Sandpaper and Sanding

[rrich]

You need to ask yourself the question, "Which grit of sandpaper do I use the most of?"

The answer should be one of the coarser grits. (80,100 or 120) Right now some of you are thinking, "Rich is up in his nightie and wandering about the yard." The reality is that when sanding, the first task is to SHAPE the wood as desired, then to remove tool marks.

What happens is that the 80 or 100 grit does a nice job of smoothing those joints so that the joint can't be felt with your fingers. Then the over all shape is smoothed.

After shaping and smoothing the surface of the wood seems rough and fuzzy. Here the finer grits of sandpaper are used. The finer grits are used to remove the scratches from the coarser grits.

(BTW - This is exactly the same principle as when we sharpen tools.)

So after shaping and smoothing, 120 grit is used to clean things up. Then we go through 150, 180 and 220 grits to prepare the project for finishing.

Generally for stains, we don't want to sand much finer than 220. If the project is sanded to finer than 220 the stain may blotch. The finer the grit used in the sanding process, the likelihood of blotching increases.

When I'm fuming some Oak, I'll sand to 220 grit. After fuming I'll sand to either 320 or 400 grit before applying an oil finish.

Sanding to 600 or 800 grit is a good practice for end grain when a natural finish is desired. The higher grit tends to close the end grain and deters the absorption of finish giving the end grain the same color as face or edge grain.

[admin]

Very informative! I didn't know that about end grain. I'd just given up that end grain is going to look differently no matter what I did. (Always looking drier than the rest, etc).

TJ.

[JBark]

The training I received in a pretty good furniture shop went like this. If we used a router or shaper to make a moulding we sanded with 100, then 120, 150 and ended with 180. Stock going through the jointer and planer would be scraped with a Stanley #80 and then orbital sanded with 150 and 180, then by hand with 180. We were told by our finishers not to go beyond 180 as it sealed the pores and made it harder for the stain to penetrate. Carvings were "cleaned" up with 180. If one was shaping a cabriole leg it would be rasped and filed or spokeshaved and them followed up with hand scrapers. We would follow this with sandpaper, probably 150 and then 180.

Any tool marks were removed by scraping and/or sanding. I never learned of any specialtreatment to end grain. It would receive the same sanding grits as other surfaces but often required more of that sanding to look clean.

John

[dcarter636]

Since I mostly make flatwork projects I rarely use sand paper for anything rougher than removing tool marks. Shaping and leveling is accomplished more uniformly with cutting or scraping tools. Too many times I've made tapered edge radii or wavy surfaces using sand paper to remove stock that should have taken off with a plane.

My typical sanding schedule is 150 to smooth large surfaces planer, and jointer ripples, or table saw marks then 220 and perhaps 320 for wipe-on finishes. Most router marks are taken care of with 220 then 320.

I'll have to try the fine end grain sanding; it would be nice to have a way to make end grain finished color better match that of the long grain.

[wisardd1]

My experience is that the finer the grain the more uniform the stain and the less blotching. I would liken it to using shellac or some other wood conditioner. Even more so, dye at some of the lower grits, then finer grits for uniform grain. But remember, I don't really know what I am talking about, I am still trying to figure out what works for me.

dle

[deepsplinter]

I worked in a custom cabinet shop way back when. Everything (face frames & doors) went through the big drum sander with 100 grit. Then we'd sand it with 100 and 120, using a 5" dynabrade. On raised panels, we'd go through the same process, but finish up by hitting the end grain with 150 grit on a little electric finishing sander. It seemed to be good enough.

Now that I'm on my own, (for most flat work) I'll go to 150 with my ROS, then finish up by hand sanding with 150.

[sawduster]

Lately I've seen several articles in the magazines recommending sanding to 180 grit if you are going to be staining. I would further add that the last sanding should be done by hand with the grain. Even 220 grit will leave scratches that are visible, so the final sanding by hand with the grain lines the scratches up with the grain so that they are not as visible.

Sanding with finer paper tends to burnish the wood, making even acceptance of the stain difficult. But, sanding with finer grits also makes the natural grain sharper and more visible, so if you're not going to add color to the wood, then sanding to the finer grit, IMO, makes the wood more attractive.

Using hand planes to smooth a surface also has something of a tendency to burnish the wood, so if you are going to stain the wood, it is recommended that you sand lightly with the grain with 180 grit by hand after planing.

[Ruffnek]

Jan 4, 2010 8:21:50 GMT -6 sawduster said:

Using hand planes to smooth a surface also has something of a tendency to burnish the wood, so if you are going to stain the wood, it is recommended that you sand lightly with the grain with 180 grit by hand after planing.

When using a card scraper, do you pay attention to the grain direction like when planing? I'm not talking about going across the grain but rather, scraping against the grain?

[sawduster]

Jan 4, 2010 10:00:08 GMT -6 Ruffnek said:

Jan 4, 2010 8:21:50 GMT -6 sawduster said:

Using hand planes to smooth a surface also has something of a tendency to burnish the wood, so if you are going to stain the wood, it is recommended that you sand lightly with the grain with 180 grit by hand after planing.

When using a card scraper, do you pay attention to the grain direction like when planing? I'm not talking about going across the grain but rather, scraping against the grain?

You do get a little bit cleaner cut when using a scraper "up hill" into the grain as you would when planing. But, there are times when you have reversing grain that makes it difficult or near impossible to stay in the most appropriate direction to the grain, and the scraper will generally give you less tear out than a plane. The area around knots in your stock sometimes has grain going in all sorts of direction, and a scraper will usually give you a better job in those cases.


Here is a quick pic I made to show what I mean by planing and scraping "uphill" into the grain. The long grain surface adjacent to the surface being worked is the one which will tell you which direction to plane.

Looking at the pic you can easily understand why planing in the opposite direction will cause tear out while planing as shown will prevent it. In the direction shown, you will be shaving off the ends of the grain without lifting them up. Going the other way, the edge of the blade wants to lever up the wood fibers and pull them away from their neighbors. This action yanks the fibers loose rather than cutting them cleanly.