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Boss Hog's picture

I can sand cherry to a very smooth finish without any great difficulty. However, when I try to sand oak (red or white), I cannot achieve the same or even similar smoothness. I'm using the same sanders and sand paper, and I take even more time with the oak than I do with the cherry. Do I have unrealistic expectations or do I need to treat the oak differently than the cherry? For both, I use a Festool random orbit sander, a Portter-Cable sheet sander, and various types of sand paper, usually starting at 50-80 grit working up to at least 320 grit.

Dave45's picture

(post #88535, reply #1 of 9)

Oak has a much different grain than cherry and that "roughness" you're feeling is probably on the grainy areas which are softer than the lighter areas which have tighter graining.

To get that glass smooth feel, you may need to use a grain filler before sanding.

Boss Hog's picture

(post #88535, reply #2 of 9)

Thanks. Can you recommend a grain filler? Are grain filler and wood filler the same thing?

Dave45's picture

(post #88535, reply #4 of 9)

I've never used fillers, but I've seen them in woodworking stores. If you Google "grain fillers" you should find lots of sources.

Are you Boss Hog the truss guru from Breaktime?

If you are, when did a truss guru get into fine woodworking? - lol

Boss Hog's picture

(post #88535, reply #5 of 9)

No, I'm not. I don't even know what a truss guru is.

SgianDubh's picture

(post #88535, reply #3 of 9)

I suspect you may be expecting to get oaks smoother than it is possible to do so. Cherry is what is known as a fine textured wood, or fine grained; it is also 'diffuse porous'.. It does have different grain texture produced by spring growth wood and later season wood, but it is not very different.

The oaks, 'ring porous' in nature, on the other hand produce wood of markedly different character during the spring and the summer. Spring grown wood is very open and porous to enhance the transportation of sap up the tree during the spring rush. Late growth wood is less adapted to the movement of sap, so is therefore denser and stiffer, better  able to support the tree. The result in a plank is bands or strips of porous open pored wood sandwiched between bands of denser material.

When sanding you eventually reach a grit size that is smaller than the pores in the wood, and in the case of most common oaks those open pores of spring growth generally match about 150- 180 grit paper. Cherry, with its much finer pores has pore openings that meet  the exposed surface that are much smaller; I'd have to guess at the matching size, so I prefer not to.

You just can't get oak to sand to a smoother surface to the touch than those most open pores in the wood, ie, the spring growth bands, so about 180- 220 grit is about as far as it is worthwhile sanding to. Cherry, finer textured as it is, will sand much smoother and you can get it highly polished with abrasive papers prior to applying a finish.

The value of sanding wood to grades such as 320 or 400, or even finer is dependent upon what you are trying to achieve. In many circumstances sanding any wood species beyond about 180- 220 grit is non-productive or counter-productive, eg when applying a film forming finish over the top. In other cases sanding that fine and beyond may be beneficial, but almost certainly not in the case of any of the oaks unless, perhaps, you are incorporating a grain filling job in the polishing procedure. Slainte.

Boss Hog's picture

(post #88535, reply #6 of 9)

Thanks. That is very good information that I didn't know.

Eireannach's picture

(post #88535, reply #9 of 9)

I recently got some ancient kauri wood (30,000-50,000 years old) and sanded a test bit of it to 1500 grit.  It's mirror smooth, shiny, and when I reached 600 grit the grain texture blossomed.  I thought it was a pretty wood at 220, but now it is beautiful.  I've never sanded a wood to that degree of polish before - it's cool wood.

Ar ghrá ruda adhmadóireacht. (For the love of woodwork)
forestgirl's picture

(post #88535, reply #7 of 9)

Boss, I'll throw out an option that's a bit easier than using a grain filler, but may suit your purposes depending on the type of project and what kind of finish you're using.  That being "wet-sanding".  I've used it on a couple of red oak projects (red oak has bigger pores than white oak).

Wet-sanding creates a slurry of the sawdust created by sanding to partially fill the pores in the grain, leaving a smoother surface than dry-sanding.  It would not provide the so-called "mirror finish" that a top-notch grain-filled wood would, but it's very nice to the touch.  Click here to see my post on wet-sanding from awhile back.  Do an advanced search to find others' recommendations.  Everyone does it differently!

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

Boss Hog's picture

(post #88535, reply #8 of 9)

Thanks. I'll have to get some wet-dry sand paper.