Thanks KZfaq for showing me a mad lad that build a floor just to prove a point.

Hello, sandpaper manufacturer here. I can say that yes you need at least 15 degrees to offset the waves, this is also something that takes place all across sanding in general (not just floors). The screen we make for hand sanding and pole sanding in drywall is actually die cut at 15 degrees to avoid waves.

Howdy from the States! Glad you're still making videos. I had never sanded, stained or finished a floor in my life. Bought a house over the summer and ripped the carpet out to find wooden floors. I followed most of your videos to a T. Took me about a week and wasn't easy. Had other contractors come in for varying work asking me who did my floors after it was all said and done. Got a bunch of compliments etc stating it looked like a professional job. Wanted to thank you man. I'm incredibly grateful for these videos and I'm glad I happened upon them. Along the way I got a ton of different and contradictory advice. I don't know why but I went with yours. It's amazing how hard it is to find the 'right' advice. Anyways thanks a million.

It took me 25 years as a Wood Flooring Contractor to figure this out on my own. You explained the science of wood grain and drum sanding perfectly. I wish I had had access to this video 24 years ago, which would have eliminated some callbacks to "fix the ripples!"

I started my own floor sanding business 4 years ago after working under my dad. Unfortunately he passed away when I was too young and didn't get a chance to fully learn. I have learned more from your videos and program than anywhere else, and for that I am forever grateful.

Great explanation. Sanded my upstairs over the summer and I couldn't explain what I was seeing after I finished it. Everyone said I was being too picky. Now I know how to fix it! Some of the best sanding analysis online. Beyond professional and skirting into scientific understanding of sanding as a trade. PS - the demonstration with the markers was a great way to explain why to diagonal.

That's how I was trained to sand a floor so it's good to see someone putting the record straight, and the reasons why. Good job

As far as I am aware you are the only person showing how to sand floors correctly. Also how to fill holes and gaps between boards. Many Thanks.

Cross checking a hardwood floor. I’ve worked in auto body and paint for 20 years and I cross everything from grinding metal to flat blocking clear at finish but probably wouldn’t have thought to do this. I’m doing my first hardwood floor this weekend and was dreading it until I saw this video. Now I can’t wait to fix and finish! One of more satisfying videos I’ve watched. Thank you!!

I do the exact things when planning old work tables, so this makes perfect sense to me. I never thought about it on floors. I did a few 45 deg passes on the 2 floors that I refinished and never thought about it. Great video.

Happy to learn that my dad taught me correctly, and especially glad that I just followed what he taught me when I sanded my own floors.

I used to do scientific samples preparation for a laboratory for electron microscopes. We always alternated sanding directions until all of the previous directions marks were gone. Worked great for high precision work, makes sense to do it for floors. Thanks!

I used to do this professionally and am about 10yrs out of practice. I am in the process of renovating my own house and have been trying to explain things to my father.... this video has been invaluable for putting into words the things I mostly remember but am very out of practice at. The WHY of things is important. Cheers mate, thanks for the clear and concise explanation.

A bit late on the comment here, but I am glad I found your page, I have a house built in the 50’s that has original red oak floors that has been trashed by years of stains from spills on a carpet. I’ll be tackling and refinishing my wood floors. Thank you for sharing all the knowledge.

Very good explanation and demonstration. 👍 With a typical 3 cut sanding I cross cut to the right, then left and then straight for the final sanding. I've tried explaining this to my boss and coworkers, just to get cut off with the same arguments about scratch and track marks. Keep it up!

I was taught to sand 15-30 degrees to the grain with the drum sander. I find it varies depending on the floor sometimes you gotta hit it at 45 degrees from multiple directions sometimes 5 degrees is fine. There are so many variables I don't even know how to type a comment about it, and this video made me aware of even more variables, very informative and well presented.

Best explanation ever about the proper technique for using a drum sander to refinish a hardwood floor. You saved me from making a mess of things, thanks very much!!

It's great that we can share real experience like this to figure things out. Thanks... I've met lots of people with 30 years experience doing a job, wrong... And they rest their laurels on time instead of quality. The bad habits you learn when you start almost always carry on forever and get worse over time. Experimenting helps us learn when we see different results. It makes it easier to figure out what was actually happening. So kudos to you for this one.

I purchased your "How to sand a floor" training videos back in 2019 and really learned a lot! I'm in the process of installing some random width white oak flooring in our upstairs master bedroom and I'm very confident with that part.(I have installed hardwood flooring two previous times. But, I have never sanded and finished a hardwood floor yet! This current video came along just in time as I'm going to be sanding and finishing after the xmas holiday. Thanks again for your training videos and your youtube videos! Paul from Michigan, USA

As in most fields of endeavor, the prevailing 'correct' way is seldom challenged...though its results may be less than satisfactory. Good video. I have sanded and refinished my share of floors as a renter/owner. I will remember this video should the need arise again. Thanks. Subscribed.

Love the explanation. I have watched enough of your videos to know that you have to go diagonal for the first pass! And now I know much better why!

Excellent explanation and exactly right! I've sanded wood floors for 40 years. I always cross cut my first cut. Newly installed wood floors are especially important to do this due to the amount of overwood across the floor. I've never had problems with ripples

Great video!! The stain really brought out the ripples when you did the diagonal cut

Thank You for Yours videos ! Thanks to you, I have refreshed a perfectly oak floor in my home 👍👍👍

Excellent. A professional who discerns and cares. Good for you!

I just tore my carpet out of my first home I bought I knew there were hardwood floors since it was built in 1909 ! Someone painted them with house paint white for some reason I have no idea why but they seem in ok shape and I was looking for videos on sanding them found your video on people teaching the wrong way on KZfaq! Bright me to this and I’m grateful for your videos since I don’t pay anyone to do work on anything I learn it myself and do it ! These videos are what I needed to find! Can’t wait to sand them in the spring ❤

Your technic makes all the sense necessary to fix the problem , thanks for sharing brother.

Interesting indeed, I refinished and finished new floors many times without flaw but then again when I broke out that style sander it was only to remove pre-existing finish or level new boards and I made light passes to help mitigate any issues. Afterwards we relied on a few grit levels of sanding attachments for the buffer to do the real sanding to prep for finish like you do around the edges with edge/rotary sanders.

I am going to do DIY project next week and follow your steps. And will share the result. Thanks for sharing the videos, very informative for beginners like me 🙏

I'm currently ripping up carpet and tiles in my house and found really nice hardwood flooring underneath, just needs a good freshen up, so I've been watching a bit on KZfaq about repairing, sanding and refinishing old hardwood tongue and groove flooring. I'm a qualified automotive refinisher (spray painter) and was constantly wondering why people are sanding everything straight?? Then I see your video cross hatching it, exactly the way my brain would think to do it from my experience in getting car panels dead straight, so I'm glad to see that cross hatch sanding will work fine on the floor, and I'm not a complete madman for thinking to do it this way!!

Almost always rough cut between 30-45 degrees. And then gradually bring it straight with consecutive cuts. Has always worked well here in new England where the floors are almost always trashed to start and you have to cut out more than wood density differences. Nice explanation!

EXCELLENT tip and a PERFECT demonstration. Thank you!

Been crosscutting for surfaces caused by this density and relevel problem only on a much larger scale All your explanations how waves are caused and cured are true I have had to repair these problems as my work required for over 45 years I agree with what you say and proved it many times

You are the man! Thank you for sharing all of your tried and true techniques.

Thank you for this. About to DIY a floor. So glad I found this video. Watching all your content 😊

Absolutely! I always sand my first cuts (multi cuts because I sand gymnasiums so lots of poly to contend with) at about a 10-20° angle and then straighten up on my follow-up cuts. Just have to be sure to get any angle scratches back up first!

You definitely saved my floor boards, my time, machine hire and materials. Your a good man, thank you. 🙏💪👊👍

I can’t get over the fact that you built a floor to make this video. That is some serious dedication.

Great video! I'm about to start my first refinishing project on our entirely jarrah floored home in Aus and this, and your video course is an excellent training ground. Thanks.

This is an excellent explanation and demonstration KZfaq, we love it and thank you very much!!!❤❤❤👌👌👌

Awesome info. My dad sanded his 100 year old floors back in 1979 and he sanded twice on a diagonal. No ripples

I've been refinishing floors and stairs for 25 years. You're absolutely right.

Amazing results. Funny how the right method always seems obvious in hindsight, and yet some so-called "professionals" insist on doing it wrong.

Helps a lot to take ur time with the trio between drum sandings as well. I’ve known some folks who don’t even use a trio or anything and they’ll have that ripple effect when all is said done

I'm still repairing holes and pulling nails and staples on some hardwood at my house. It's seen a lot of damage, so I'll be going for a rustic/battered look. I'll try a couple test spots, but I'm thinking about using a black filler on the cracks and repairs. If the floor doesn't turn out, I'll probably cover it with ply and laminate, but fingers crossed. I'm feeling more and more prepared though after watching these videos. Thanks for taking the time to make them, and I wish you continued success.

This is such an accurate point in this video. It's exceptional, the level of analysis and explanation you gives. I think so many folks are already a bit nervous when redoing their floor, and since there are so many folks who continue to say you should go with the grain always, that DIYers are just a little too hesitant to deviate from that "advice." I just did my floors. I think they look great because I did some research and paid crazy attention to detail since I've never done this before. Although, I saw this video after my first couple cuts, and in a really tight spot between the island and oven/fridge, I have some minor flaws that this technique would have eliminated. Awesome videos though! And definitely helped. Three other flaws... a damn mosquito got in the poly (my kids say in a few million years, they'll extract the DNA to recreate some animals that exist today). Also, while staining, I put my sweaty arm down over a towel, but the sweat went thru the towel and into the wood. I didn't notice and even though it dried, the stain became a little darker where my arm was. I totally didn't expect that. It's not noticeable unless I point it out, but it's a thing. And a few drops of water (or beer) from the sink got on the floor and resulted in a few dark drop-sized spots. I can live with that and it's covered by a rug.

Brilliant video. Makes sense. This is also the reason why car gearbox’s have helically cut gears (diagonally cut) to eliminate noise and vibration.

damnn i usually only ever sanded at a 45 if the floor was super uneven to begin with, this actually helped a lot cause i would notice the ripples(clients never complained or see them) but i do and it always bothered me, i want to do the jobs as best i can. Thanks for the thorough explanation it made a lot of sense.

I sanded floors for twenty years ... I always did a 45 cut. Usually on the first grit to cut the floor level. I hadn't considered doing it on the second cut. Very interesting... I must have a go . Excellent video BTW 🙂

For 9 years full time (and 4 years part time) I worked with my brother installing and refinishing hardwood floors. He did all the big machine sanding and I did all the edging, scraping, vibrating, etc. I noticed a few things in your video that did not look quite right at the 5:02 mark and the 11:45 mark. My brother has been installing and refinishing floors since 1985 so I sent the video to him. He said: The small waves (chatters) every 2" or so visible in the reflection in the middle of video at the 5:02 mark is from an out of balance/worn drum or loose belt. Probably the drum. If they are exactly uniform in spacing then it is an out of round rear wheel. The waves 1' apart you see at the 11:45 mark are from you walking too slow with the drum pressure set to max on your initial sanding. Everything else in your video he agreed with. BTW, he has been doing his initial sandings with 36 or 40 grit at a diagonal then 60 & 120 with the grain like you recommend since at least 1989 when I first started with him. He then uses 120 sandpaper on a buffer to remove any minor chatters that may have occurred and to remove lap lines. I've seen the diagonal system you use work on everything from: a 4000+ sq. ft. new 3/5/7" plank white oak job that was bleached & whitewashed in 1993 to a 2000+ sq. ft. 4" Douglas fir refinish job in about 2005 to a 3000 sq. ft. new 5" knotty walnut job that was dyed and stained black in about 2007/2008 just before the recession hit and I stopped doing hardwood floors.

You are making a lot of sense. Thank you for sharing your experience with us. Here's something to consider: Could you make a video without any music? Just soften the sound of the sped up videos if you have to. Compare the results. You might also add few flashes or 'surprises' in between the sped up portions while the audio stays consistent with the sped up portion..

Just wanted to let you know how much this video helped me - I recently took over management of a floor sanding company, knowing nothing about floor sanding ( but I can do the other stuff ), and this video really helped me understand WHY crosscutting is actually extremely important to a good finished product and why my employees need to do it ( turns out, one of them already was and hiding it from the old boss, who will only use a crosscut method in extremely specific scenarios and has a freak-out in other scenarios ). Now, my guys are all basically doing it right, and it is SO obvious when we are done, because we're always flattening out horrible divots that "straight sanders" left in the past.

This had been an extremely helpful video! Thank you so much! 😊

Hi! I enjoyed your video! I’m currently in the process of refinishing my floor for the first time. Unfortunately, I stumbled upon your video after I started sanding. I’ve been only sanding with grain and started with 36 grit then 60 then finally 80. I haven’t finished it yet with the last sanding pass with 120 grit. I want to sand it diagonally to fix the waves like in your video. Do you suggest to do a diagonal pass with 36, 60 or 80? Again, the floor is currently sanded to 80 with the grain. I appreciate your help!

The marker illustration was brilliant!!!! Brought it all together

Great Video....having a laugh 😂 because you are so right! Been sanding for 30+ years and was taught from day one to always cross no matter what. Then for reasons I can only put down to laziness floor sanders begun forgetting or more likely didn't want to cross. Most floor sanders I talk to have this problem with the same excuses you mentioned, not knowing how easy it is to fix. Keep up the Great work.

Hi! Good video! Makes sense… do you do only the first sanding in diagonal? How would you sand the other grids?

Been sanding for a long time, thanks for the demo, I came across your style long ago when I started. I knew the physics, going forward at about 15 degrees from the finish point of my backwards pull, forward smooths it out and straight back straightens the grain simply because of the greater resistance put on the floor when pulling back, and if you are a pro you disc sand at 120 with a buffer for your finishes.

I discovered this fact myself on accident when refinishing a floor. I'm happy to see this post confirming it.

You're doing an amazing job! Keep up the good work, great channel!🎉 😁

Love your perfection. Very helpful channel. Well done mate.

thanks for your time and dedication. great video.

What grade/type of buffer pad do you use for buffering. Love your advice and so true the waves are unreal on my floors. 😮

I have very old pine floor with uneven floor boards, so very hard to get the grime and paint marks of it unless i go across the floor boards instead of going diagonally or along the direction they are put down, I started with a 24 grit which helped as well. i am now left with a few spots grime in-between the planks where its lower but nothing major. I have now moved to grit 40 , which is where i am confused.... do i start going diagonally ? if so do i always go diagonally when i move to a finer sand paper ?

Absolutely brilliant tutorial it has taught me so much , you should be teaching this as it's brilliant well done for posting this

That’s the thing, doesn’t matter how many years of experience you have if you keep messing up and that goes for everything. My grandpa had a saying “if job is worth doing it’s worth doing right” he told my dad that saying and my dad told me. I never got to meet my grandpa (passed away when I was a year and a half old) but though stories he became something of an idol to me.

Question: Would this be necessary for thinner boards? For example, I have about 2 1/2 inch boards. Planning to sand and refinish myself. Just getting all the info I can on the subject.

I was so excited to see the finish of the correctly sanded floor and you ended the video without showing us. I am watching this video right before bedtime, I don't know if I'm gonna be able to sleep tonight :(

Redoing the floor was some legit hard work, though after seeing the great results that came from listening to your advice and wisdom, it's actually quite satisfying work. Would definitely have been a nightmare though to have done essentially the same amount of work, but with poor technique or even good technique but after just a few moments of doing something wrong, and end up with a floor that needs to be fixed. Here on KZfaq, there is a lot of bad advice. There is also some decent or even very good advice but which lacks depth of explanation. And then there's your videos, that have solid advice AND in-depth explanations that address the subtleties that make all the difference. Thanks. I know I didn't pay to have you do my floors in-person, though I feel like I owe you a beer or something for all the helpful videos. KZfaq should add a beer can emoji next to the thumbs up, that links to Venmo.

Interesting! I have a few of questions. At the beginning you said there was a 4mm wear layer. How much do you remove when doing a complete sanding of the floor? How thick is the wear layer of a new floor before any sanding has been done? What did you mix into the sawdust to make the filler? (Asking for a friend 😉.)

Great videos! I bought a home with 6 finger Hevea/Rubber Tree Parquet floors on the 1st floor. I want to refinish the 1st floor with dark stain. I managed to find matching Hevea floor tiles for the second floor which I would also refinish. The 1st floor is ok with some uneven "fingers" and high heel marks, thinking 40 grit. The 2nd after the install, assuming everything smooth, maybe starting 60 grit. Also, in testing stain colors I sanded a tile and applied stain and noticed I hadn't sanded off the finish. Is there a easy way to know you removed all the original finish? Maybe it would be apparent when water popping?

What buffering grit do you use before staining the floor and after applying the second lacquer?

I don't have a wood floor. But man, this kind of dedication in making videos: I'm subscribing.

Hello. Thank you for sharing your knowledge. Can you validate if I understood correctly? So in order to avoid this common mistake, I should be doing at least ONE sanding diagonally, the rest can be done straight (following the grains directions). Is that right?

This makes perfect sense and I love you for this video. I really like things that make sense---thank you!

Brilliant content ! Been watching your videos for a while now. I’ve got a parquet floor that I’m planning on doing myself and was wondering if these instructions still apply ? as the boards are smaller I wouldn’t of thought so …? Many thanks 🙏🏻

I totally get this. Thanks for your in depth analysis. I come from a ceramics background. We learn pretty early to smooth out hand thrown pots, ya gotta use your tool at an angle to even out the ridges and canyons created by the pulling of a pot through your fingers. Really, well down presentation of how to get a true mirror finished floor.

Wow amazing demo, it really drives the point home. Not sure I'll do it myself but I'll be sure to ask any pros I'm hiring if they go straight all the way or diagonal!

I've been sanding floors professionally for 40+ years (2nd generation sander, learnt from my father during the school hollidays whe I was 12). I only angle a floor if it's cupped. I'd never start an engineered floor (assuming it had waterbourne coating on it) with 40 grit, I'd fast pass it twice with 60. I run straight acoss the ends with old flat 60 or 80 (halves the edging time and effort). I never ever use the machine without a belt (Not that awful string they ship with the Hummel, a propper leather weight belt crossed over at the handles), I wouls sooner run the machine without a dust bag than without a belt which I consider an intergral part of the relationship with the machine/instrument. That's just me thought (and every floor sander in NZ and Australia I've ever worked with or employed). Love your videos, I really enjoy them and appreciate your effort.

Makes perfect sense I can see you've used trial and error to find the the sweet spot the come up with the fix. Well done, I'm a handy man and a problem solver, when I was seven years old I had to take the wheel of my bike without a shifter so I came up with the idea to use two screwdrivers flat head, and some rope I think you can get the idea, and thats how I knew I wanted to be a problem solver slash handyman then I went on to learn everything I could so as I say, good job well done.

Amazing video updating veterans on the proper way to do something!

Amazing production level content 👌🏻

Hi you, please say, as end of your video confuses me a bit. So in the end you finish with diagonal sanding or after diagonal sanding you need to go straight with the line of the floor board?

As usual, great video. Just wondering what your opinion would be on sanding finger parquet blocks, the 1960s five finger basket weave ones (five in a row make a roughly 12cm square). Given that the areas of density difference are going to be localised to each individual block, as a whole they should evenly spread the weight of the drum? At any time there would be blocks running both horizontal and vertical so in theory going straight would be ok? I only ask because I’m about to do my whole flat and have some tight hallways and cupboards where going diagonal is not really viable because you’d immediately hit a wall as soon as you move forwards. Larger areas easy enough to do diagonal anyway.

How do you sand the angles diagonally where the machines doesn't reach? Diagonally by hand? Thanks for your eye-opening video!

Someone that knows their trade and not afraid to tell it how it is! I love it.

Have done a floor or two in my time, but I have to say: good stuff here. Never realized this. Two thumbs up!

I've been sanding floors diagonally just like you do in this video. I worked for a company known for the high quality finishes. You are %100 right about how to sand floors!

How do you finish the corners? Also, could you plane the floors instead?

So do you alternate straight and diagonal with each sand paper? Or just do diagonal?

How do you stop picture frames from showing where you edge at? The stain will show up a little darker around the sides

Amazing thanks so much for sharing . Great tutorial. ❤

Very good demonstration. Your comments are 100% correct. Never sand linear in line with the planks. There is wear and tear on wood especially at opening or doorways to also consider, which will be difficult to eliminate if not sanded at an angle across the long end.

Should I always use a finish sander after a drum sander? Or would a 120 grit on the drum for the final sweep be sufficient?

This video is great! It explains, in common sense, why the problem exists. Thanks mate. I will endeavour to create a good job with the correct technique 👍

Thanks mate That was super informative and I believe it will help prevent me making the same mistakes. Very comprehensive and clear explanation. Appreciate it! 👍

Good stuff. I have DIY three floors in my life. Bit different every time. In the past had skipped the fine grit and floor had bit of visible roughness to it after the glaze. Most recent floor, I skipped the drum sander and used the flat vibrate sander. Took for ever down to fine grit. Floor looks good.. but I think I have temperature problem as all the edges lifted over the year. I had plans on buffing it out and reaplying glaze in another 10 years. Not sure of the effect on the raised edges ( dark stain ). Tough part for DIYers, ore even handymen; is that they don't want to rent every piece of equipment, skipping steps along the way. Not using correct equipment.

I really like your approach, you don’t cloud it with BS! Would the same sanding technique apply to 70 year old, white oak floors, 2 1/2 inches wide?

Hi mate. Should you cross cut on the first run? So when doing 40 or 60 grit? Or which run is best to do it?

Can I just say that you're the reason I'm afraid to post videos about the stairs I've done? I already know they're shit, but I'm terrified of you seeing them! I say that with much love, learned a ton from ya. Thank you for what you do.