perhaps the most confusing set of questions most beginners have when they decide to adopt the woodworking obsession (or craft if you prefer) is about what to do with the wood when the project is ready from a physical perspective to make it look its best and protect it from its environment. of course, trees aren’t temporary objects and they’re already going to stick around a while even if they’re dead, cut up and joined together. but we can’t leave well-enough alone and have to start pouring, spreading, spraying and drying stuff on them to make things look special. and there’s nothing wrong with that. but let’s talk about finishing. this isn’t an article about planing, scraping and sanding (though if you’re interested i can cover it at some point in the near future). this is about what happens when the project is ready to go and just needs the final touch.
finish really comes down to four possible options — natural wood, heat treatment, a finish that penetrates and stays in the wood and a finish that sits on the wood like a film. natural wood is obvious. you polish it and it’s done. heat treatment includes things like high-speed burnishing (common for things turned on lathes) and yakisugi (which goes by various names but is a traditional japanese, korean and chinese technique for making wood resistant by converting its outer layer to charcoal with a flame). penetrating finishes are usually oils, the most commonly-used being boiled linseed. film finishes are things like polyurethane and varnish. of course, there are paints, dyes, stains and other things that can be put on wood, too. and we will look at those but only at a very surface level (unintended pun) and there are many techniques to make those work and more varieties of paint and dye than i could possibly cover in an introduction, even just to that particular type of product.
so you have your piece joined together and you’ve sanded it to a high grit (if you’re not sanding to a high grit, you’re honestly not worried enough about how your piece looks to care what kind of finish is on it, as far as i’m concerned — don’t skimp on the preparation. if you’ve spent a week or two building a beautiful piece of furniture, take a few hours and go through all the sanding grits and get the thing to at least 320 but i take mine to 400 or higher without exception and the extra time truly shows in the smoothness of the surface and you can see that across a room). you’re ready to get out the brush, pad, sprayer or whatever and let your creativity shine (by reflection). but you don’t know where to start.
natural wood
this sounds like the easiest way to finish wood but it’s not quite that simple. sure, if you’re building something that looks like it belongs in an antiquated log cabin, indistinguishable from the firewood pile, that’s probably true. but if it’s a piece of fine furniture, there are a few considerations. one is that wood is not actually very durable without a protective finish. it will get rough and damaged with use. this depends on the species, of course — pine will hold up pretty badly but hard maple or live oak will survive your toddler’s most ardent attempts at creative destruction for years. relatively speaking, that is. but you can assume that an unfinished piece is an unprotected piece.
there are some reasons you might want to leave a piece unfinished, though. one is tradition. there are some styles that simply didn’t get finished historically. roman, etruscan and ancient-greek-era woodworking was (mostly) unfinished. it was thoroughly polished but didn’t have any sort of coating put on it. given the lifestyle of much of the aristocracy, though, it was probably thoroughly soaked in wine by the time the years had passed and grape oil isn’t that bad a finish when you think about it. not that i’d suggest pouring your fine merlot over your nice new cabinet-on-stand. but despite the color transfer it’s an interesting way to get the wood to shine. some chinese, japanese, korean, vietnamese and mongolian traditional styles were never finished and, if you’re looking for historical accuracy, you probably won’t finish them, either. workbenches, too, are usually not finished but that’s for a whole other reason. why finish a workbench that’s going to get coated in finish and scraped, scratched, dented and cut into every day?
the important part about unfinished wood, though, on a piece is that it’s intentionally unfinished. it’s not that you started the project and just got tired before you really got it done. you made a conscious decision that the piece is better left without the coating. perhaps it’s because it’s going to come in contact with hot dishes and those will destroy the finish completely. perhaps it’s because it’s going to get wet all the time and no finish could survive. maybe it’ll be near a fire and flammable finishes are unwise because you like your house in its unburned state. maybe it’s tradition. or maybe it’s a utilitarian piece that’s never going to be seen outside your shop and you don’t care — though there’s a great argument for finishing shop furniture beyond prolonging its life and it’s simply that there’s so must dust in a woodshop and you don’t want it to stick to the fixtures and fittings so giving them a quick few coats of shellac means they’re so much less likely to become dust traps. if you’re going to leave something unfinished, though, other than perhaps your workbench, my recommendation is to treat the sanding process like the final prom dance — go big or go home. sand to higher grits than you think is necessary. think 600 or 800, maybe even higher. people are going to be touching this surface with their fingers and theirs might not be rough from decades of sawing and chiseling. you want your piece to give them tactile joy. so spend a day at the linguistically-complex beach and bask in the joy of sand.
heat treatment
while there are some boards available already treated, heat-treatment as a finish is relatively uncommon. when you hear this phrase, you may be thinking of something like thermally-modified ash, which has become (for no particular reason i can come up with) popular of late — it’s awful to work with and extremely dangerous to breathe the dust of so please take precautions if you’re going to investigate it. but there are really two common heat-treatment strategies for finishing. one requires thorough preparation. the other requires none at all but a decided pyromanic streak that appears to be centered on the home islands, though it’s spread throughout asia for centuries and into the west in recent years.
burnishing is the act of rubbing something hard and fast enough to make it smooth by the application of friction (heat and pressure) to soften the outside layer then harden it to the touch. i know that sounds complex but it’s really not. imagine you took a knife and rubbed it gentle across a piece of wood. now think of doing that faster and faster, thousands of times. what will happen? the wood will get smoother and smoother as it gets hotter and, when it cools down, it will be like touching hard glass. this same principle applies to many approaches to finishing without a liquid/sprayed finishing product. there are two places this is common — large surfaces and round things. for something like a table, you use a burnishing wheel on a buffer (or you can do it by hand but you’d have to be a masochist to try this because it will take literal hours of high-speed rubbing). imagine you’re polishing the wax finish on a car and just go over the tabletop with the high-speed spinning surface. it will polish the thing smooth and the more you use it the smoother and more glassy it will appear. nobody will believe you it doesn’t have a coating on it. but you have to prepare that surface — sand to at least 400 but i’d go to 800 or even 1200 before even thinking about turning on the polisher. to go from a 220 surface to fully-polished glass-texture will take bloody ages. to go from 800 to mirror will be a tiny fraction of that time and you won’t wear out either your patience or your polisher. turned things are often burnished but you don’t need to apply a powered polisher because the piece is already moving at high speed. many turners just use fine wood shavings or a burnishing tool or cloth held against the finished piece. you’ll know when it’s done because it won’t just shine like glass. it’ll stop feeling like wood and start feeling like ceramic in your hand. if it still feels a little rough, you’re not finished. keep going. and you want it to get quite hot — don’t burn your fingers but it should feel like sitting a little close to a fire on a cold night.
yakisugi (literally fire + cypress) is a traditional japanese technique for preserving wood for outdoor use. and, as the name suggests, it was generally done on cypress. in the west, cypress is rare and, even in japan, it’s not that common anymore. but the technique will work on almost any wood. i don’t recommend you do it on white pine but you’re welcome to experiment on anything you like. it’s quite simple. you get the piece ready in its unsanded state, torch the outside to somewhere between lightly-charred and full-on-charcoal, depending on the look and protection level you’re going for, then you brush off the dust. some people like to seal the outside with a polyurethane or varnish while others leave it in this state. both are fine. i like to brush it with a spinning wire-wheel to get off all the excess dust then spray-lacquer or spray-shellac the outside for protection. i’ve seen successful epoxy film finishes applied over yakisugi that are quite beautiful and extremely protective. this was a relatively simple way to avoid wood becoming rotten — if it’s charcoal, bugs and bacteria have nothing to eat so they ignore the wood and it’s now realistically become a stone. in case it’s not obvious, by the way, this will turn the wood gray or black. it’s not just protective. it’s decorative. if it’s not dark enough, you can dye the finished product with ink or stain and i’ve had good luck with light treatment plus ink for a truly black result even on the lightest of woods (in my case, beech and maple, though i’ve seen it done on basswood and it looks fine, though if you’re using basswood for an outdoor construction project there are other things you may be neglecting — like the fact that basswood is so light you need so much of it for any significant strength you might start thinking your furniture was made from lego bricks…).
penetrating finishes
the most common finishes for wood throughout the past few centuries in the west are oils. boiled linseed oil is a particular favorite of the modern woodworking community. there’s not much to this one. there is a huge amount of complexity in the chemistry of these products but their use is simple. once your piece has its surface prepared, pour on the oil and let it soak in. when it’s soaked in and you’ve put enough coats of oil on it, wipe off the surface to eliminate excess oil and you’re done. the wood is just drinking it in until it can’t absorb any more and the finishing process then continues until the oil has cured (set, hardened, polymerized, whatever — you can use these words interchangeably, though they don’t quite mean the same thing, as all these processes should apply). raw linseed oil is another option, though it will take many times longer to be ready for use. you can realistically use any oil you like and they have various properties. tung is great. mineral oil is a bit problematic because it doesn’t really ever fully cure so it can be washed out very easily and that’s not exactly protective. vegetable oils can (but don’t always) have the potential to go bad even after they’ve dried because of the moisture in the air and i would strongly caution against using them on furniture unless it’s very temporary — don’t think your kitchen is the source of your furniture finish unless you want a disaster to clean up later. if you want a finish that is close to the wood, just get some boiled linseed oil and go to town. different brands have different chemical combinations — i think the nicest is actually the tried and true but watco makes a nice one and the options are endless. try some and see what you like. some people advocate making boiled linseed oil and that’s always an option but it’s a lot of work and can be extremely dangerous so if you start walking down that path make sure you’ve got good insurance and read a few books about chemistry before you begin. i don’t make my own oil finishes and there’s a reason. if that’s something you enjoy, though, go to town and have fun. but don’t say i didn’t warn you if you end up with singed eyebrows and a kitchen in flames. because you very well might.
film finishes
when it comes down to it, most modern finishes fit in this category. before i start, though, what might be useful to know is that many people do an oil finish then either coat in wax (a type of film) that is rubbed on the piece after the oil has finished curing (sometimes before it’s completely cured, though i would recommend patience to avoid white streaks resulting from cross-contamination and temperature interaction). that’s probably the simplest film finish.
other things that can build up a film on the piece include shellac (my favorite), lacquer (my other commonly-used finish), varnish (which takes an age and a half to do well but looks great on a boat), epoxy (encase the thing in plastic and it’ll last nearly forever) and paint (i know — you’re a fine woodworker and you want to see the wood but hear me out and it’s totally traditional).
shellac is awesome. it’s all the awesomes at once, actually. but you don’t have to take my word for it (though you should) — try it for yourself. it’s fast (unless you put on a very, very heavy coat and just don’t do that to yourself) to apply, to dry and to polish. you can wipe on a coat and by the time you’re finished all your parts you can go back and apply the next coat because it’s already dry. you can have a whole piece finished in an hour or two and it’s ready to use the same day. shellac is a natural product so it’s perfectly safe for children and food and whatever — it’s a … residue from a certain insect and you can feel free to do the research if you’re curious about more because i’m not a biochemist and i really don’t care that much. the bug is called a lac and it’s native to the indian subcontinent — like many good things, it’s only made by the females, by the way. anyway, it usually comes in dry flakes or premixed and you should use an extremely light preparation of it (diluted in alcohol). the best part about shellac is that you can apply it with a cloth — no complex tools necessary. doesn’t need to be sprayed or rolled or anything, though you can if you really want to. shellac really is the simple and durable finish you’re probably looking for. by the way, lightly sand between the coats with 400 or higher and you’ll get a much better finish but you don’t have to clean between sandings because shellac is a merging finish — the solvent (alcohol) reactivates the existing shellac so it dissolves and you won’t see the sanded particles between the layers. imagine it’s like salt being dissolved in water so it realistically disappears visually.
unless you want lacquer. it’s protective, hard, glassy, smooth and far, far more involved as an application system. the result rewards the patience and effort, though. again, light coats are best and it’s far better to spray. if you’re going to use a cloth or brush, just do shellac. lacquer that’s brushed on is going to streak and you’ll spend the rest of your natural life trying to polish those marks out. it’s not worth it. spray light coats and sand between them (don’t forget to brush the sanding dust away or you’ll just trap the dust between the layers and end up having to start again after sanding the finish off to fix the problem — don’t ask me how i know that). you’ll probably need a place to spray but even the prepared spray solutions will give great results so you don’t have to invest in a complex spraying system to do small pieces and see if you like the way lacquer treats you. if you do a lot of it, the rattle-can versions get very expensive and you’ll want to get an inexpensive hvlp (high-volume-low-pressure) spray system. this works for other finishes but please don’t try to use it for paint because the results are suboptimal and you’ll kick yourself. more on that in another article, though.
varnish is the old solution — i won’t go into how it’s made but you can think of it as a protective film that’s made by mixing oil and a resin then layering it on the wood. you should, like with lacquer, lightly sand between coats and thoroughly clean the dust away. varnish isn’t self-meshing like shellac and you’ll see the dust. it’s usually very durable. if you’re making outdoor furniture and you want it to look glossy and smooth for years, this is your answer. marine varnish in particular is highly-protective against sun and the elements. there are various brands out there at different quality levels. totalboat makes some really nice stuff and that might be a good place to start. i haven’t recommended specific shellac and lacquer because whatever you get at your local woodworking supplier will be ok. varnish varies more — some is truly awful and hardens then cracks so do some research and ask your friends what they use. totalboat marine varnish is excellent quality but a little pricy. you do, however, get what you pay for. you can theoretically spray varnish but i wouldn’t bother. brush it on and sand between coats until you’ve built up enough layers for the level of protection you’re looking for.
with all these finishes, by the way, if you want a less glossy surface, you can just use steel-wool or a rough paper bag after your last coat to take down the shine and make it more mat. i think that satin look and feel is preferable but i’m not into the plastic look.
speaking of plastic looks, if you’ve spent much time in bars, you know there’s another film finish we haven’t covered yet and i hesitate to even mention it because it looks awful and is a massive pain in the ass to do — an even bigger one to redo if it gets damaged. and it’s expensive af but some people use it and it’s necessary for specific situations. like bars — you know, those places we used to meet dates before the world went crazy and hugging your friends in public became an act of domestic terrorism? those things are meant to get coated not just in liquid but alcohol — if you remember a few minutes ago i mentioned alcohol being a solvent that dissolves shellac? yeah. don’t finish a bartop in shellac because the first time someone spills their manhattan your finish is … finished. coating the surface in epoxy (also known as resin, composite plastic and various other things) means it is protected. most of this is petroleum-based and nothing is going to get through it but sheer physical trauma or heat. that’s great. except it looks like the wood just got encased more thoroughly than han solo in a mining colony. if that’s your aesthetic (or you run a bar), that might be your solution. if not, just carry on walking. again, i recommend the totalboat stuff but there are lots of good epoxies out there and you can take your pick. thin layers, though. put on a really thick layer and you won’t just have plastic. you’ll cook the thing and might even start a fire. epoxy is thermally reactive. a word to the wise — if you pour too much, it’ll be the fourth of july in your workshop and there’s no way to stop that reaction unless you want to dunk your workpiece in a bath. if your workpiece is a full-sized piece of furniture, this can be a disaster.
there’s one other film finish we haven’t mentioned yet. if you’ve watched a lot of woodworking in the land of youtube, this will be obvious. poly. polyurethane is what happens when you take a carrier (usually linseed oil, actually, though other things are used — even water-based carriers in some cases now) and add multiple plastic resins (urethanes + poly, the prefix for multiple — so polyurethane) you get polyurethane finishes. they work the same way as varnish but they are extremely protective. some people like how they look (i do) while others don’t (who usually say they don’t make the wood look as rich, which they don’t, though i like my wood to look more raw and natural). poly is fast to apply and relatively simple. it can be brushed or wiped or sprayed and it’s easy to do. why do i use shellac and lacquer if this is both easy and far more popular in the community? two reasons. shellac is really cheap and poly isn’t. but that has nowhere near the level of decision-making power as the fact that poly takes hours, sometimes days, to dry, depending on the situation and workpiece and environment. and shellac is ready almost-now. they look very similar and feel so close most people (including me) usually can’t tell the difference. one other thing. shellac is natural and smells pretty nice. polyurethane is a petroleum-based (usually) multipart plastic and smells like a chemical plant. that may not bother you. but it’s something to be aware of.
hybrids
just a short note. you can mix varnish and oil. you can mix poly and oil. you can mix oil and oil and other oil. don’t mix oil and water — there’s an old saying about that and, despite the fact that almost all folk wisdom is slightly less wise than pissing into the wind, this one is true. you can mix poly and oil or even shellac and other finishes. there are various formulas but the obvious one is half-and-half linseed oil and either varnish or poly. many people swear by this combination. i like shellac and lacquer and i don’t generally swear much. finish is very personal and the result is something you should have tested multiple times on scrap before you even consider using it. but these hybrids are often sold as things like “danish oil” or “combination varnish” — there’s nothing wrong with these products. just be aware of what’s in them before you use them and all will be right in your world.
colorful things
other ways to finish (or coat before finishing) wood include dyes, stains and paints. my favorite dye is sumi ink. you can turn wood gray or black just by mixing the ink and painting it on. you can mix this with shellac or oil and allow it to dye while you do the first few coats of finish. it’s a beautiful technique and the result can be spectacular. if you get the mixture wrong, the result can be an uneven mess. do it on a test piece first. several times. when you’ve mastered it, go for it. don’t say i didn’t warn you. it’s messy. and wear gloves. sumi ink is permanent and i don’t care what color your hands started out — they’re not naturally this dark. you’ll look like you just had a date with a coal mine if you don’t wear protection when touching it and it’s not going away any time soon. we use it for calligraphy and some of that has lasted millennia without fading.
there are various type of stain (usually thought of generally as gel and liquid) and they work much like dye. they soak into the wood and change its color. they’re mostly various types of pseudo-brown and reddish tones. they do what it says on the box. not very exciting but if you want to change the color they’ll work. but if you stain it that’s not your protective finish. apply shellac or poly or varnish or lacquer on top or you’ll probably end up wondering why the wood feels so rough after a year or two.
paint is a whole discipline in itself. i like milk paint (which can be made without harming any bovines, something that’s very important to me, by using synthetic components and water). like stain, this isn’t protective. it’s just for the color. and the best part for us as wood-lovers is you can see the grain through it. so it’s got the beauty of wood but in any color you want. it’s (somewhat) traditional, too, even in really bright colors — you should see some of the research at hancock shaker village about what colors they actually used and it’ll blow your mind if you think the shakers were boring and bland, i promise you! more modern paint technology includes things like latex or water-based paints. these can be protective like a final coat or you can (be careful if you assume without checking your particular paint and finish) use another coat over them — usually poly works fine over most paints but i would be very careful doing it without trying it first and checking to see if there’s already a coating in the paint. if it was me, i wouldn’t use something meant to paint the inside of a house on a piece of furniture. builtins, definitely. but if i’m going to do that, i’ll spray it. and there’s my last piece of painting advice — if you’re going to milk paint, use a brush but, if you’re going to use interior paint, spray it. and ask around about the kind of paint you’re thinking of using to see what people have good results with. you’ll need to thin the paint considerably with water but, more importantly, much modern paint doesn’t like hvlp so you may need a more involved spraying system. getting into serious professional-level cabinet painting isn’t a cheap rabbithole to dive into. but going halfway is just going to disappoint you with the results so carefully consider this before you go beyond milk paint on that road. i avoid it almost as much as handshakes.
final thoughts
after nearly five-thousand words on the topic, we’ve now finished. that was hopefully helpful but if you have any questions you know where i am. find me on one of the forums or send me a message and i’ll do my best to answer anything i can. i’m not an expert finisher but i can try to get you in contact with one if you have a really technical question. i’ve said it a few times already but this is a very important point, by the way, before i end. when you’re finishing, more than any other step in the building process, testing your process on sample boards is vital. if you don’t test, you’ll end up crying because the result is unpredictable. a new species, new preparation method, new finish, any change at all — even a new temperature or humidity level — can have a dramatic impact on the result. better safe than sorry applies more than you can possibly imagine unless you’ve been doing this a while and experienced all the disasters that show up when finishing. if you think glueups are stressful (i don’t), you haven’t had a real finishing nightmare yet. so be careful but have fun and experiment until you find something you like.
spoiler alert, though, it’s probably going to be shellac. i don’t think i’ve ever known anyone who didn’t just love the stuff. ok, one person. but he admits he’s got a crazy love for boiled linseed oil and doesn’t make furniture for sale, anyway. so time isn’t an issue and time really is the key. plus, shellac doesn’t mean you can’t use the magical oil to change the wood’s tone first. i just like the look of shellac on wood more than penetrating oils. that’s all for this time. happy finishing!