How frequently do you change ROS sandpaper discs? (and other dumb sanding questions)

[Ron Citerone]

I test with light pencil marks on the wood. The rate they sand off is visible. I'm usually surprised how long disks last.

Good idea. I might borrow that one.

[Warren Lake]

From time to time paper may not be consistent. ive returned paper more than once to one of the largest telling them it was crap. Turns out they used new adhesives in the new more chemical friendly world. At the time doing low production work so had a format this disc does this many pieces all of a sudden I was getting half the mileage? thought about it and it was paper from a last order so made a call. Happy at least they admitted an issue then took care of me showering me with new product.

[Mark Bolton]

I'm finding my sanding skills/results lacking, and wonder if I'm doing something fundamentally wrong.

Some questions:
1) Say you've got a 5 or 6" ROS with excellent dust collection and high-quality paper (Mirka or Festool, etc). Assume you're sanding a large table top (or something where 100% of the sandpaper is contacting the work). How much time do you put on a sanding disc before you consider it "worn out"? (Seems like a new disc quickly loses a bit of sharpness, but beyond that, is it usable for 30 seconds or 30 minutes?)

2) How thoroughly do you vacuum/brush off a surface when switching between grits? Is it: "Not at all - the (Festool) dust extractor gets it all", or a "I spend several minutes with the air compressor blowing every last remnant of the last grit off"?

3) How much time do you spend with each grit? Say you were sanding a completely-flattened coffee table top (~2'x4') through 120, 150, 180, 200.... is that a multi-hour procedure or a ~15 minute procedure?

4) Finally, would you do any hand sanding of a flat surface, or is the ROS the last step? Even using what I think are "best practices", a sideways-aimed flashlight shows sanding scratches that I'm worried will show up after finishing, so I end up using a sanding block to do the final sanding "with the grain". Is that normal/necessary?

Its very difficult to quantify a time or a square footage because so much of it is based on what material your sanding and what your starting with. So if your starting with material fresh off the planer, knew knives, clean, was it run through a sander, is it hickory, maple, or pine, and so on.

Our answers would be:
1. We consider paper worn when its no longer cutting well. Your spending a lot more time removing the same defects you were removing quickly.

2. None. We never clean between grits. We run vac's on the sanders and just switch and keep right on going.

3. Again depends on where your starting from. We will sometimes come straight off the planer and hit quickly with 120, just enough to about completely knock down the knife marks from the planer, then jump straight to 180 and get the rest and finish sand. We try to spend as little time as needed on the lower grits to minimize the deep scratches which will force you to step through every grit. We rarely sand to 180 and usually knock off at 150 for stain/clear finish.

4. Other than breaking edges or knocking down machine marks on an eased edge or profile that we cant hit with the RO we never hand or block sand anything. Moldings are all hand sanded.

We use Mirka Ceros', a 6" PC angle grinder style RO, a couple cheap 5" dewalts, and couple cheap 5" bosch RO's. But the Mirka's and the PC do most of the work. Mirka Gold paper (recently stopped using abranet)

For us I really try to tell people not to focus on any one thing specifically. Dont focus on time because you will sand a piece for 2m53s and the next one will need 3m30s. Dont focus on individual spots because you'll never see everything that needs sanded. Rather just pay attention, make mental notes of areas that need attention but realize you have to bring the entire surface down. Very little rocking the sander up on edge and focusing on a "spot". I think of it like mowing the lawn. Your covering the entire surface many many times. Use your peripheral vision (much more sensitive than looking straight at something) to notice defects and pick up on areas that need attention. If your sanding boards or parts. Stack your sanded parts infront of you. This way while your sanding the part your on, your also glancing up at the last part sanded and catching problems early.

All this aside. When your sanding some Hard Maple for stain your going to be doing a LOT more sanding than when your sanding Cherry or Poplar. The harder the material the less chance to skip a grit. We find Red Oak to be a bear to show sanding marks.

I would agree with the others who say dont be a mizer with your paper especially on harder materials. Change out often. Being stingy with your paper kind of works a bit when turning because no matter how fine you go, if your hand sanding with sheets, your always fighting linear scratches around the piece. So using dead paper less of an issue. But a lot of people think their 120 when it becomes dead is as good as 150 and then it turns into 180 and 220. Doesnt work. Fresh sharp paper is the key.

[Philipp Jaindl]

Abrasives arent the most expensive thing in the shop for no reason, buying good quality paper will increase its life quite a bit however as soon as it stops "biting" well its time to change. I agree with the others using worn out paper really isnt worth it.

As for how long with the Grits: untill the scratches from the coarser grits are gone, we only really use 3 Grits 80/100 , 150/180 and 220/320 for Sanding inbetween coats of laquer or the like.
Though if its a surface that wont be seen it doesnt really matter if there are some scratches left.

[John Kee]

Just a little side note when discussing Festool paper, you really should say the type you are using. Rubin was one of first wood only papers until around 2012, was relatively cheap and wore out quickly. Then they came out with Rubin 2 which was noticeably better and Granat which is one of the longest wearing most versatile papers they make. So in a lot of cases you are comparing apples to oranges as far as sanding time and longevity. One of the best papers I've tried is 3M Rubicon line but you never hear much about it mainly because it makes Mirka's expensive Abranet screens look cheap. I never noticed much difference in life between Festool Granat and Mirka Abranet, in my short time using the 3M Rubicon it was easily the long lasting.

[Dan Friedrichs]

Its very difficult to quantify a time or a square footage because so much of it is based on what material your sanding and what your starting with. So if your starting with material fresh off the planer, knew knives, clean, was it run through a sander, is it hickory, maple, or pine, and so on.

Our answers would be:
1. We consider paper worn when its no longer cutting well. Your spending a lot more time removing the same defects you were removing quickly.

2. None. We never clean between grits. We run vac's on the sanders and just switch and keep right on going.

3. Again depends on where your starting from. We will sometimes come straight off the planer and hit quickly with 120, just enough to about completely knock down the knife marks from the planer, then jump straight to 180 and get the rest and finish sand. We try to spend as little time as needed on the lower grits to minimize the deep scratches which will force you to step through every grit. We rarely sand to 180 and usually knock off at 150 for stain/clear finish.

4. Other than breaking edges or knocking down machine marks on an eased edge or profile that we cant hit with the RO we never hand or block sand anything. Moldings are all hand sanded.

We use Mirka Ceros', a 6" PC angle grinder style RO, a couple cheap 5" dewalts, and couple cheap 5" bosch RO's. But the Mirka's and the PC do most of the work. Mirka Gold paper (recently stopped using abranet)

For us I really try to tell people not to focus on any one thing specifically. Dont focus on time because you will sand a piece for 2m53s and the next one will need 3m30s. Dont focus on individual spots because you'll never see everything that needs sanded. Rather just pay attention, make mental notes of areas that need attention but realize you have to bring the entire surface down. Very little rocking the sander up on edge and focusing on a "spot". I think of it like mowing the lawn. Your covering the entire surface many many times. Use your peripheral vision (much more sensitive than looking straight at something) to notice defects and pick up on areas that need attention. If your sanding boards or parts. Stack your sanded parts infront of you. This way while your sanding the part your on, your also glancing up at the last part sanded and catching problems early.

All this aside. When your sanding some Hard Maple for stain your going to be doing a LOT more sanding than when your sanding Cherry or Poplar. The harder the material the less chance to skip a grit. We find Red Oak to be a bear to show sanding marks.

I would agree with the others who say dont be a mizer with your paper especially on harder materials. Change out often. Being stingy with your paper kind of works a bit when turning because no matter how fine you go, if your hand sanding with sheets, your always fighting linear scratches around the piece. So using dead paper less of an issue. But a lot of people think their 120 when it becomes dead is as good as 150 and then it turns into 180 and 220. Doesnt work. Fresh sharp paper is the key.

Mark, just wanted to say a particular thanks for this very nice write-up. You've given me a lot of ideas for how to "suffer less" when sanding.

[Barry Block]

A few things... I am a huge fan of Mirka abranet. I find it last much longer then traditional sand paper which I change often. When using abranet I don't usuallybother to wipe off the wood with a microfiber towel. When using more traditional types I always wipe. One thing you can do is wipe a hand across the sanded piece. If you feel grit/sand then you definitely need to wipe or vacuum as the course aggregate of the lower grit sand paper will leave scratches as you move up threw the grits.

I'm curious as to how many other people do this as no one else has mentioned it. I always wipe my pieces down with DNA when I hit 180 or higher. This raises the grain and helps high light any of the defects that I might have missed when I sanded. Raise the grain with DNA and then nock it down with another light pass of sanding. This way the grain will not raise as much when you hit the piece with finish. This creates a better, cleaner, flatter finish and if your doing a full fill then you will need fewer coats.

[Mark Bolton]

A few things... I am a huge fan of Mirka abranet. I find it last much longer then traditional sand paper which I change often. When using abranet I don't usuallybother to wipe off the wood with a microfiber towel. When using more traditional types I always wipe. One thing you can do is wipe a hand across the sanded piece. If you feel grit/sand then you definitely need to wipe or vacuum as the course aggregate of the lower grit sand paper will leave scratches as you move up threw the grits.

I'm curious as to how many other people do this as no one else has mentioned it. I always wipe my pieces down with DNA when I hit 180 or higher. This raises the grain and helps high light any of the defects that I might have missed when I sanded. Raise the grain with DNA and then nock it down with another light pass of sanding. This way the grain will not raise as much when you hit the piece with the finish. This creates a better, cleaner, flatter finish and if you're doing a full fill then you will need fewer coats.

We grain raise with water because we shoot waterborne and our planer knives are rarely fresh.

We had the opposite experience with abranet and have switched away from it. The only thing we miss is slightly better dust pickup but in addition to through the pad suction a good clean vac (dust deputy) creates a nice bubble around the head of the sander. The cheap dewalts have their own generated vac for pickup so when you plug them into a vac they are utterly dustless.

I try to stay away from solvents if at all possible and have had issue with a rouge water spots here and there on a sheet of ply or passage door so we just grain raise with water on everything. Raises the grain and turns the whole thing into a giant water spot so no surprises when stain goes on.