Sanding a Flamed Maple

[kench]

Everytime I sand my flamed maple top I get tiny parallel brown lines perpendicular to the sanding direction.. When I sand it through the grain direction I mean.. and when I sand acrooss the grain.. I get tiny little brown points instead of those lines... It is hard to describe and I've never seen anything like that on any tutorial I've seen on net. I wish I had my digital camera here now so I can shoot a photo and post it.

It happens most when I use coarse papers like 80 or 120 grits... At first I thought they are burnt lines because I was using a power tool to sand.. but it also happens when I hand sand it very smoothly. And they are very hard to remove... 220 grit paper doesn't really work either. I just realised that they are very deep just to sand and remove it with finer papers. Chisels work better but I just finished the carving the top today and I got lots of those lines.. and I don't want to use a chisel on it and ruin the smooth carved top. Because it will require coarse sanding again.

I'm thinking that they are the pores of the wood that they came together as I sand the surface.

Is there a solution to get rid of them on an already carved top? Sanding for days with 220 or finer grits?

Btw.. I just saw those lines again on the surface that was cut by a table saw. So it's not happening only when I sand it.

[Brian]

Chances are you'll never get rid of them they are the growth lines of the actual tree. Think of them as the rings you see if you cut across the top of a branch then imagine slicing and peeling along the length instead of across and there you go ring lines along the length

[kench]

No.. They are not the growth lines or the grain. I know the growth lines. Like I said.. it's hard to describe.. They are perpendicular to the growth lines. Just 1/2" lines that looks like little scratches. Especially on the smoothest areas. I should post a picture of it as soon as I get my digital camera back from my friend.

I thought I was burning the wood first.. because I used a sander attached to my drill.. But it also happens when I hand sand it very smooth and when I cut it with table saw. But only on the top of the wood, not on the sides.

It's kind of a corruption of the pores.

[MKGBass]

Hmmm. This is just a shot in the dark, but what sandpaper progression are you using. If you skip from 100 grit to 400 grit without doing anything in between, you'd very likely be stuck with scars that you can't sand out with that fine of a grit. I've experienced something like this, but again without a pic, its hard to tell if im picturing the right thing.

[kench]

I used only 80->120->220 grit papers for now. Mostly 220 grit after finished carving. And some 3M sponge sanders.

Actually they are not scratches or scars because the lines appear only on the smoothest areas. You can't feel it with your fingers. Wood is ok on the rough areas.

I started thinking that they are pores filled with dust or something. But the lines are in order.. perpendicular to the grain direction and looks like its been scratched with a comb. And they start with a growth line and end on another. It's strange.. I've never seen anything like this before.

[82DeanZ]

I should post a picture of it as soon as I get my digital camera back from my friend.

I think a picture would help immensely. I read Brian's response carefully (I had to think about it a bit) I think he might be correct. A picture is worth a thousand words, eh?

Best Regards,

Mike.

[kench]

It might have something to do with the flame figure too. You know what those flames really are.. They are the pores of the maple that goes in the wood with different angles. So the hollogramic flame figure occurs. The figure changes due to the angle of the light and the angle of the position. Dark areas become light when you look from the opposite position.

So.. when I sanded the maple I might have distorted the pore direction and added those brown lines. Thats my theory for now. But that doesn't explain how I can get rid of them.. They seem very deep just to sand it off with finer grits, and it just adds another lines when it removes some.

[loosetoe]

kench,

Everything you have posted here tends to suggest sanding scratches.

You admit in your first post that you "sand acrooss the grain" (sic). This is a common mistake that people make Sanding across the grain will literally rip the top layer of wood exposing pores at angles across the grain that will be VERY VERY obvious as you sand to higher grits. A finish or wiping with liquid will highlight these lines even more as these pores will absorb more finish than other areas.

Further, your progression of sanding 80->120->220 will only exacerbate the issue.

Skipping grits like this will never remove the scratches left by earlier grits. Take your time and do each step:

80 > 100 > 120 > 150 > 180 > 220 > 240 > 340 > 400 > 600 > 800

If you do not remove the scratches by using progressively increasing grits, you will think all is fine until you get to a high grit (your 120 - 220 jump) at which time you'll notice the presence of the scratches that you did not remove by jumping. What you have said fits this scenario EXACTLY; and is completely in-line with your statement, "the lines appear only on the smoothest areas". MKGBass pointed this out earlier. Remember the point of sanding is two fold: 1. to smooth and level the surface and 2. to remove machining marks (like those caused by a table saw) You seem to be doing #1 fine, but at the expense of #2. Further, You say you do not get this on the sides. This can also continue this theory as the end grain present on the sides will not display the same tendencies.

Expect it to take at least a couple of hours to finish sand the body.

Barring this, I recommend using a cabinet scraper. You mention using chisels to "get the lines out", but that is like using a steam shovel to plant a rose. A cabinet scraper will remove a very fine amount of surface if used correctly and will lessen the amount opf sanding required in the long run. I really prefer the cabinet scraper methoid as when properly used you can begin finish sanding at a much higher grit (~180). Plus they are incredible cheap tools.

-Wayne

[kench]

Thanks you Loosetoe. Your post explains a lot.

But I didn't think they were scratches because I didn't sand across the grain. I did cross sanding on few areas to test it and saw that when I go ACROSS the grain, I don't get those lines.. but I get POINTS. When going through the grain.. those lines become visible... As if those points come together and create lines.

But after all.. I think you are right.. Your explaination on skipping grits makes sense. I will try harder next time when I work on the guitar.

And I have a cabinet scraper somewhere.. I will use that one too.

Thanks a lot.

[johnsilver]

You mentioned 3M sponge sanders. When I've used them, they have a tendency to throw off black grit/dust. Is is possible some of this lodged in your grain. How about blowing out the grain using a compressor?

[JPL]

This is my own shot in the dark (and blindfolded to boot) but it sure sounds to me like it's just the pores. They run from one growth ring to the next, as you sand one out another one pops up and they are perpendicular to the grain.

This is really a bad picture but does it look anything like the pores in this koa?

[kench]

Hey thanks for the photo.. They don't exactly look like mine. My scratches are very straight and look systematic... But you say it is KOA and mine is MAPLE.. So I we might be talking about the same thing.

And Johnsilver might have a point too. I didn't use 3M sponges before I got those lines. But I had used some other cheap sanding papers that were black. Next time I will test the cream sanding papers on scrap maples and see if it happens again. Cream papers throw off more grit then other papers though... but at least it is CREAM like maple...