Sanding

Sanding · 10-13-2009, 09:28 AM

The author of a project book I'm looking at says he "dislikes sanding" but says . . .

I go through the complete schedule of 100, 120, 150, 180, 220, 320 and finally 400. Before finishing I will vigorously rub the entire project with a red, gray and finish with a white 3M pad.

That's 10 times over the piece. Seem a bit excessive to me. What do you think????

pete

PChristy · 10-13-2009, 09:39 AM

Pete, I am no expert on the sanding process but I think it depends on what the project is and what what type of finish you are looking for - I know with the lathe I have went up to 400 on some things but others I have went up to 800 - I would like to go up to 12000 when I can get the MM kit - On my scrolling I usually just go up to 400 staring with 220 - As I said at the first I think it depends on the project and the finish you want

Added: After looking at your original question - yea I think he is over doing it if he "dislikes sanding"

mikeacg · 10-13-2009, 09:42 AM

Pete,

I am with you on that one! I hate sanding because I have dust allergies and I know that I do a minimum amount of it. If this guy really hated it, you'd think he might skip at least a couple of those steps - or hire someone to do it for him!

Mike Davis · 10-13-2009, 09:47 AM

No wonder he dislikes sanding.

Sounds like Obsessive–compulsive disorder.

WoodWrangler · 10-13-2009, 10:14 AM

I know where you saw/read this ... and I too was like "dang!"

However, in my limited experience I can actually see how that schedule may actually result in LESS sanding believe it or not. Because when you skip the grits you actually end up spending more time on the "next" grit, however one in the middle would have made quick work of it. It's my guess that he's not spending a lot of time on any grit.

As for the final Mirlon pads ... not so sure about all of that. I've not noticed a lot of difference with those dang things.

scsmith42 · 10-13-2009, 11:34 AM

Hmm.... I typically go through a similar process as the author, but perhaps skip a few grits in-between.

Mikeacq - re your dust allergies, if you haven't already, try out the Festool sanding system. It captures about 99% of the dust, and they have HEPA filters available. It is really a sweet system.

Scott

Travis Porter · 10-13-2009, 11:35 AM

Seems excessive to me. I think I need to do a better job of going through the grits. I normally start at 100 and go up to 150 or 180. I am thinking of going up to maybe 220 or 320. I would think the pads burnish the wood more than anything.

I did watch Steve Wall sand some stuff up to 2000 grit with a Festool awhile back though. I was hooked and bought the sander and the 2000 grit pads although I have yet to sand anything to that level.

One thing I will say is having a sander with good dust collection seems to make the process easier and the paper last longer.

Ozzie-x · 10-13-2009, 12:26 PM

Yes, sounds like that author has made himself dislike sanding, that is a lot of grits to run through. I dislike sanding too, but it is a neccessary task to make your project look good. I'm doing final sanding today on large component of a project in walnut, and I was planning to go 120 on some problem areas, then 150 and 220 overall. I'll follow that with 320 or 400 wet-or-dry to work the Danish oil in. If your wood is reasonably smooth from preparing the stock, you should not have to sand that much. Of course I'm talking about furniture and flat work, lathe work is another matter.

Ken Massingale · 10-13-2009, 12:33 PM

I think he's making the finishing harder. On hardwood like Maple I stop with 180 or 220 depending on the paper I have on hand, all brands/types aren't the same. IMHO sanding hardwoods too fine burnishes and makes the finishing more difficult, as Travis said.
Now softer woods get a finer final grit, depending on the density of the stock being used for the project.

Mike Davis · 10-13-2009, 12:43 PM

I usually sand around 120 and 220 then a coat of finish, let that dry and sand 400, a couple more coats then 4X steel wool.

nelsone · 10-13-2009, 12:54 PM

A card scrapper will eliminate a lot of those steps with a lot less dust!

Howard Acheson · 10-13-2009, 02:01 PM

Here is something I put together a few years ago. It may be helpful.

Sanding wood--hard or soft--beyond 220 does little more than burnish the wood making staining difficult. This is particularly true if you are using a pigment stain which sits on the surface and relies on "nooks and crannies" to impart color. Softer more porous woods can be sanded to to 220 but harder less absorbent woods may stain best if only sanded to 150. The best compromise is to aim for 180 grit.

A number of years ago a large cabinet/custom furniture shop I was involved with did series of adhesion tests with various finishes and sealers. As part of this test we explored adhesion based on sanding grit. We found about the same adhesion up to 180 - 220. Beyond 220 adhesion dropped off due to burnishing of the underlying wood particularly when non-linear machine sanders were used. This was tested on birch panels. We also found that the resulting smoothness of the first coat of finish was not materially affected by the smoothnes of the underlying wood for sandpaper grits between 150 - 220.. The smoothest surface substrate for final finishes was obtained by sanding lightly after the first coat of finish was applied and dry. Which makes the case for a thinned first coat of finish.

So our conclusion was that sanding beyond 180-220 was not necessary and could be actually detrimental.

But, most important was that there was a big appearance affect if the surface was not HAND sanded in the direction of the grain using the highest grit used on the sanding machine. A flat pad sander produced a much flatter surface than a ROS. However, both required final hand sanding with the grain for optimum appearence. If not hand sanded, swirl scratches could show. Final hand sanding using a sanding pad in the direction of the grain is a must.

To carry it one step further, sanding at 320-400 grit after the first coat and subsequent coats was the optimum. No improved appearence was noticed by between coat sanding beyond 400 for varnish. 400 was the sweet spot for thinner finishes. Between coat sanding was always done by hand whether for flattening or for adhesion.

I think you will find similar thoughts in the popular finishing books but YMMV.

Finally, the first coat of ANY finish will soak little shards of wood and cause them to raise whether the surface was sanded, planed or scraped. When the first coat of finish dries these hardened shards are what causes the surface to feel rough. Sanding with 320 paper will remove these hardened shards and subsequent coats will go on smoother. So, smoothness counts after the first coat of finish, but not much before that.

The machine finish determines the starting grit. Jointers, planers, belt sanders etc, should leave a finish that allows starting with 100 grit. From there, go to 120 grit and sand until the marks from the prior grit are gone, then move to 150 and finish at 180 grit.

Plywood is factory sanded to 180 grit. Therefore, it's best to not sand plywood except with 180 grit and sand by hand. Get the first coat of finish on and then sand with 320. That way you are sanding the finish, not the wood. This avoids sanding through today's very thin surface veneer.

DavidF · 10-13-2009, 02:29 PM

Originally Posted by Howard Acheson

Here is something I put together a few years ago. It may be helpful.

Sanding wood--hard or soft--beyond 220 does little more than burnish the wood making staining difficult. This is particularly true if you are using a pigment stain which sits on the surface and relies on "nooks and crannies" to impart color. Softer more porous woods can be sanded to to 220 but harder less absorbent woods may stain best if only sanded to 150. The best compromise is to aim for 180 grit.

A number of years ago a large cabinet/custom furniture shop I was involved with did series of adhesion tests with various finishes and sealers. As part of this test we explored adhesion based on sanding grit. We found about the same adhesion up to 180 - 220. Beyond 220 adhesion dropped off due to burnishing of the underlying wood particularly when non-linear machine sanders were used. This was tested on birch panels. We also found that the resulting smoothness of the first coat of finish was not materially affected by the smoothnes of the underlying wood for sandpaper grits between 150 - 220.. The smoothest surface substrate for final finishes was obtained by sanding lightly after the first coat of finish was applied and dry. Which makes the case for a thinned first coat of finish.

So our conclusion was that sanding beyond 180-220 was not necessary and could be actually detrimental.

But, most important was that there was a big appearance affect if the surface was not HAND sanded in the direction of the grain using the highest grit used on the sanding machine. A flat pad sander produced a much flatter surface than a ROS. However, both required final hand sanding with the grain for optimum appearence. If not hand sanded, swirl scratches could show. Final hand sanding using a sanding pad in the direction of the grain is a must.

To carry it one step further, sanding at 320-400 grit after the first coat and subsequent coats was the optimum. No improved appearence was noticed by between coat sanding beyond 400 for varnish. 400 was the sweet spot for thinner finishes. Between coat sanding was always done by hand whether for flattening or for adhesion.

I think you will find similar thoughts in the popular finishing books but YMMV.

Finally, the first coat of ANY finish will soak little shards of wood and cause them to raise whether the surface was sanded, planed or scraped. When the first coat of finish dries these hardened shards are what causes the surface to feel rough. Sanding with 320 paper will remove these hardened shards and subsequent coats will go on smoother. So, smoothness counts after the first coat of finish, but not much before that.

The machine finish determines the starting grit. Jointers, planers, belt sanders etc, should leave a finish that allows starting with 100 grit. From there, go to 120 grit and sand until the marks from the prior grit are gone, then move to 150 and finish at 180 grit.

Plywood is factory sanded to 180 grit. Therefore, it's best to not sand plywood except with 180 grit and sand by hand. Get the first coat of finish on and then sand with 320. That way you are sanding the finish, not the wood. This avoids sanding through today's very thin surface veneer.

That's great article Howard. I generally go through the grits from 120 - 220 on bare wood. Spending the most time with the 120, 150 to make sure all the machining marks are out. Moving on too early from these grits will just polish the bigger scratches! After drum sanding at 120 I find I need to hand sand at 100 to get rid of the obvious straight line marks and then I can move on to ROS up to 220 then hand sand also at 220. Between coats 320-400 as Howard mentioned. Hand Sanding at 20-30 Deg in both directions before straightening out really cuts down on the sanding time.

Jeff Mills · 10-13-2009, 02:57 PM

I really dislike sanding

so bare wood rarely goes above 220. Most of the time I stop in the upper 100's depends on the wood and the project.

woodlaker2 · 10-13-2009, 03:45 PM

For most furniture projects, going to 220 has been sufficient for me. I'm talking furniture such as chests and tables. Of course I use a 22/44 drum sander for all parts that can be sanded that way. Grits beyond 220 start burnishing the wood surfaces more than I would like.