Weeping oil problem


SimonPrutton

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I’ve got a sapele project that I have just finished with danish oil. I’m getting some really ugly spotting on the surface though…what can I do to eliminate this? I would add a photo, but I can’t make the photo upload work. It looks as though the wood is saturated at these spots, which appear to follow the grain. Any suggestions?

 

 

Edited by SimonPrutton
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@Simon, that sounds like what is commonly called "blotching". It occurs when wavy or swirling grain absorbs finish unevenly, and is most pronounced with stains or tinted finishes.

Common preventive measures include sanding to very high grits, and sealing the surface with a non-coloring "wash coat", such as well-thinned, dewaxed blonde shellac, prior to adding a top coat, especially if a colorant is involved.

I can't think of a simple way to remove blotch, short of starting over, but there are more expert finishers here that might have something to offer.

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Thanks wtnhighlander. I had already assumed I’d have to sand it down to re-apply. What I am seeing after sanding is the oil coming back up to the surface from below…how do I combat that? Any suggestions from other experts would be appreciated too…I’ve put too much work into this to give up.

I’ve also added the photo I took earlier, at the time of my original post, if that helps.

075D4B5C-22A7-48EA-8963-964E3E77C341.jpeg

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Need some really important information. What finish are you using? How are you applying the finish?

The spots look like a finish was flooded on and wiped back. Sapele is a porous wood and this is what will happen depending on the finish that is being used there may be techniques to correct this.

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Hi Chestnut

Thanks for taking the time to reply.

The oil I am using is this: https://www.furnitureclinic.co.uk/danish-oil?options=cart

I poured & sponged-brushed the first coat, which caused this problem I think. Wiped on with a lintfree cloth a very thin 2nd coat after lightly sanding to try to repair…that is what is in the photo above. The oil oozes out again after sanding though, so I am concerned about how to eliminate this, now that I’ve saturated the wood.

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On 6/13/2022 at 5:33 AM, SimonPrutton said:

What I am seeing after sanding is the oil coming back up to the surface from below…how do I combat that?

I have always called that "weeping".  This is oil coming up from the pores after a flooding sort of step in finishing. The cure is to keep wiping them off until they stop.  Red oak can weep for days if heavily flooded.  If there was uncured finish that got trapped somehow, that may be what you are seeing.  Another anomaly of wipe on finishes is that some areas of the wood soak up more than others so multiple thin coats are required to reach an even absorption and appearance.  This also may be what you are seeing.

When using these products I would apply lighter coats.  You may find that you reapply to certain areas many more times than other areas.  Evenness is what you are after in contrast to thickness of application at the first stage.  Once you get the entire surface evenly wet (view with raking light for easier dry spot detection) you would generally wait 15 minutes or so and then wipe ALL the excess off.  If that means 4 return visits at 1 hour intervals to eliminate weeping, that's what it means.  As you (and I) have learned it takes less time to wait till a coat is "ready" for the next coat than to go back and try to repair. 

In ideal conditions oil blends take 12 to 24 hours to dry.  Variables in air temp and moisture effect this.  I assume from your link that you are in the UK where it is a but damp.  Your product states quick drying which probably just means it contains metallic driers to speed the process.  This is fine and I often add a bit of Japan Drier to my own blends. 

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Hard to say for sure just looking at one picture, but those spots look like tear-out to me. Tear-out is not uncommon in areas of changing grain direction like that and it occurs when planer blades are cutting against the grain and actually "pull" out small chunks of wood rather than cutting it.

Take a close look at the individual spots with a magnifying glass and tell us what they look like. If they are tear-outs, you have some other measures you need to follow other than just finishing.

It looks like they may be filled with sanding swarf now. Clean that out first.

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I can’t check right now but will look closely later. I don’t think it will be tear out but worth a closer look.

Thanks to everyone who commented so far…you guys are fantastic!

As a point of clarification on how to proceed, assuming it’s NOT tear-out, it’s still “weeping” an hour ago…and the areas that have wept are darker spots and I’d assume they will weep again if I apply more and I can’t see how I get an even finish.

I can see how the advice above helps me if I were starting from scratch but I am struggling to see how to get the piece clean enough to apply that advice. Or am I missing something?

Simon.

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I just happened to be applying a tinted oil colorant to part of a project this morning.  I apply it lightly as I described above to an even wetness, let set and wipe it off.  If I want a deeper color I repeat as required.  I want a light coloration on this piece so 1 shot is enough.

I come back every 10 minutes or so till the weeping slows down then I come back every half hour or so.  About an hour in I noticed something that looked familiar.

428438782_Float-Med-Cab(193).jpg.94ee0e5339313abd225550be087b05ea.jpg

This is what I am watching for on my return visits.  When I see it I wipe it away.

937983131_Float-Med-Cab(194).jpg.ce93fa0569ad5c6dab9d788ea99540df.jpg

Even though there is weeping at several location on the 18" x 46" piece the total effect on a clean paper towel is this.

408549725_Float-Med-Cab(195).jpg.a0180e03a1a2ab5cac2341e2a1d169fb.jpg

As you can see, even though the visual effect is significant it doesn't take much weeped finish to do it.  I continue checking back and wiping until the weeping stops, check the clock and give it 24 hours.

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After seeing the photo, I agree with @gee-dub. My first experience with a linseed oil finish was a table made of red oak. I followed the suggested "flood, wait, wipe" schedule, but the very porous oak soaked in so much oil that it wept stalactites of congealed oil from the underside of the top for almost a month.  In that situation, I found scrubbing it with a mineral spirits-soaked rag to be more effective.

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  • SimonPrutton changed the title to Weeping oil problem

Don't feel too bad, OP. I think most of us have learned that lesson the hard way. Some woods (red oak, lookin' at you) have such open pores that it can literally take days for all the excess oil to seep back out to the surface. All that while, it needs to be wiped off before it can get tacky. 

I love the look and feel of a penetrating oil finish. When I use it on porous woods, I don't flood it on to the point where it can really load up the pore. I wipe it on every few minutes with a cloth that is not overloaded with oil. Just enough to wet the surface. Do that until it isn't slurping up the oil anymore. Then give it a final wipe after 10 or 15 minutes. Oops, I should not have said final, because you still need to check back every half hour or so and keep wiping until no more weeping. 

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