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I made a mistake when applying a dark oil stain on a T&G cedar ceiling, and I have lap marks which I would like to remove.

The 6-12in laps are notably darker if viewed from certain angles. The stain was applied about 7 days ago. It's an oil based Minwax stain, and the area is about 150sqft.

Some options I'd consider are:

  • sanding and redoing
  • clean with thinner

I don't want to apply a gel stain, or redo with a darker stain.

Since sanding is quite messy and somewhat laborious, it's not my favourite option yet.

How effective might the thinner be, what's a good thinner for the stain on cedar substrate, what's the technique, and can it be used in combination with sanding, to reduce the amount of sanding required?

On other ceilings I applied the Minwax stain successfully by working in full lengths of the cedar T&G planks, which is how I would do it again, The oil stain on cedar is quite beautiful. The trick is to finish full lengths while the stain is still wet, and apply long streaks with a brush.

But I am stuck with the section of ceiling that was done wrong.

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    Pop on over to Woodworking for loads of info on finishing and fixing finishing issues. Might be a good idea to ask that this be migrated there.
    – FreeMan
    Jul 12, 2022 at 14:00
  • @FreeMan good tip. I now looked there but found nothing related. Perhaps I'll repost there later. Let's keep this one here for now. I'll get a chance to tackle the problem in a few weeks again.
    – P2000
    Jul 13, 2022 at 21:02

2 Answers 2

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sanding and redoing

I'm going to guess this would produce a better result than a thinner.

clean with thinner

No clue, I have zero experience with this.

You can try recreating the issue on non-installed material and test out this idea to get an idea of the results.


Third option, remove and replace the boards and re-stain.

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    Except that stain is supposed to soak into the wood, not sit on the surface like paint. There will likely be a lot more sanding than expected to get back down to bare wood. Also, it's difficult to sand it down evenly.
    – FreeMan
    Jul 12, 2022 at 14:01
  • @FreeMan I never claimed that doing it right would be easy. Are you suggesting the "thinner" route?
    – MonkeyZeus
    Jul 12, 2022 at 14:22
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    No, I'm not suggesting any route. This isn't an easy problem to solve, thus my suggestion (comment on OP) to check out Woodworking as there are many questions like this over there and a lot of knowledge and wisdom on the topic.
    – FreeMan
    Jul 12, 2022 at 14:29
  • "try recreating the issue" smart idea. I'll try and report back when I get to it again in a few weeks.
    – P2000
    Jul 13, 2022 at 21:00
  • just a quick update: I tried thinner first, it was tedious sponging/rubbing above my head and not effective. Far more effective was sanding a bit to lighten it (not bare) and re-staining thinly with a cloth to even & match. I'll update my question later when done. So far your answer seems correct.
    – P2000
    Aug 4, 2022 at 18:28
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I have successfully removed the lap marks, and this answer summarizes my personal experience.

The Manufactuer's Recommendation: Thinner

The manufacture recommended using thinner when I called them about these lap marks. This did not work for me. I tried thinner, first on a cloth making no visible progress, then sponging it to be able to better soak the wood. This was work above my head, very messy, and the fumes were literally noxious. The results also disappointed.

I think the "thinner" approach could thin out lap marks on harder wood (harder than the cedar T&G of my ceiling) and when working on horizontal or maybe vertical surface, for instance on a work bench in a wood shop.

It is also useful to note that the thinner can be applied well after the stain has dried. The stain deposits and penetrates its tint into the wood, where the tint is left behind after the solvent evaporates. The tint does not cure like paint would. So applying thinner can release the tint even weeks later. The difficulty is soaking the wood deep enough to dissolve the tint and then soaking it up with a cloth. With soft and porous wood like cedar, the stain will have carried the tint deeper into the fibre making later removal very difficult.

My Preference: the Sanding Approach

What did work well, as proposed in the other answer, is to sand. You don't have to sand bare. The trick is to sand lightly so that some of the stained surface of the wood is removed, thus lighting the lapped areas.

If necessary, first mark of the darker and/or lapped areas by observing it from afar under different angles. When it comes to ceilings, what you see with your nose on the wood standing on a ladder or scaffolding is different from what your critical family members might see from the floor under different angles. And while working a ceiling area it's good to get continuous feedback from someone down below.

It is also a good visual distraction to mark off full lengths of board. So if there is a seem of butting boards nearby, continue to that seem. The most unappealing effect of lap marks is when they lign up across boards. Breaking it up with lighter runs helps too, even if the tinting along the board doesn't precisely match with the surrounding boards.

  1. Mark the area that needs treatment. View and verify from different angles.

  2. Sand it with light pressure using coarse grit sandpaper wrapped around a sanding sponge: the stained cedar dusting will otherwise quickly clog the sandpaper. Do not use a wood block or just your fingers. I used 60 grit. Work in lengths of the grain, and if possible feather the sanding action out beyond the lapped area, but work the lapped section meticulously.

  3. Apply very lightly some of the original stain on a lint free cloth (e.g. piece of old bedsheets) and rub it in where you sanded. This removes the sanding dust and deepens the tint by removing the whitening caused by abbrasion on the surface of the stain.

Some of the wood will have a strained look (lighter strands of wood fibre stand out) due to the sanding, and this step also evens out such strand discolouring relative to the surrounding area.

Do not be afraid to redo sections. It took me sometimes 2 or 3 repetitions of sanding/staining to get it right. Always check from a distance.

I accepted the earlier answer suggesting the sanding approach as the best answer, and I am providing this answer of my own to share some more details and perspectives.

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