Advice Needed - Failed Tung Oil Finish (Splotchy?)

I applied 2 coats of tung oil to yellowheart wood and got poor results.

My steps:

• sanded boards to 220 grit
• first coat (50/50 pure tung oil & mineral spirits)
• waited 9 days
• second coat (80/20 pure tung oil & mineral spirits)
• waited 5 days and now posting this here

I am a noob with no experience. I am not sure I can even accurately describe the issue, let alone diagnosing the cause. Advice needed. The finish appears uneven in sheen. Along the board you will find patches / streaks that are way shiner than other areas. I would even say that some of those patches / streaks look a bit white and frosty - very unsightly.
In Pictures 2-4, I used harsh lighting and critical angles to highlight and accentuate the problem. Picture 1 shows a more flattering and perhaps realistic view.

Could you recommend a fix without starting over completely? I want to get rid of the shiny spots and achieve a more even / more matte finish.

Attachment 493774 Attachment 493777 Attachment 493776 Attachment 493775

Thank you.

Allen

I would suspect an absorption issue. Maybe sanding differences in some areas vs. others. Wood could be denser in some areas than others. I'm no expert, but I do use tung oil alot and use basically the same method that you use. I have seen absorption issues from sanding differences and denser wood on the same board. I don't know how to fix this problem you have experienced though.

Perhaps more coats will make it more even. I suspect if you rub it out with 0000 steel wool (or a suitable scotchbrite equivalent) it will look very good. "Finishing the finish" is an often overlooked step that improves almost all finishes dramatically, and is usually the best way to achieve the desired sheen, from matte to high gloss.

Those light areas look like contamination or maybe really hard grain. Are you sure there's no glue smeared into the wood in those spots? Or something else? If it's caused by contamination the only remedy is to sand/scrape it to fresh, uncontaminated wood.

John

There is a big difference between Tung oil and "Tung oil finish". What product are you using?
Also, Tung oil (either kind) needs to be sanded in between coats for proper adhesion.
I fear you may need to start over and clean the wood thoroughly before you apply the first coat. I would try the problem area first.

Edward, I used 100% pure tung oil by Real Milk Paint Co. mixed with Solvable (TM) Mineral Spirits

Thx for the suggestion. For starting over, procedurally, does that mean doing the following?

1. wait for the current failed finish to completely cure and harden (is this skippable?)
2. sand down to bare wood
3. vacuum
4. wipe down with mineral spirits (cleaning thoroughly)
5. apply the first coat

Quote:

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Originally Posted by roger wiegand

Perhaps more coats will make it more even. I suspect if you rub it out with 0000 steel wool (or a suitable scotchbrite equivalent) it will look very good. "Finishing the finish" is an often overlooked step that improves almost all finishes dramatically, and is usually the best way to achieve the desired sheen, from matte to high gloss.

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I will buff it with 0000 steel wool and see how things go, do you think I should:

1. just rub the dry surface
2. rub with tung oil - wipe off - let dry
3. rub with mineral spirits - wipe off - let dry

Thanks

I'd do it dry, just polish what's there. Others seem to be seeing things I didn't make out in looking at the photos, so it may not work out, but it's a cheap experiment at this point. The finish does need to be well dried for it to work well.

At first glance, I see WHITE spots. That would suggest contamination. But your description and the 4th pic make me think it's just a sheen discrepancy that you are trying to solve.

If it's just sheen, I would put money on the theory that it's just varying amounts of absorption due to variances in the grain. I wouldn't strip / sand the finish yet.

I would sand the surface with 320 or 400 lightly. Then apply another coat.

The suggestion of steel wool or finishing the finish is a good one, but it's usually done once enough finish has been applied. Varying sheens usually suggests not enough finish having been applied to the whole piece. This is not to say that you should glob it on and try to build a film with the tung oil (that's not appropriate here). It means you should keep applying more until all parts have absorbed as much finish as they will. This is done by applying, sitting, wiping off, and occasionally buffing with high grit sandpaper.

Quote:

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Originally Posted by Prashun Patel

At first glance, I see WHITE spots. That would suggest contamination. But your description and the 4th pic make me think it's just a sheen discrepancy that you are trying to solve.

If it's just sheen, I would put money on the theory that it's just varying amounts of absorption due to variances in the grain. I wouldn't strip / sand the finish yet.

I would sand the surface with 320 or 400 lightly. Then apply another coat.

The suggestion of steel wool or finishing the finish is a good one, but it's usually done once enough finish has been applied. Varying sheens usually suggests not enough finish having been applied to the whole piece. This is not to say that you should glob it on and try to build a film with the tung oil (that's not appropriate here). It means you should keep applying more until all parts have absorbed as much finish as they will. This is done by applying, sitting, wiping off, and occasionally buffing with high grit sandpaper.

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Thanks for your input.

I inspected the boards carefully again and would agree that the issue is likely sheen discrepancy resulting from grain differences - as you and others have suggested.

My goal is purely cosmetic - I would like to eliminate the shiny spots - and just have the entire tung oiled surface equally flat / not glossy.

Does that change the remedy entirely? Or should I still sand + apply more coats?

In fact, you may not even need to lightly sand. I think you want to get more finish in (not on). I realize my description is a little vague. With pure tung oil - or any soft film finish or oil, wipe it on liberally, let it sit on the surface for a minute so it can be absorbed as much as possible, then buff it off casually with a cloth. You don't have to rub it dry, but you don't want any excessively "dripping wet" spots. You keep repeating this regimen for a couple coats (leaving adequate drying time in between). You'd only really need to lightly sand if the dried surface feels a little rough or (worse) gummy.

I'm assuming your "pure tung oil" is not a wiping varnish in disguise.

I agree with Prashun.
I would try his described method, and hopefully you can get enough oil to soak in, so you can build up enough to even out the sheen.
Good luck