How to treat an unfinished tabletop?
August 15, 2011 9:45 AM   Subscribe

How to finish this untreated pine tabletop?

I recently bought a VIKA FURUSKOG table top at IKEA to use as a desktop and somehow didn't realize it was untreated until I got it home. I was going to use it as is, but I found the untreated surface (particularly the edge) irritating to my arms when typing.

I know basically nothing about working with wood, what should I do to give it a better working surface? I've been told that once wood is treated with a polyurethane finisher it cannot be refinished, is that true? Should I care? It was only $40, after all. If I don't use polyurethane, would should I use as a sealant?

When I do decide to finish the tabletop, does it need to be sanded as most finishers instruct or has IKEA already done that?
posted by entropicamericana to Home & Garden (18 answers total) 5 users marked this as a favorite
If you use a polyurethane, you can always sand it off and refinish it later and that is what you should probably use. It will look good and be very durable.

Ikea has likely sanded the surface well enough for you to apply a finish. You'll high-quality paint-brush with either natural or nylon bristles depending on if you use a water or oil based polyurethane.

I just finished some shelves and got everything I needed at Sherwin-Williams. The people there were really helpful, really knew their stuff. They recommended this polyurethane and it was great. It looks awesome, didn't smell too much and was easy to apply.
posted by VTX at 9:59 AM on August 15, 2011

Hey, I recently bought the same table top! Well, and the rest of a table.

You don't really need to sand it pre-finishing, but it doesn't hurt. You're not trying to make a piece of furniture you're going to pass down to your grandchildren; like you said, it's a $40 table. Basically your choices are (1) do you want to stain it? and (2) how do you want to finish/seal it?

You've got a lot of choices there, and you can commit as much money and time to the problem as you want to. Let me tell you what I did:

(1) Wiped the table down with a wet cloth to remove dust. This is important. Also, seeing the table a little wet lets you know about what it's going to look like if you finish it without staining.

(2) Sanded it slightly with a medium grit paper; wiped the dust off again

(3) Decided I liked the color, and so wouldn't be staining it.

(4) Sprayed on a nice solid coat of spray polyurethane varnish (I used a semi-gloss). Let that coat dry. Over night if possible.

(5) Sanded with a lighter grit paper again to knock down the little spiky rough bits -- the varnish will actually help you see the parts that need to be sanded

(6) Sprayed on another coat of varnish. Let dry. I think I actually did one more coat to make it nice and hard, since I was using this as a rough-use desk and wanted a nice hard finish. You can put on as many coats as you want, as long as you let each coat dry in between. The more you put on, the more glossy and plasticy it will get.

Notes: if you don't let intermediate coats dry before applying another, you will get some wrinkling and weirdness. You don't want that. Also, remember that when you're spraying on the polyurethane, keep the can moving at all times! You don't want any unevenness in your coats. Brushing on your varnish applies thicker coats at once, and is more difficult to get even coats, so you probably will have to leave more drying time if you go that way.
posted by penduluum at 10:05 AM on August 15, 2011

If the untreated surface and edge are irritating you, definitely sand them. You probably don't need to do a lot of sanding on the surface, as they'll have done it, and can use a relatively fine grained sandpaper. Go with the grain of the wood in general, and you'll be fine.

You don't have to use poly, you can use something gentler and less stinky like tung oil. If you take your question to a local hardware store they can set you up with a little sandpaper and a finish that will suit you.
posted by ldthomps at 10:06 AM on August 15, 2011

If you like the color, you simply want to seal it. You have two basic choices: oil finish or film (varnish) finish. Oil will retain (and generally slightly add) to the sticky-ness of the surface. (And I don't mean sticky like sugar, I mean the surface will have some "grab" when you try to slide your hand or something across it.) Varnish will do the opposite, making the surface glossier and more slide-y. Oils are generally quite trivial to apply but don't add much protection: since they don't build a film, they don't supply additional hardness to the surface. Varnishes take slightly more to a lot more work (depending on what you do) but protect better. Oil/varnish blends are a nice compromise.

Once you seal the surface with an oil or varnish you cannot easily stain it (change the color). You can apply more sealant, though, but generally only the same type. (Not strictly true, but we're hitting the high points here.)

Arguing about wood finishes is like discussing religion, honestly, and with just as much mis-information out there. Seriously, about half of the finishing information I find on the Internet is just plain wrong (mis-classifying finishes, getting the chemistry wrong, etc.).

The simplest generic finish for most people to apply is either brushing on a water-based polyurethane or wiping on a "tung oil" from your home store (which isn't actually an oil finish, despite the name, but a varnish) from your local home store. The "tung oil" is generally a little stinkier but wiping on a finish is easy; the polyurethane smells less and brushing takes a little more work but will provide a thicker (more protective) finish in less time than applying N coats of wiping varnish.

Hit it with a light sanding of a reasonably fine grit (200, 220, etc.). Wipe off the dust, make sure you're in a dust-free environment (varnishes take a while to dry), and smack on some minwax polycrylic or "tung oil" varnish. Let cure overnight.
posted by introp at 10:12 AM on August 15, 2011 [1 favorite]

Oh, and if your first coat doesn't come out as smooth as you like (it depends a lot on the wood; the varnish might cause the grain to swell a bit, making the surface a little rough) just wait for it to cure; lightly sand it with your 220 grit again (to knock down the tiny grainy bits sticking up) and put on another coat.
posted by introp at 10:16 AM on August 15, 2011

I'm a big fan of wipe on oils or oil varnishes (Tried and True). Easy to apply, low or no VOC, foodsafe.

Not as durable as the plasticky poly finishes, but durable enough for most home uses.

I've got an unopened can of Behlen's Rockhard Table Top* finish out in the shop (waiting for the right project to try it out...). A brush is recommended, but lots of people cut it with Behlen's RHTT Reducer and wipe it on.

*Link includes a brief finishing primer.
posted by notyou at 10:38 AM on August 15, 2011

It all depends on what you want your finished product to look like. I've both done a blond finish (complete with poly) and a wash. Overall, the traditional finish was trickier and took much longer to complete, as it involved several rounds of sanding, staining, then finally putting a finish on. The results were great, though. For the wash, I picked out a paint color, mixed it about 50/50 with thinner, then used the mixture to paint my IKEA unfinished table (yes, I sanded first). The result is a table that's colored, but still shows the wood grain through the paint. It's a little more rustic, but it's a fun effect.
posted by Gilbert at 10:38 AM on August 15, 2011

Another option is Tung oil (as mentioned above) and Butcher's wax over that. It produces a very nice matte finish and is almost shockingly durable. I have a wooden stool I made about 20 years ago and finished once with tung oil and butcher's wax, and it hasn't needed anything since. Butcher's wax can be found at hardware or woodworking stores, and may also be known as Bowling Alley paste.

One warning with tung oil is that the rags you use to spread it can actually spontaneously combust when they dry. AFAIK it mainly happens in the presence of external heat, but something like a hot metal trash can in sunlight can do it. So read and pay attention to the directions on the can.
posted by rusty at 11:49 AM on August 15, 2011

Tung oil varnish doesn't spontaneously combust. (It's just cooked tung oil with some phenolic or alkyd resin in it.) That's linseed oil you're thinking of, whose oxidation is an exothermic reaction. Linseed oil is the oil that woodworkers used for varnish before the importation of tung oil from the far east in the late 1800s. Modern converted oils are less expensive and yellow less than tung oil but we cling to tung oil out of a sense of tradition.
posted by introp at 12:56 PM on August 15, 2011

Also, the link to the Rockler page on tabletop varnish is a great example of stuff you'll find on the Internet that's soooo close to being sensible but botches up some important details, confusing the issue. They imply that phenolic is the hardest varnish and that's why you should buy their stuff:
"Phenolic resin is more expensive, but makes for an exceptionally hard and durable varnish with excellent resistance to solvents and moisture."
But in fact polyurethane resin combined with alkyd (i.e., uralkyd) is the toughest of all available resins, by quite a lot. (See any of Flexner's books for a basic intro on the chemistry.) Phenolic resins are more flexible and somewhat clearer (less cloudy) but are noticably yellower. I wish pages like that one were correct and honest: "uralkyd from the local hardware store would give you a harder finish but your table finish might look a little hazy; this product is a great compromise between clarity and hardness." Someone will buy the stuff to put on their kids' play table and wonder why it scratches worse than the desk finished with Minwax.
posted by introp at 1:12 PM on August 15, 2011

Briwax was suggested to me in this thread.

Turned out great. Super simple to do.
posted by porpoise at 1:17 PM on August 15, 2011

I like oil based polyurethane finishes for anything that will be a working space. Oil finishes (Dainish, tung) are easy to apply (and reapply), but are least durable. Water based polyurethanes have come a long way, dry fast, and make the least stink. But they are still not as durable as oil based polyurethanes, which are my preferred type.

Typically, I thin the oil based polyurethane with turpentine for the first coat so that it soaks in well. I might use a brush for this first coat, and apply thin. Subsequent coats I might apply thinned, but using foam (or foam brush), careful to apply thin coats. The reason for thinning out the polyurethane is that it allows for fewer, easier to pop bubbles, and relatively quick drying. Tabletop/work surfaces will get several coats, with light sanding in between. If you want a durable surface, don't skimp on the number of coats. Also, if a coat is well dried, the light sanding helps the next coat bond. Sanding dust can be mopped up with a clean cloth of paper towel dampened with thinner/turpentine. After the second or third coat, the sanding shouldn't be too vigorous, just enough to matte the finish and create something for the next coat to stick to. Non work surfaces need fewer coats, maybe only a couple quick thin ones unless you want to go all out. It might sound like a lot of effort, but on a warm dry day, any reasonable piece of furniture can be done easily.
posted by 2N2222 at 1:19 PM on August 15, 2011

introp: I was thinking of boiled tung oil, not tung-based varnish. Tung oil and linseed oil both dry exothermically, and both can combust oil-soaked rags. It's possible that boiled tung isn't used much anymore -- it's been a while since I did any wod finishing.
posted by rusty at 6:36 AM on August 16, 2011

Response by poster: Follow-up, if anybody is still out there: If you're doing this in a townhouse without a garage or woodshop, what product would you recommend?
posted by entropicamericana at 3:08 PM on August 22, 2011

Doing it indoors?

Pure linseed or tung oil such as the Tried and True I linked above. I periodically buff out cup rings and shallow scratches on my dining table and re-apply a coat of Tried and True Varnish Oil without the table leaving the room.

That's one of the benefits of a low VOC, foodsafe product...
posted by notyou at 10:09 AM on August 23, 2011

Response by poster: Would boiled tung oil be okay?
posted by entropicamericana at 10:11 AM on August 23, 2011

"Boiled" traditionally meant just that -- pure cooked oil that would dry faster than straight oil. For some manufacturers that's still what it means. For others, "Boiled" means chemical "driers" have been added to the product. When the label warns you about noxious fumes, those dirers are the reason.

If your boiled tung oil is a true polymerized (cooked) tung oil, there is no risk. If it isn't, there may be. Read the label, or better, visit the manufacturer's website and see if you can find the product's Material Safety Data Sheet. Here's an MSDS for Pure Tung Oil.

Here's one for Minwax Tung Oil Finish[PDF].
posted by notyou at 10:43 AM on August 23, 2011

Response by poster: Well, I decided at this point I'm not into investing the time and effort into doing this properly, so I'm getting rid of the tabletop. I will probably be looking into using tung oil on some future projects down the road, but everything I've read indicates it probably isn't what I'm looking for in a tabletop. Thanks for the answers!
posted by entropicamericana at 3:04 PM on August 29, 2011

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