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I'm building a table (first time with hardwood!) and was wondering if there's anything 'wrong' with using the following combo:

Danish oil (or similar), then de-waxed shellac, and then General Finishes' Arm-R-Seal or High Performance satin on top (both are poly).

I'm going to try this out on some sample boards, of course, but was reading up and trying to see what would give the best durability with the Danish oil first coat. I've read a dewaxed shellac will help the topcoat dry quick and is a good sealer, but wasn't sure beyond that what the benefits were. Thank you!

Graphus
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markthethomas
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    The woodworking stand exchange may be a better fit for this question. – Alaska Man Jan 22 '21 at 03:32
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    Agreed! This may actually be closed as a duplicate at [woodworking.se]. Head yourself over there and search for your finish types, and look through the [tag:finishing] tag. You'll find lots of great info there, and your questions may already be answered. – FreeMan Jan 22 '21 at 12:17
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    Hey Mark, if you join Woodworking welcome. If not I hope you get to read this. There's nothing wrong per se with what you plan as your finishing schedule, but there's likely no benefit to doing this 3-stage process. Is there some specific reason you thought you should use "Danish oil" first, and not go straight to the varnish? Some woods get a slight buff if oiled before poly goes on, but it's slight. In most cases there's little visible difference (or none) making it usually a needless extra step that adds time unnecessarily. – Graphus Jan 23 '21 at 08:58
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    "I've read a dewaxed shellac will help the topcoat dry quick" Not sure where you read that but you might not want to rely on that source again as it's dead wrong on this point. – Graphus Jan 23 '21 at 08:58
  • @Graphus i think that advice comes from wikipedia, the same site that claimed for almost a year that the big Paul Bunyan statue in Minnesota has "an actual moose knuckle in his trousers" (https://en.wikipedia.org/w/index.php?title=Paul_Bunyan_and_Babe_the_Blue_Ox&diff=868716929) – Z4-tier Jan 23 '21 at 14:53
  • @Z4-tier, thanks. Wikipedia obviously suffers from the non-specialists who have free access to edit (or create) material, but I wouldn't be surprised to hear this was on a dedicated woodworking site of some kind to be perfectly honest. There's buckets of misleading and outright wrong info out there from all levels of sources, including genuine pros and time-served professionals like Paul Sellers. – Graphus Jan 23 '21 at 17:25
  • @AlaskaMan ah awesome! wasn't aware. Thanks for migrating! – markthethomas Jan 24 '21 at 02:43
  • @Graphus been doing research on some various approaches to see what the ideal final outcome will be (this is for a table that we want to show off etc.) and have seen different info in different videos/articles/etc. :) the actual "I've read a dewaxed shellac will help the topcoat dry quick" source was in a few videos, but weren't the main thrust of the content — possible that they didn't mean to communicate what they did. I'll do a couple test squares w/ the arm-r-seal and see how they look vs the danish oil. Going for a darker look overall – markthethomas Jan 24 '21 at 02:45
  • thanks all for the advice so far! It's been hard to find good advice/info on things. There is definitely lots of older forum content that is hard to gauge, haha – markthethomas Jan 24 '21 at 02:47
  • Just on the shellac and drying times, a waterbased topcoat is perhaps the best example as it will actually slow the drying time..... because it makes the wood less absorbent, and waterbased finishes literally dry by drying. A lot of that is of course water evaporating into the air, but unfinished wood is free to absorb the water too. Now this doesn't mean you wouldn't choose to shellac first in this case — it's advantageous for a number of reasons — just wanted to give the clearest example of where it would do the opposite. – Graphus Jan 24 '21 at 10:25

2 Answers2

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was wondering if there's anything 'wrong' with using the following combo

There's nothing wrong with it per se, but there's no reason to use all three finishes.

"Danish oil" type products1 can be used as finishes in their own right, as of course can Arm-R-Seal or High Performance. So the only reason to use a straight oil or blended oil finish first would be if it gives you some benefit. On many woods there's so little visual difference that it's just not worth the extra step and the added wait time; and frequently there's no improvement in appearance at all. As for the shellac, it's simply not needed here since oil-based polyurethanes are fully compatible with "Danish oil".

So in short, you can apply oil-based varnish over "Danish oil" if you want but just applying the varnish straight onto the wood may yield almost the same, or even identical, results with one fewer step.

Incidentally for ease of application and greater assurance of a good result (virtually foolproof in fact) I would suggest converting the varnish to wiping varnish and applying it that way. Read more about that in this previous Answer.

I'm going to try this out on some sample boards, of course, but was reading up and trying to see what would give the best durability with the Danish oil first coat.

Good to hear, it's always a good idea to do samples first. Not testing finish before committing to your project pieces can lead to poor, occasionally disastrous, results even when using finishes you have used before so it's absolutely vital when using a new finish or finishing procedure, or you're working with a wood you're not familiar with2.

So IF you can see an improvement in appearance using the "Danish oil" first it's worth noting that straight linseed oil3 will in general give an even more noticeable change. It's for this reason that I occasionally oil first, and then apply shellac or varnish on top for gloss and durability. If I use a finish similar to commercial "Danish oil" it would typically be the entire finish.... to my mind there's no reason to use an oil/varnish blend otherwise.

1 These are typically a blend of oil, varnish and lots of solvent. Incidentally I always put this in quotes because it's not from Denmark and actually has no real link to the country.

2 A great example here would be if you're used to staining and finishing oak and like the results, then use the same process on birch without a test first. To say the difference in result would come as a surprise is a huuuge understatement!

3 I mean boiled linseed oil (BLO) here, not raw linseed oil. Raw oil is usable here but takes too long to 'dry' to be practical.

Graphus
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  • Danish oil is usually just Tung oil which I believe is from China & India. It's always some other type of drying oil, rebranded as "Danish", so it's better to just buy something where you actually know what's in the can. BLO is good, and it can be thinned pretty aggressively with mineral spirits. It's great for old windows since it's one of the main ingredients in glazing putty; applying it to the raw wood keeps it from wicking all the oil out of the putty. – Z4-tier Feb 02 '21 at 06:53
  • @Z4-tier, not sure what you meant to say but your first sentence disagrees with the one that follows. As for "Danish oil", it is typically as I described (the first versions were always this, copying the first one on the market back in the 50s I think it was). More recently companies seeking lower-VOC versions of things have labelled different things this way, further confusing the already obscure and confusing finishing market, but most consumer versions remain dilute penetrating oil finishes with a varnish component. – Graphus Feb 02 '21 at 09:27
  • Danish oil is whatever they put in the can; usually, Tung oil. Tomorrow, maybe something else. – Z4-tier Feb 03 '21 at 17:27
  • @Z4-tier, yes indeed it can be whatever they put in the can. But it will rarely, if ever, contain any tung oil. Tung oil is too expensive to use in a consumer-level finish of this type (even with the heavy dilution that is typical, >50% solvent) hence the infamous Forby's "Tung oil finish" which doesn't now, and never did, contain any tung oil. – Graphus Feb 04 '21 at 06:07
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If you want to show off the details of the wood, i would suggest skipping the shellac and putting poly right over the danish oil. Shellac is a sealer in the sense that it is very good as a base coat when there is risk that the underlying surface will bleed through the top coat (like knots in a pine board). That is why it gets used as a primer under interior paint when the surface needs to be sealed, like when cleaning up a house that was lived in by a heavy smoker (it's a good odor blocker, too).

For your purposes, poly over the danish oil will be just as durable without the extra shellac, and will look better too. Just give the oil plenty of time to dry, and remember to scuff the poly between coats. I have had really good luck with the wipe-on poly, and it's very easy to apply.

Z4-tier
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  • The shellac is deffo not needed here, but why do you say it'll look better without it? BTW scuffing, or otherwise abrading, between coats of poly (and all other oil-based varnishes) is not a requirement despite the widespread advice to do so. – Graphus Jan 23 '21 at 08:53
  • @Graphus scuffing between coats is listed in the instructions on every can of (poly)urethane I have ever used. Cured poly becomes impervious to the solvent carrier in subsequent coats because it cures to a hard finish by crosslinking polymerization and not just flashing of the solvent. Scuffing gives the hardened coat some tooth for the next one to grab onto and prevents delamination. For shellac and some other varnishes that cure only by evaporation, scuffing is not needed. – Z4-tier Jan 23 '21 at 14:42
  • "scuffing between coats is listed in the instructions on every can of (poly)urethane I have ever used" Yeah, and they're all wrong if they say it's necessary. It's the same with the vast majority of "conditioner" and other pre-stain products, their instructions are wholly incorrect on the best way to use them (as Bob Flexner has been attempting to inform them for years, and they've been turning a deaf ear). The advice to sand between coats of varnish (to be clear, not fresh over old) to ensure adhesion is as old as Methuselah, but it's not now and never has been needed for that purpose. – Graphus Jan 23 '21 at 17:17
  • [contd] I'm also a big fan of wipe-on, and almost always convert my varnishes to wiping varnish so that I can apply them that way. Do you scuff or lightly sand between coats of wipe-on, as thin as they are? I sure don't, and have never experienced any flaking or delams. – Graphus Jan 23 '21 at 17:19
  • I'll admit that I have skipped scuffing between coats of poly many, many times, and have never actually had any problems because of it. I'm not quite sold on it being totally unnecessary, since it's specifically included in the directions, and I don't know why they would include it if there is no benefit... but my own observations definitely support what you're saying. Maybe this is a case of "big poly" (like "big oil" or "big pharma") trying to steal our money. "First apply a coat of Rockler's specialty brand polyurethane.. then sand it all off and do it again..." – Z4-tier Jan 23 '21 at 19:07
  • The only purpose I see in scuff sanding is to knock down any dust that might have settled in the previous coat of finish or raised grain. – SaSSafraS1232 Jan 23 '21 at 23:09
  • thanks all! this is super helpful :) I'll do a couple test boards w/ the danish oil as a first coat (thinking just one?) w/ the poly over it and probably one w/ just the poly – markthethomas Jan 24 '21 at 02:50
  • @SaSSafraS1232, yes, but you can effectively remove dust nibs (unless they're particularly bad) just using the rough side of brown paper :-) – Graphus Jan 25 '21 at 11:12
  • "First apply a coat of Rockler's specialty brand polyurethane.. then sand it all off and do it again..." Oh, the cynicism! Likely correctly placed, but, Oy! :D – FreeMan Jan 25 '21 at 17:42