Watch this before using polyurethane wood finish!

there are a lot of great finishes out there but many people are intimidated by the whole finishing process so we've been making videos that help the average hobbyist woodworker get great results from common wood finishes these videos i think are the best out there because they cover a lot of important points that others just seem to skip over below this video i'll link to a playlist of our finishing videos that we've made so far just expand the video description or you can also find it pinned to the top of the comments section you really should check it out there is a lot to learn in there now today i want to talk about oil-based polyurethane because it's a very durable finish that's suited for both indoor and some outdoor projects it's not difficult to apply but i think my method will give you the best results so first you're going to prepare your surface by sanding really well we've made a comprehensive sanding tutorial that explains how to properly sand what grits to use raising the grain all that stuff you'll find that in the playlist below as well but for the sake of this video i'm going to suggest sanding to no higher than 150 180 if you plan to apply a wood stain or go to 220 240 if you plan to apply just polyurethane anything finer than 240 is a waste of time with this type of finish i also recommend hand sanding your final grit in this case i'm using 220 and going with the grain this will disguise the fine scratches that the sandpaper leaves behind now we're dealing today with oil based poly if you're applying this in enclosed space you really should wear a respirator with activated charcoal filters now if you can work in a well ventilated area that's up to you whether you want to wear a respirator but honestly if you're going to be working around any oil-based finish for more than just a few minutes it's probably a good idea to protect yourself unless you have excess brain cells to spare the application process for water-based poly is very similar to oil-based poly but we'll make a separate video about that down the road oil-based poly typically comes in three sheens gloss semi-gloss and satin all of them must be mixed thoroughly but semi-gloss and especially satin must not only be mixed well to start out it also must be mixed again between coats and perhaps periodically while you work if it's taking you more than a half hour or so to apply a single coat that's because satin and semi-gloss finishes contain flattening agents to reduce their naturally glossy sheen and you have to keep those flatteners suspended in the liquid or you're going to get an uneven finish so keep it mixed and notice i said mix it don't shake polyurethane you don't want a bunch of air bubbles in there so stir it well then stir it some more and stir it often i never like to use poly straight from the can you want to get rid of any crud or partially crystallized finish that may be in there so get yourself some disposable strainers you can find these wherever you bought your can of finish after it's mixed pour some through the strainer into a clean container and let it slowly run through that fine mesh this will help with air bubbles as well you don't have to strain the whole can just do what you think you're going to need for the coat you're about to apply now you have to decide if you're going to use the poly as it is or if you'll need to thin it any poly can be thinned water-based poly is thin with water oil-based poly is thinned with mineral spirits or other thinners whether too thin and how much to thin depends on a lot of factors and i don't want to complicate this more than i have to so simply put if you're going to brush it on you probably don't need to thin it right out of the can unless it's an old can that's kind of started to thicken up a little bit this is the consistency you're looking for if you do intend to brush it on if you're going to wipe on the poly with a cloth then you will need to thin it by as much as 50 and we'll get to that shortly so the question is should you brush it on or should you wipe it on honestly if you're new to this whole process i think you should probably wipe it on it's just easier to wipe on poly but since you have to thin the finish so much to wipe it on easily you do have to be more careful to avoid things like runs especially on vertical surfaces and you're going to have to apply more coats overall brushing on poly on the other hand involves a little bit more technique but it's worth learning to do i'm going to show you both in this video first we'll brush it on then we'll wipe it on of course to brush it on you need the right brush make sure that it's labeled for oil based finishes not for latex paint this usually means a natural bristle brush white china bristles come from hogs they're very absorbent so they hold the finish well and the solvents in the finish won't break this type of brush down as they will a synthetic brush so the bristles will remain straight and smooth i'm going to be working on a scrap of plywood just to demonstrate the process but i assume that you've sanded yours well and you've cleaned up all the dust i like to wipe mine with denatured alcohol but you could use a slightly water dampened cloth i'm also assuming you're working in a relatively dust free environment if it's the same place where you did your sanding you probably should let the dust settle for a couple hours then give your project its final wipe down and then you'll be ready to finish so dip your brush no more than halfway into the finish wipe off the excess and begin applying it spread it out well it's better to apply three or more thinner coats than two thick coats and as much as possible brush with the grain not across it it is very important to always work wet this means you shouldn't try to brush wet poly over a spot that's already begun to dry for example i like to work down the length of the surface in narrow sections but i must keep each section narrow enough or i must work fast enough so that my next stripe can overlap this first one before it has begun to dry i don't want to put new wet finish over sticky partially dry finish this could take a little bit of planning especially if you're working on a large surface like a table top but in most cases if you're working out of the sun in a relatively cool place you should have enough time to cover the whole surface before it begins to dry but keep an eye on it remember to brush with the grain as i work i like to go back over each section with long parallel strokes this will help to even everything out you don't want areas that are significantly thicker than other places you can see how uneven this looks when the light hits it but as long as the finish is still wet i can go back and even this out what i like to do is squeeze any excess finish from my brush so that it's all but dry then i go back over the surface using just the tip of the brush with long light parallel strokes that run the full length of the surface you can see how the dry brush evens out the finish with each overlapping stroke this works really well but as i said the poly must be good and wet to do this if it's a reasonably small surface like this one was you can go back and forth over this with that dry brushing technique after it's been fully covered and finished but if it's a really large surface you may have to do these dry smoothing strokes one section at a time as you work once everything's leveled leave it alone don't keep brushing because if it starts to get tacky continue brushing will make a mess of this coat even if you see a spot you missed if it started to dry leave it alone you can fix it on the next coat i like to clean my brush between coats so it doesn't get gummy a little mineral spirits or whatever synthetic brush cleaner you can get your hands on will do the job then put it back in the cardboard cover because that's going to help it keep its shape let this coat dry for at least a few hours overnight's best before you apply the second coat you're going to have to lightly sand this one and if it's not dry enough you're going to quickly gum up your sandpaper so give it time to dry before we sand let's talk about the wiping poly you can make your own wiping poly by simply adding mineral spirits or turpentine or another solvent that's compatible with an oil-based finish we have a video about solvents that you'll find in that playlist i've linked to below i like it pretty thin as you can see in this bottle this is a 50 polyurethane 50 percent mineral spirits mix i like to mix it in a sports drink bottle because the nozzle makes it easy to apply just make sure that you properly label the bottle if you're going to leave leftovers in there the wiping is done with a lint-free cotton cloth you can buy wiping cloths in packs in many home centers or online or you can just use an old piece of a t-shirt you don't need a large piece just enough to fold into a small pad like this applying the wipe on poly couldn't be easier just dump some on and spread it with the cloth because it's so thin it's going to spread very easily and it's going to soak in quickly some parts of the grain may really absorb more so if it looks a little dry in certain areas add more poly to it you can quickly spread in any direction but you should finish by wiping with the grain you're not going to have to level it out like you did the thicker poly which is what makes this method so easy however since so much of this poly has been diluted with solvent that's going to evaporate the coat will be much thinner you can see the difference here the regular poly is on the left the wipe on poly is on the right note how much thicker one coat is compared to the other a thinner coat is going to dry faster and you may be able to sand within just a few hours this could allow you to apply two or more coats with the wipe on poly in the same amount of time it takes to apply a single coat with a regular poly but it also is going to take twice as many coats of wipe on poly to build up the same protective finish that you'll get with one coat of the regular poly so there's a trade-off for the convenience there now when it comes time to sand which i'm going to show you on a different project use something around 400 grit sand very lightly you're not trying to take off finish you just want to level out the little bumps feel the surface with your hand as you work it should be perfectly smooth when you're done sanding if your sandpaper is gumming up you probably need to give that coat more time to dry when everything is smooth wipe off the sanding dust with a lightly dampened cloth water is just fine in this case then repeat the same process for a second and a third coat if you're brushing it on and perhaps a fourth fifth or sixth coat for wipe-on poly don't forget to lightly sand with 400 between coats after the final coat get yourself a brown paper bag like you get at grocery stores use this just as you did sandpaper to buff the surface as you carefully feel for any tiny bumps this will make it slick a snot and you'll have a finish you can be proud of now check this out we use blade guards and push sticks and safety glasses and hearing protection to keep us safe because we want to enjoy this craft for many years to come but what about our lungs i like trend stealth masks because they have silicone bodies that fully seal on my face this is important to me because a leaky mask is a useless mask the original stealth features a compact size easily adjustable dual straps for a proper fit on your face a downward facing exhale valve that won't fog your glasses and replaceable n100 filters the stealth light looks like an ordinary disposable mask but it features the same silicone seals an advanced head strap system and a downward facing exhale valve the 0.3 micron filter is replaceable as well i switched to trend stealth masks for my dusty work a couple years ago because they offer the advanced protection of a larger canister respirator in a less cumbersome size that's comfortable to wear all day long check them out at the link below the video

Channel: Stumpy Nubs

Views: 207,408

Keywords: woodworking, stumpy nubs, tips, workbench, table saw, scroll saw, drill press, quick tip, band saw, bandsaw, lumber, hack, hand plane, sharpening, tormek, worksharp, diamond stone, water stone, wood turning, bowls, lathe

Id: 7uoZSWof2DM

Length: 12min 21sec (741 seconds)

Published: Thu Jun 09 2022