spirits to clean. Then re-coat.

The problem may of been the mineral spirits was still wet in the wood/bark/sawdust. The topcoat you used is a water-based product. Mineral spirits (still damp and or gassing off in the wood) and water-based finishes don't play nice. 

I know this isn't the answer you'd like to hear about a wire brush, but perhaps after you remove the gook, you can take a bark colored finishing  marker or and highlight some of the tunnel edges and give it a bark look?

 

-Ace-   

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Thank you Ace! I greatly appreciate your time & assistance. I contacted Minwax yesterday & they suggested using a blow dryer. Didn’t work. Then, light sanding. Didn’t work.( So no, you can’t pick it off. It’s crusted on) Now the recommendation is for Citrus Stripper followed by a wipe on poly. Going to give it a try. Does that sound like a viable option in your experience? If that doesn’t work, I’ll give the wire brush method a Go. You’re right, I don’t relish the thought of scratching up the textured surface. That is the whole reason we went with the ash in the first place. Thanks again. 

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K Cooper, Mark J and Byrdie...thank you for your concern & helping in my dilemma! I’m open to any suggestions. I’ll keep you posted if it gets figured out. Thanks again. 

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Are you going to strip the entire piece? Spot stripping could turn out to be a disaster with the top edge.  The chem strip will more that likely remove and soften the bark. You will have to use steel wool to remove the old finish by scrubbing. The bark/tunnel/sawdust is the issue and should be removed. 

Most folks on those live edges will use a power drill and a wire wheel to clean off. 

 

-Ace-   

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Ugh! I will certainly trial it on a small portion before moving forward with the entire textured face of the mantle. It appears that there are no easy fixes! Sheesh. Thanks Ace!

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Interesting that they had the same sort of idea that I had.   If you have a heat gun, I'd still try it.   Maybe a little more heat than a hair dryer can produce might do it.

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If it doesn't soften the finish enough to allow what's under it to outgas, have a clean rag handy, and wipe it, just to see if you can get it off.  Don't put enough heat on it to change the color of the wood.  If the finish starts smoking, you've stayed on it borderline too long.  Wear a respirator.

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Good to know! Thanks for the details since I’m a novice. I won’t be able to tackle this project for a few weeks now. But, I’ll keep you posted! 

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