Bowl Sanding Tools are somewhat simplistic. How those bowl sanding tools are used to get the best looking bowls can seem overwhelming at first.
I’ll tell you straight out: I used to hate sanding. I dreaded the idea of “wasting time” and wanted to get on with doing other more important things. Sanding and I have come to agreeable terms over the years. We get along fine now, and the results are satisfactory for both of us.
Who really enjoys sanding? I was that way. The thrill while turning and seeing a beautiful wood bowl emerge from a chunk of wood is dramatic, fast paced and inspiring. After a bowl is formed, it’s easy to want to call it done and move on to the next bowl. But not so fast, that’s where the bowl sanding tools and finish techniques come in.
If you have fellow woodturning friends, you know there are endless ways to sand and finish a wood bowl. There are the guys that treat sanding as a religion and will spend days finishing each piece as if it is museum bound. And then there are folks that barely sand at all and like the “natural” look of the wood.
The small incremental step from beautiful turned bowl to beautiful finished turned bowl with a great finished surface can seem time consuming and painstakingly elusive. It doesn’t have to be either.
What is the best way to sand a wood turned bowl? Well, like everything else, there are many ways. Let me share with you the way I’ve obtained outstanding results sanding my bowls. I believe I’ve managed to find a happy medium between efficiency and a nice quality finished smooth final surface.
Bowl Sanding Tools
We need to address the bowl sanding tools part of the bowl sanding tools and finish techniques equation before we go any further.
My bowl sanding tools consist mainly of an angled power drill, foam-padded sanding mandrels, and a variety of sanding disks. See my Recommended Sanding Equipment guide for all the details.
The electric drill I use is a variable speed that allows for more controlled sanding at high and low speeds. The angled neck of the drill helps to access bowl interiors with ease. I’m surprised how inexpensive this drill is online, here’s the listing.
Foam-padded sanding mandrels, with their velcro receiving top layer, make changing sanding disks quick and easy. The foam component on these pads cushions the sanding process and prevents the sandpaper from making harsh effects on the wood surface. The foam pads also help by making transition areas on the bowl blend smoothly.
My Sandpaper Back Story
Frugal parents raised me, and until adulthood, I thought all sandpaper grits were really the same. The reason for this was growing up I never saw new sandpaper purchased ever, as far as I knew. So the “sandpaper” scraps, essentially paper with little to almost no abrasive left, must be okay I thought. Nothing can be further from the truth.
Sandpaper is the critical component of my bowl sanding tools. And sandpaper needs to be treated like any other tool in this process. In fact, some turners refer to coarser grits as their “60 or 80 grit gouge.” Ha. I think you get what I mean.
But, seriously, sandpaper needs to work or “cut;” otherwise, it is not helping this process. Just like a dull gouge that burnishes more than cuts, worn sandpaper is useless and wastes time. After sandpaper stops cutting it needs to be pitched and replaced.
Maybe that’s why I hated to sand. Go Figure!
Not All Sandpaper Is The Same
I’ve graduated beyond my parents’ eternal, pinch-a-penny sandpaper-lasts-forever thinking, but I still like to save money, too. So in order to blend my money-savings roots with a quality sanding process, I purchase two different types of sandpaper.
The cost-effective sandpaper I use is the Hurricane Blue disks, and the higher quality disks I use are the Mirka brand. I’ll explain how I use these two different disks in my sanding process in a moment. Here are all available grits for each brand along with Amazon links to check the current price and availability.
|2″ Paper Sanding Disks||3″ Paper Sanding Disks|
|80 Grit||80 Grit|
|120 Grit||120 Grit|
|180 Grit||180 Grit|
|220 Grit||220 Grit|
|320 Grit||320 Grit|
|400 Grit||400 Grit|
|600 Grit||600 Grit|
The Hurricane Blue sanding disks are simple, straightforward sandpaper with a velcro attaching back. These are the super cost-efficient sanding disks which do a good job sanding, and I don’t mind using them liberally.
Mirka brand sanding disks are commonly used in the automotive bodywork industry as well as woodworking. These higher-quality pads are made of mesh fabric and cut wood beautifully. Because they are made of mesh, they can be pulled off the velcro pad and instantly become free of any dust or build up. The Mirka brand sanding disks perform very well and last much longer. The mesh pads also sand fantastically on wet green wood.
Discovering that sandpaper needs to flow with the grain was one of those ah-ha moments while learning woodworking that sticks with me. I still marvel at this simple wood-grain property. Break the rule, and the scratch marks will show.
If the sandpaper cuts against the grain of the wood, marks from the sandpaper will be visible. However, turning the sanding direction 90 degrees makes the paper move in the same direction of the wood grain, and everything looks great.
When I started turning bowls, it took me awhile to learn to determine which direction to make supported cuts with the bowl gouge. But what about bowl sanding directions compared to grain direction?
I like to turn side-grain bowls. If you look down on a side-grain turned wood bowl, there are two locations that are end grain and two positions 90 degrees away that are both side grain.
How do you sand the bowl “with the grain” if the grain is in all different locations? Flat boards are easy; bowls are very different.
The sanding purist has already clicked off this page by now, most likely when they read “electric drill.”
One theory for sanding, the purist theory, is sand by hand. Everything! Take the time and manually work through all the grits and create a beautiful final finish. Yes, that is possible, but hold on, there are other ways.
My childhood experiences attempting to accomplish anything with abrasive-free sandpaper perhaps taints my view on hand sanding. Actually, I’m not sure I have an opinion…it’s more like a reaction. “Oh, heck no!”
I have zero desire to turn a beautiful wood bowl then spend the rest of the day, or several more days, hand sanding. I’m already looking longingly at another chunk of wood to put on the lathe in a few moments.
Brute Force Sanding
On the other end of the spectrum are turners that drop the gouge and grab the power sander all without turning off the lathe. They push through the grits like shifting gears in a high-speed race to the finish.
While this approach, at least the speed part, appeals a bit more to me, the results are somewhat lacking. Also, if there are tool marks or blemishes, this aggressive bowl sanding technique won’t fix those problems.
Recall that grain direction discussion above. When all sanding is done with the lathe turning, the sander is cutting against the grain half the time. Against the grain, sanding leaves scratch marks no matter what the final sanding grit.
My Sanding Technique Process
An attempt to blend speed with quality is my approach to using my bowl sanding tools to obtain the best results for me. I’m not looking to make my finished bowls museum quality, but I also don’t want visible scratch marks, either.
Don’t worry; I’m not going to suggest any hand sanding. Rarely will I hand sand a bowl. I still want to get the sanding over with as soon as possible and get to the next bowl blank.
Examine the bowl surface for any trouble areas: tool marks, gouges, or a nub or divot in the center bottom. If the center bottom does have a nub or divot, use specific bowl bottom techniques to fix the area before you start sanding.
Depending on the extent of any trouble areas, start with a coarse sanding disk, perhaps 80 grit. With the lathe off, sand with the grain (more about this in a minute) just in these trouble areas. With the trouble areas fixed, move up to a finer grit sanding disk.
Turn the lathe at a slower speed, around 300 rpm, begin sanding the entire bowl surface. Sand from rim to center and after a short time, stop the lathe and address the areas where the rotating sanding cut against the grain. The locations to inspect are usually the end grain and transition areas between the side and end grain.
After finding the newly created scratch marks in the end grain areas, with the lathe off, sand with the grain to remove these marks.
I then move up to the next finest grit sandpaper, once the surface looks smooth and free of scratches. With the new sandpaper attached, I will return to step three and repeat the steps three, four and five.
Finesse The Trouble Spots
Once you become aware of these trouble areas, you will instinctively know where to find them. Potentially, anywhere the sanding disk cuts across the wood grain will produce scratch marks.
Surprisingly if you run across an area that is problematic, it’s very common to rotate the bowl 180° and find the same issue on the other side of the bowl.
Take a look at the graphic below. While the bowl was spinning, the side grain areas were in line with the side of the sanding disk. So, they were cut “with the grain.” However, the end-grain areas and the transitional areas in between were sanded at least partially “against the grain.”
The red and yellow marked areas are what needs addressing with the lathe off. These trouble spots just need a little more attention before moving on to the next sanding grit.
Power Sanding With The Grain
The idea of power sanding with a spinning disk with-the-grain might seem odd at first. However, turning with the grain is very achievable. It does take a bit of practice.
At no point should the entire circular sanding disk engage the wood bowl surface. If it does, the sanding pad grips the wood and vibrates wildly to free itself. Instead, the best sanding action is on the side of the sanding disk.
I’m right handed and hold the electric drill in my right hand. Turning my wrist slightly angles the sanding pad and utilizes the right edge of the pad only.
Using this right side of the pad, which turns in one direction, we can sand with-the-grain. Simply think of the right side of the sanding pad as being linear and line it up with the grain as you sand.
Keep the pad moving without stopping in one area. A long pause can remove too much material and leave a mark. Also, let the sanding disk do the work. You should not be pressing hard on the disk. If you find yourself pressing to make the disk sand, it might be time to replace the sanding disk.
Turning and twisting your wrist will position the sanding pad side in various locations to better line up with any wood grain flow. In step four described above, I typically work from the outer rim around the bowl several times sanding the grain until I reach the center. The active lathe sanding only takes a minute or so.
The better your turning skills get, the less sanding you will do. I used to start at 80 and go to 120, 180, 220, and then 320. Now, most of the time I only sand 180, 220 and 320 grit. Three grits reduce the sanding time even further.
Don’t Cross the Center
With the lathe spinning, like in step three, do not cross the center line during power sanding. Stopping at the center may seem strange at first, but crossing the center line equals double sanding.
The area sanded right before reaching the center point is the same area on the other side of the center point. If you cross the center and sand on the other side, a trough or shallow valley will begin to form around the bowl bottom center.
Sandpaper Grit Progression
The purpose of progressing through various sanding grits is to remove the scratches and marks from the previous sandpaper grit.
The sandpaper grits need to progress in a way that is most efficient time-wise but also does the job of removing the previous marks.
When I sand, I use the “fifty-percent up” guideline. Each sandpaper grit is fifty-percent finer than the previous grit. An example of this progression is 80, 120, 180, 220 (or 240 depending on manufacturer), 320, 400, 600 and so on.
If you have mastered removing tool mark tricks, then you don’t need to start with a coarse grit. Depending on how smooth your surface is, you may begin at 120 or 180.
I usually start at 120 and proceed up to 320. That process is only four changes of the sanding pad and does not take much time. If you’re starting out, you may need to spend more time with 80 grit smoothing off tool marks before moving up through the process.
320 grit is my stopping point because my favorite food safe wood bowl finish, and other oil-based finishes need to be able to soak into the wood pores. Sanding smoother than 320 closes the wood cell pores and makes it difficult for the oil finish to penetrate.
Green Wood Sanding
Yes, you can sand green wood. High-quality sanding pads work best. If a wood is sopping wet, I will let it turn on the lathe at a slow speed for ten or fifteen minutes. Pausing a bit after turning the surface usually allows enough evaporation to make sanding much more manageable.
Here’s another reason why I have two different types of sanding pads in my bowl sanding tools arsenal. Green wood can be nasty to sandpaper. The wet fibers combined with the tree resins can quickly gum up regular sandpaper rendering it useless.
The downside with the Hurricane sandpaper pads is they don’t last long on wet green wood. They will cut green wood, just not as long as the Mirka brand sanding pads.
Mirka sanding pads, made of a mesh material, are easy to clean off, usually just pulling them off the velcro foam pad is enough. A quick shack off and they go back on ready to continue.
The downside of the Mirka pads is that mesh material will grab the irregular surface of a natural edge bowl and tear. The Hurricane Blue sanding pads being a flat and even paper material do not grab rough edges often and do fine on drier woods.
So there are several trade-offs between performance and expense when it comes to sanding disks. For me, I find blending the features of two different types of pads works best.
These are the wood bowl sanding tools and finishing techniques I use in my bowl making process. And here is my Recommended Sanding Equipment.
Your process might be different, and that’s perfectly fine. Please leave a comment below and let me know how you sand and what bowl sanding tools you use when finishing your bowls.
Once you’ve Sanded your bowl, you’ll want to know more…
• SALAD BOWL FINISH – FOOD SAFE? SURPRISE – 3 SAFE OPTIONS
• MAKE SHELLAC – HOW TO – WOOD BOWL FINISH
• MY FAVORITE FOOD SAFE WOOD FINISH – WATERPROOF ALMOST
Happy Turning (and Finishing),
Great article, I enjoy learning from you. I have been turning less than a year, and after sanding to final grit, either 320/400/600, I’ll burnish with shavings and then apply the finish coats. The surface looks good, but is that the best time to do it, or is it better to burnish after the finish is applied? Thanks again,
It’s up to you. I like to sand to 320 or 400, apply a finish, then polish. I’m not trying for museum-quality finishes on all my pieces. There is nothing wrong with applying more effort. Finishing is one of those areas that is really up to you and what you want for your piece. All the best to you and Happy Turning!
It looks great, Kent! Thanks for sharing your tips. Can’t wait to try this using my new drill!
Sounds great. It makes sanding very nice. Enjoy and Happy Turning!
What is the best finish for pecan I have a lot of it and I want it to look really good
I am new to this but can already tell I am hooked
Well, it all depends. I finish pecan pieces in both a satin, using Tried and True Original and I finish it with a base coat of shellac and a high-gloss top coat of lacquer. Both look great, but it’s just a preference. Try both and see what you like.
Do you have a recommendation on the optimum RPM to use on the drill used to spin the sanding discs. I recently purchased an inexpensive electric drill specifically for sanding bowls. I didn’t think about the RPM of the drill when I made the purchase, but after getting the drill home, I learned that the max RPM on the drill is 650 RPM. Is that fast enough? Many of the more expensive drills that could be used for this purpose have a Max RPM of around 1500. Does the RPM of the sanding disc matter, or is that not a concern?
Interesting question. I hadn’t considered this until now. The drill speed doesn’t need to be that fast. And the lathe speed is usually half of the speed used while turning. Simply the fact the two surfaces are turning creates plenty of motion to sand very effectively.
Great presentation. Found this on the web as I have found myself taking a lot of time sanding bowls. Now I know why!!!!!. I used your technique and I must say I cut my time down dramatically and with less utterances of foul words coming out. Thanks for your help!!!!!!!!!!!!!!!!!!!!
LOL, less foul words is always better. LOL, Glad this helped! We all want a good finish, but we also don’t want to be sanding until our joints hurt. Happy Turning!
I use an air powered mini random orbit sander from Ken Rizza. It holds 2 or 3 inch sanding pads and has become my go to sander for bowls.
Will you please explain the reverse function when it comes to sanding. I also can’t find any clear information about using reverse for turning bowls. Any clarity on this subject is much appreciated.
Cheers, Al (South Australia)
Yes, I’d be glad to help.
Some people like to reverse the lathe for some of the sanding, in order to remove fibers that may be laying over instead of sanded away. Similar to shaving in opposite directions.
Be sure your chuck is fastened to the headstock with a set-screw so it doesn’t work off in reverse direction mode.
Personally, I don’t do this, but I can see where it might be of benefit.
All the best to you and Cheers!
What a fantastic resource you are, started turning just after Christmas and have to let you know your site is my “go to page” ..Thank you.
I would be interested to know your thoughts on a bowl that I turned recently for a tree that had died, was left standing, stripped of bark and then fell, I believe its white oak, but not sure. In creating the bowl there was a fait a mount of tear out however I got past that hurdle, and when finished, sanded and went up to 320 and applied Tried and True, once in the house and use a couple of times the surface became rough and raised.. should I re-sand ? Should I apply more Tried and True ? What grit do you recommend before applying T&T ? Many Questions! It would be great to hear your thoughts and Ideas Many Thanks Andrew
Thank you for the kind words and I’m thrilled this site is your goto wood bowl turning source!
Your question has a couple of variables that need to be considered.
— If the wood was fairly wet, yes over time as it dries it may get some raised grain.
— Also, oak is a beautiful wood that is either loved or hated by the turners I know. I like it very much, but I have to temper that with the fact that it dries like no other wood I’ve seen. I like to think of turned oak bowls more like leather than wood. Ripples and movements seem to never stop coming, even after many applications of oil finish.
— If you apply multiple coats of Tried and True you will need to let them cure so they aren’t sticky. Be sure you apply the first coat very thin with zero build up. If the wood surface is discolored by the oil, that is enough finish.
— Yes, you can reapply Tried and True oil. I usually put the first coat on with T&T Original which contains beeswax. Subsequent layers, I will use T&T Danish Oil which is just linseed oil. This helps penetrate into the wood until the surface wood cells become saturated with finish.
— Again, oak will dry out and can appear as if no finish was even applied. So you may need to add many layers of finish. Make each layer super thin and wait for it to cure. Basically wait until the surface just feels smooth and has no hint of stickiness.
Let me know if that helps and all the best to you!
As always, sage advice Kent, thank you so much for spending time to reply. I obviously need to learn, more about Oak, as its an easy resource for me to get hold of, additionally an old dried elm tree fell on our property and that’s going to be my next project. It occurs to me that information about different wood types is equally important as to their status ( dried vs wet ) etc etc.
Thank you again for your advice and help.
Yes, every different tree has plenty to discover. If the elm you have is like the one I got last year, you’re going to like it. Enjoy!
A very experienced local turner and friend clued me in to wet-sanding. He mentioned using mineral spirits, but I didn’t like the lingering smell in the wood, and the idea of using that chemical on items that would be used for food didn’t appeal to me.
I discovered a great alternative – butcher block conditioner, available at your local building supply center. It contains food-grade mineral oil, beeswax and carnauba wax. I smear some of this on the bowl or spindle turning while it’s still on the lathe and use progressively finer grits of strip emery paper, adding more conditioner as needed.
The oil/wax and sandpaper creates a medium-dry slurry, or kind of a paste, that helps keep the pores of the sandpaper clear, enabling the cutting surfaces to do their job. Using the oil will even bring a gummed-up old piece of emery paper back to life instantly, clearing out the resins stuck in the grit. You’ll get cutting action from a piece of emery paper that you normally would have tossed out long ago.
This is a great side benefit for a frugal woodworker, but the best part is that if you keep around some pieces of emery paper in varying states of wear, you basically increase the range of grits you have to choose from. I usually have several pieces of 320 and 400-grit paper in various states of wear. A very worn piece of 400-grit, when used with the oil/wax conditioner, is like using a piece of 800 or 1200 grit. You can get a piece of worn paper to cut that just feels like a piece of smooth ordinary paper.
This technique quickly produces a very silky-smooth finish with some nice depth to the grain. I will then often finish the piece with another type of salad bowl finish or friction polish.
It also keeps the sanding dust to a minimum and smells nice. 🙂
Kent, what an amazing website! I stumbled upon it, let’s see, about 3 hours ago and can’t seem to stop reading. Well done sir.
Thank you for sharing this wet-sanding information!
I’m so glad you found TurnAWoodBowl.com.
All the best to you and Happy Turning,
To quote Jerry, I stumbled on your site a few days ago and agree it is amazing. As you promised, so much info all in one place.
Thank you so much!!!
I’m thrilled to help and glad you found me.
All the best to you. Take care!
Love your tips!
When I’m finishing the tailstock-end of a project, I always seem to have a pit leftover exactly in the center. I can’t seem to scrape it out or sand it. I know that the center of the wood is turning at a much slower speed than the outer edges, but try as I might, I can’t eliminate it no matter how fine or coarse the sandpaper. What am I doing wrong?
I believe you’re talking about finish sanding the inside bottom of the bowl. If you cross the center point of the bowl with it rotating, you’re sanding the center area twice. When I first learned this I had to think about it a bit.
If you sand from the bottom up as I do, then cross the center point, you just sanded the area around the center twice. This makes a valley or groove around the center point. Instead, sand up to the center point but do not cross the center, with the lathe running slow. Here’s the key. Stop the lathe and sand the center area smooth, sanding with the surface grain pattern.
Just don’t cross the center point with the lathe running and you should be fine. Let me know if that helps.
my bowls are mostly end grain
Thanks for writing.
Check out this recently released article I made just to address your question about grain orientation.
Let me know if this article answers your question.
Being new to turning (so new that I haven’t even bought my lathe yet 🙂 ) I am having a hard time visualizing from your picture of the “bowl grain direction” how you actually turned the bowl. Am I correct to believe that you are making the bowl from the side of the log instead of the end grain? Thanks and really enjoyed your article…I saved it to refer back to once I actually start turning bowls.
Yes, most wood bowls are side-grain oriented. Of course, there are also bowls made with end-grain oriented wood. It can be done either way, but for the most part, bowls are made with side-grain oriented wood. I’m writing an article now about wood orientation, so stay tuned.
Thanks and Happy Turning,
Hi Kent, I am enjoying your many excellent “talks”.
In context of sanding, are there any other circumstances other than green wood where you prefer to use the mesh over paper? Marc
Thanks for the question. In general, I use the mesh pads most of the time because they last longer, grip the velcro backing well, and perform very well compared to the paper sanding disks. I usually use the paper disks when I know the wood is going to eat them up, like when it is green for example.
Hi – I just finished turning a bowl / vase made from 10” x 10” laminated plywood “scraps”. The grain runs all over the place and appears to be quite a problem to sand without getting scratches. Any recommendations on getting this thing smooth other than hand sanding it?
Sounds like an interesting project you’re working on.
Hopefully, you still have a way to attach the piece to the lathe.
If so, I would recommend making very thin finishing cuts to leave the surface as smooth as possible. Start by sharpening a smaller bowl gouge, perhaps a 3/8″ gouge. Turn the lathe up as fast as possible without creating any vibration, staying within safe limits, see this article. Now make a very thin and slow final pass basically shaving the surface. This cut should only be using a very small fraction of the gouge’s bevel cutting edge.
For deeper tear out or marks on the surface, you may need to make a couple passes like this. Be sure the gouge is perfectly sharpened and make the feed rate of your gouge very slow and deliberate.
Let me know if that helps.
Helpful as always and always more questions.
Have you used a random orbital sander? Compare that to the basic drill please.
On a well turned bowl of average size (you define that) what is an average amount of time you spend power sanding and hand sanding?
I have never used an orbital sander on my bowls. The disk pad would be too large. Two and three-inch diameter sanding foam pads and sanding disks are all that’s needed for bowls usually.
Sanding time depends on many factors; wood hardness, moisture content, bowl gouge skills, etc. On average a 9-12 inch bowl takes about 5 to 10 minutes to sand. If there are trouble areas then the time might increase a bit. I do no hand sanding usually, only lathe on and then lathe off sanding all with the electric drill. I spell that out in this article.
Absolutely excellent article Kent, as always. Your effort and dedication is noticeable and it makes this the best bowl sanding guide I’ve read. Keep up the great work – it’s appreciated!
While I am up in age and self taught turning sanding always been a mystery to me. Like you I wanted to be turning not standing there rubbing my bowl with a piece of paper. I did a respectable job using 3 or four grits and sanding the entire surface No one ever really told me what I was doing wrong. You article opened my eyes as to what I was doing wrong. Finally someone opened my eyes to exactly what I was doing wrong. I finally turned and finished a bowl that I was truly happy with. This is not a instant answer to all sanding issuers but it’s a excellent starting point. From the first bowl they have improved, now I am turning out bowls that I am truly proud of. This does prove you can teach an old dog new tricks. Thanks for the tips they are a real learning tool. Charles Harmon
Ps: It also cut the time spent sanding to produce a great surface.
Charles, Thank you so much for the comment I’m so happy to help you out with your sanding technique. Please let me know how else I may help. Happy Turning!
I have a friend who loves to finish and he does a great job of sanding and finishing but spend many hours doing so. I had rather be turning.
You did an excellent job of describing all details of sanding and appreciate you comments.
How long does the Neiko sander last?
Thanks for the compliment John. Well-sanded bowls are important, but I’d rather be turning too. So, why not find a happy medium.
The sander will last a long time. I’ve had mine for a couple years now. The big thing is to blow out the dust. I use my air compressor to blow out dust from the vents on the sides of the drill.
Gosh after reading how you sand a bowl, I am at a loss! I just recently starting turning bowls, which mostly is stacked and glued for bowls because I’m practicing. Even when I get better I may still do this, less expensive and I like how the bowls look. Depending how I use the finishing tool, I start at 120 grit but my lathe is on at about 910 rpm. I don’t have a mentor, so I watch you tube or read and go from there.
I have been turning for years as I turn other creations but bowls is a challenge for me. Sanding will also be a challenge for me at the moment. The blocks of wood is side grain, so the edge of the bowl is the end grain. That is my issue right now and any help or additional advice is much welcomed.
I came across this site by accident and I’m impressed and will keep coming back. Thank you so much for sharing all of your knowledge with us who love to turn.
Thanks for writing.
The end grain needs to be sanded with the lathe off. Use the edge of the sanding disk and sand with the surface grain of the wood.
When you sand only with the lathe running, you are sanding with the surface grain half of the time and the other half against the surface grain. When we sand against the surface grain we leave scratches. This is why you then need to turn off the lathe and sand the end grain areas with the surface grain. Take a look again at the images above.
Also, turn the lathe speed down when you do the first sanding portion of each grit. There is no need for fast lathe speeds because the sanding disk is doing all the work.
Let me know if this helps.