Walnut Butcher Block Island / pure Tung Oil after Mineral Oil

[ToddR]

This is my first post so hopefully it's not a dumb question!  I'm new to finishing wood, but read for dozens of hours trying to learn.  I purchased a walnut butcher block counter for a kitchen island.  It was hand made in the USA and arrived fully sanded and oiled with a coat of mineral oil (it's the only option given).  I want to eventually use Waterlox however it's winter and need to do it in the kitchen, thus with the smell and cold temperatures make it a better spring/summer project for me.  I chose 100% pure tung oil (NOT tung oil varnish) mixed 50/50 with citrus solvent and started to remove the mineral oil.   I sanded it down, cleaned it with solvent, sanded it again with 180 grit, cleaned it again with a little Dawn, then started the process per instructions.  Everything is fine, except there are 8 to 10 little areas (1 to 4 inch strips)  that feel/look like a different texture than the rest and have a flat grayish tone to them when looking at an angle.  The areas look dry.  I've applied 4 different days worth of the 50/50 mix each day until it pooled over 80% after 40 minutes, wiped it off with a clean dry rag, let it dry for 24 hours, and did the same the next day.  Now, no matter what I do, those spots remain looking the same.  Most are in strips that look darker colored although a few are in mid-range color areas.  I was told to try to wet sand with a 1 to 2 oil/citrus solvent mix and use 600 grit sandpaper in just those areas to work it in.  That didn't work either after 1 try.  Everything looks great, except these smaller duller light gray toned strips.  I'm starting to think somehow the mineral oil wasn't fully removed in those areas.  I read that maybe it's seepage that dried in those spots, but  who knows.  I'm a rookie at this obviously.  I'm not sure what to try next.  Sand all of those spots way down and try to spot fix them from bare wood again?  Just give up and use Waterlox in the spring? Use Arm-R-Seal and be done with it and have it sealed and less natural looking?

Any tips or ideas would be appreciated.  

[drzaius]

A picture really is worth a thousand words.

Personally, I would not try to apply any sort of finish over mineral oil and getting rid of the mineral oil will be a problem. Think about trying to paint a car that has motor oil splattered all over it. Mineral oil never, ever polymerizes, so it will always be oily. Repeated washings with mineral spirits followed by wiping down with naptha or acetone may get the surface free of oil long enough to apply a coat of shellac or poly. Even so, there will probably be spots that retain enough mineral oil to spoil the finish.

[ToddR]

Yeah I've definitely heard that online before.  I checked with the Waterlox company and Real Milk Paint company and both said if I sand down with 180 grit and clean it well and let it dry, it should be fine and the mineral oil shouldn't disrupt the application.  Same with the company in Wisconsin where I got the top from.  They said they only put 1 thin coat of mineral oil for shipping so it doesn't dry out and that removing it has never been an issue.  Hard to say I guess.  Here is a photo of what it looked like but I may have figured something out last night.  I decided to start over so I sanded it down again 2 times with the 180 grit, cleaned it and let it sit.  I cleaned the difficult spots with liquid Dawn.  Nothing was seeping out after an hour except a two light colored wood areas which were actually very lightly seeping the tung oil/citrus mix (I smelled it).  Those areas weren't the problem areas.  Anyway, I reapplied a pretty heavy mixture of tung oil / citrus and wiped all the excess after an hour.  This morning I noticed about half of the original difficult spots were starting to get that gray dull finish again when viewed at an angle so I wiped them with a fresh cloth and it seems those are areas where tung oil is seeping up and starting to dry gray on the surface!  After wiping them off, those spots looked good again.  

When I get home from work I'm going to keep wiping those gray areas and hopefully this will be the fix to the problem.  I'm not sure it will but I hope so.  I read on another site someone say that tung oil can seep from areas that have larger pores and if it dries on the surface it can get a dull gray sheen to it.  Let's hope that's what's going on!  I'll report back after a few days.

[drzaius]

I have learned the hard way that a penetrating oil finish can seep out of pores for days after application. The only answer is to wipe the surface down every couple of hours until there is no more seeping. But I've never seen it turn grey like that. There will be little specs of oil that come to the surface & if left un-wiped, will eventually cure to form shiny, sticky spots. I'm guessing that the grey is a reaction to the mineral oil, water, or dish soap.

[Byrdie]

When I look at the pictures I see that the top is a lamination of multiple boards and for the two areas pictured I see a definite, consistent pattern to the grain.  I'm not ready to pin this as the cause but those boards are different in makeup in those locations and both look like points at which limbs exited the tree.  Not being as savvy on the wood its self as some others here, I'll leave it to them to run with my suggestion that something in that specific grain causes a difference in the way the finish is being accepted.

[ToddR]

Yeah that's is a good description of the wood.  Butchers block is always all sorts of different color pieces and textures of wood within that wood type. The top came from a very reputable place who hand makes them so I'd hope they wouldn't use pieces that had some sort of flaw where it wouldn't accept the oil.  It's a good hypothesis about the branches, but I'm leaning towards it being an issue with seepage and drying on top instead of inside the wood.  I do agree with you that part of the problem in those areas is that they are a different grain from other planks in the top.  They seem harder and darker and have more tiny pores.

When I got home from work a bit ago, almost none of the gray has returned since I re-sanded and re-applied the oil and then wiped they gray areas again this morning.  There were a few tiny areas that looked like they were starting to turn a bit gray.  There weren't noticeable dots of oil in those areas, but I wiped them down again with a clean rag and they look good once again.  No gray.  The rag came away with a light brown tint the color of the tung oil so I'm going to follow dzraius' advice and keep wiping the spots for another day and see if it stops seeping and the gray stays away.  There were other areas with little dots of oil too but those were in areas that didn't turn gray at all. 

[ToddR]

This morning, almost no gray areas.  Just a few slightly graying spots that I wiped again.  No other seepage either.  If it stays this way, tonight I'll put on the 2nd coat.

[AceHoleInOne]

Don't put more oil on, call it done. If the wood is still pushing up oil after a few days, it's done, over move on.  The wood can't take anymore. 

Your real issue may be the soap and water (dawn) down in the grain causing the "grey" let it be, let it dry and enjoy. Never flood the wood and leave it set on top. Multiple light coats allowing good drying between coats.

-Ace-     

[ToddR]

I used a tiny bit of dawn at the recommendation of the Real Milk Paint company and didn't saturate the top with soapy water (the rag was literally just moist), but I suppose it's possible that the dawn seeped deeply into those spots and is reacting to the mineral oil.  I would guess it's not reacting to the tung oil as hopefully the RMP company know their own product and wouldn't have recommended something that would react badly.  I guess it's hard to say for sure.  When I cleaned those areas the second time however when they were gray, they didn't suds up or show any signs of soap at all.  I have read on multiple forums though since posting this, that at times, Walnut is known to have some issues with 'blotching' which produces  small gray areas.  Someone said it was due to the oil drying on the surface from not sanding enough in those spots.  Maybe that was part of the issue which is why after re-sanding it's not having as many issues.  I think by re-sanding, I was able to remove a bunch of whatever was causing the issue in those spots.

No worries, I never flooded the top with the oil and let it sit there for more than an hour or two.  I followed what the RMP company said to do exactly.  I applied it liberally the 1st time so it was all shiny, waited 40 minutes, fed the dry spots, waited 40 minutes, applied to the dry spots again, etc...until no dry spots appeared for 40 minutes.  Then I completely wiped it down so no oil sat on top at all.  They say do it again the next day as well until no dry spots appear.  I did sand it down the other day, so in reality there's only 1 day of application, although I'm sure I didn't sand it down to where all the tung oil soaked deep in.  Anyway, at no point this time was there any seeping up at all except for 1 or two two or three inch spots.

Here are the instruction from the Real Milk Paint company for their 100% pure tung oil.

https://www.realmilkpaint.com/blog/tutorials-videos/beginners-guide-pure-tung-oil/

 

[AceHoleInOne]

Using the "dish soap" is for cleaning the surface after it has fully cured, specifically, cleaning the surface from soils of daily use. Using it before/during the finishing process would more than likely cause finishing issues and the grain to swell...oil - water/soap don't play nice.

Dawn dish soap is a degreaser. 

Wet sanding with 600 paper over the "bad" spots of the more porous spots would slow the absorption of the oil, so the oil couldn't penetrate as deep thus slowing push back. Also, wet sanding (spot sanding) those spots could cause an oil/ wood slurry to be force into the grain potentially causing  color change.  

-Ace-

[ToddR]

yeah that makes sense.  They told me to use some dawn to remove the mineral oil since dawn is known to wash oil off.  I can't say if they've successfully done that or not but I'll mention it to the Real Milk Paint folks and tell them that using dawn to remove the mineral oil might not have been a good idea.  Or maybe at least ask them if that could have been a bad recommendation.  I don't want to piss them off since I don't know for sure that caused the problems in those particular spots.  They also were the ones who told me to try to wet sand at 600 to fix the bad spots (which obviously didn't work).  Keep in mind, the color change happened well before I did the wet sanding so that didn't cause the color change. 

Either way, it seems re-sanding all of it with 150 again and cleaning with the Citrus Solvent only and then wiping those spots over a day or two seems to have fixed the issues thankfully!  Whatever bad stuff was in those spots seems to be gone...at least for now.  I may just seal it all up with Arm-R-Seal or do the Waterlox in the spring to seal it all up.   

[Byrdie]

Knowing that the block had been shipped with a protective coat of mineral oil, using a very dilute mixture of Dawn to clean it made perfect sense to me.  We now know that the gray spots were occurring where you were getting unbalanced absorption of your oil finish.  I still believe that the grain of the laminate pieces in those specific spots had something to do with it.

At any rate, I think the point Ace was trying to make in his original post was related to your stating that you were going to apply a second coat.  You are already getting evidence that balance has been met with the amount of finish you're removing.  I believe his point was that it's not necessary to add any additional coats, max penetration has been achieved. 

I believe he may have also been suggesting that part of the reason you were getting the gray spots was the use of the Dawn cleaning prep and that either too much detergent may have ended up in those spots and/or not have been properly cleaned in those spots to where it was causing a reaction with the oil and therefore the discoloration.  Possible but I lean toward the grain in those areas having a different porosity and therefore causing a different absorption rate of your finish.

[AceHoleInOne]

On 1/28/2019 at 3:58 PM, ToddR said:

 I sanded it down, cleaned it with solvent, sanded it again with 180 grit, cleaned it again with a little Dawn, then started the process per instructions.  Everything is fine, except there are 8 to 10 little areas (1 to 4 inch strips)  that feel/look like a different texture than the rest and have a flat grayish tone to them when looking at an angle. 

Sand-Solvent-Water and Dawn....the question is... how long did the dawn and water allowed to dry? The water and dawn was more than likely pulled down into the grain and not allowed to completely dry. 

Did they tell you to go over the wood with Dawn after using the solvent? Different texture = raised grain from water and dawn...

 

-Ace-

[ToddR]

They said use the solvent or Dawn so I sanded, used solvent, sanded, then used dawn.  That could have been a newbie mistake to use both but it's what I did.  That said, I did what Byrdie mentioned and used only a tiny bit of watered down dawn and only moistened a rag with it to clean and then immediately wiped as much moisture off as I could because I figured the goal was to get the dawn to lift the oil out, not to let it seep in or saturate with water/dawn.  I had read it could raise the grain and just thought it was bad to have any amount of water on it for long. 

The texture of those areas looked more porous in that I could see pores but it felt as smooth as the rest if that makes any sense from a 'newbie' type description.  It didn't feel rough compared to the rest just tiny pores I could see and feel.  

What you said about letting it dry may be the key...I only waited a few hours and while it felt dry, it probably wasn't fully dry. 

Ace, do you think that after the re-sanding and cleaning with just the citrus that I did, that the one day of oiling is sufficient even though they say on their website to do two days?  Maybe that re-sanding isn't truly like starting over and the previous few days of oiling plus this one is enough.

[AceHoleInOne]

Your goal was to apply the oil to give it protection until you get the chance to put a better coating on when weather changes. I probably would be good with the mineral oil as it came from manufacture, maybe freshen it up a time or two, with very thin coats until summer.

The wood tells you when you're done. Nothing is steadfast, those are guidelines. Re-sanding and reapplying is not starting over...oil is still soaked and inside the wood. You're simply sanding off the exterior of the dried surface. Finish makers give you guidelines as to when a finish is fully cured, why, because they know the finish is still wet inside the wood. A finish while dry on the outside to the touch, the inside is wet and has to gas off through the exterior coat that is still trying to fully dry. Hence the exact reason you don't want a smelly kitchen in the winter.  

I think what happened, the porous grain pulled in the soap/water..you don't even have to flood the surface, it just does. It felt dry to the touch then you began your finish schedule applying the oil over the water/damp grain, water-oil get grey.

Just leave it be, keep an eye on it. Keep spills cleaned up. This summer, probably wash it down good with mineral  spirits and steel wool. Let it dry a good week (the wood is thick and will drink and retain the mineral spirits)

Give it a good sanding,  apply the Arm-R-Seal.

-Ace-

 

-Ace-

 

 

[ToddR]

I wanted to provide an update.  So I took Ace's advice and didn't apply anything further.  Each day I wiped the gray areas and found I was able to remove it with just a few light wipes of a clean cloth.  After doing this for the last 10 days, the gray is completely gone and has not reappeared for 5 days!  Now I'm just wiping any occasional oil spots seeping up (only a few tiny ones a day) and waiting for it to fully cure.  In the late spring I'll do the waterlox probably on the top & sides.  I'm assuming I don't need to take off the top and re-do the bottom.  Thanks for the help everyone with this gray issue. 

[drzaius]

That's good to hear.

[AceHoleInOne]

If you want, you can coat the bottom when it's time. I don't see the need to. The block top is glued together and all those glue seams should keep your top stable and prevent any significant movement. 

Glad to hear it's shaping-up

 

-Ace-