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I'm currently finish sanding a quilted maple guitar (bare wood, no lacquer) at the moment but I've realised I don't really know how to sand it. Usually I sand with the grain so the scratches blend in with the grain of the wood and become invisible, but with this wood, there is no grain to speak of apart from the quilt figure and that goes wild all over the place. So what direction am I supposed to sand it? Straight along what would be the grain, or following the figure? Or do I just have to keep sanding to such a high grit that all the scratches have become invisible to the human eye?
So far I've gone up to 400g and it is still showing loads of tiny scratches.

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"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

I personally sand with the grain (or what would be the normal grain) even if the grain changes direction.

Are you sure you have sanded the coarse grit scratches out? It could be that you switched grits to quick and just need to spend a bit more time on removing he heavier grit scratches. I usually finish sand with 320 and don't usually see any scratches even on figured wood but if I have any concerns I will just lightly hit it with 400.

You might try using an orbital sander which will tell you if they are left over scratches from a heavier grit or if it is just the specific piece of wood you have (or you can sand in a different direction). If it is just the wood then you may have to sand it with even finer grit.

Bob

That sort of depends on what kind of finish you'll be using. I don't use lacquer, but I've read you can get adhesion problems if you go too smooth, I believe 320-400 is about as high as you can go.
If all the scratches are indeed 320 or higher, they should disappear under the lacquer.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

Thanks. How do you actually know for sure whether you have sanded out all the previous grit's scratches? I've never really paid this much attention to it before because I've only used straight grained wood which hides most scratches. Roughly how long should you be sanding the back with one grit before changing to another? I know its very subjective, but as a rough guide...

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Peter I don't know the answers to your questions,but the thread intrigues me. I'll be following closely. Good luck. Lonnie


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Boy... that really depends on the specific piece of wood. Even the same species can vary quite a bit in how easily or hard it is. If I am in doubt I will sometimes sand with one grit at about a 45 degree angle and then with my next finer grit sand at the opposit angle which will show up any missed spots. But I always finish my final sanding with the grain. (Or lengthwise from top to bottom)

Bob

Peter
If you've started with a coarse grit, say 60 or so, you need to spend some time on the
intermediate grits, 80 and 100 to remove scratches. The coarse grits leave deep marks
that must be dealt with before moving on to the next grit. Experience is the key but let's
just say you should remove the most of all the scratches depth before proceding to the next grit. For me this means spending about the same amount of time with each successive grit. Whether you're sanding by hand or with a power sander also makes a difference. It's very easy to leave behind coarse grit marks when sanding by hand.
ie. they're just plain harder to sand out. It's been my experience
that it makes no difference in which direction one sands. Well I guess it does actually.
For fastest stock removal sand accross the grain. For less obvious sanding marks sand with
the grain. Either way, properly sanded wood will have no visible scratches.
Good lighting helps. When sanding quilt maple I always use a hard block by hand or a random orbit sander in order to keep the quilt facets nice and level.

Ken

The best way to see if you've sanded off the marks from the previous grit is to hold up the body and turn it until you see it in a "raking" light. This is usually at an angle other than 90 degrees to your eyes, and should be well lit. Sunlight is really good for this so if you can be by a window you should see more. There really isn't a set time that you will spend with a specific grit, in fact usually when people try to figure out a set time for this is when they end up with scratches. You just need to sand it until it's done. Cross grain scratches will show up until you get into the finer grits, 320 and up. I don't go much above 320 before I start laying down finish, if you go too smooth you're just doing extra work for no payoff and I think if you go too smooth you can start weakening the bond of the finish maybe?

For what it's worth I've used orbitals on heavy figure wood and it kind of helps you avoid the whole sanding with the grain problem.

Western quilted maple is a bear. I pretty much hate it, don't use it anymore. If you think a guitar is bad, you should try an archtop mandolin or guitar. For me, it's not so much the scratches as the huge difference in hardness in different areas of the wood. They seem to end up lumpy, especially archtops.
Raising the grain with a mist of water does it for me. I don't go much past 320 grit myself, but raising the grain will show you where the scratches are...

There is some great advice for sanding any type of wood in this thread. I use figured Maple for most of my builds. I always prefer Garnet sandpaper. It just works better for me. I have sanded out a bunch of this stuff and I still find myself changing to finer grits before I should. I try to get as smooth as possible with no finer than 80 grit. When hand sanding I try to stay consistent with the sanding direction so I know if I am putting scratches in or taking them out. I stop at 220 or sometimes 320 grit. Polished wood will not take dye very evenly.

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http://www.cushmanguitars.com/.

A man who carries a cat by the tail learns something he can learn in no other way.
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Figured maple seems to need to be sanded forever to get it ready for finish. I sand with what is the normal grain direction. I only go as far as 220, anything more runs the risk of the finish not anchoring properly. Smaller steps in paper grit can be very helpful and make the job easier so instead of 80-120-180-220, I will do 80-100-120-150-180-220. I check often with a solvent wipe and a raking light to look at the scratches left by the paper.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Thanks to everyone for the great info in this thread. My next guitar will have quilted maple B & S so I'm following this very closely. I can share a little bit of what I've found out already.

When I was making relatively simple furniture, not guitars, I thought I knew how to sand. When I started making guitars I became aware of a problem with scratches appearing when I went to finer grades. Almost everything I've ever read about sanding emphasizes working carefully through the grades but doesn't discuss getting the surface truly flat. I traced most of my problem to slight hollows in flat areas; scratches remain in these and it's hard to sand them out. Preventing hollows requires using truly flat, relatively hard sanding blocks, fresh paper, and using only moderate sanding pressure. It's easy to create slight hollows using a ROS with relatively coarse paper (150) so I'm now following a tip from an earlier OLF discussion to only use a ROS with very fine paper. People more skilled than I am can power sand with almost any grade, but I'm not there yet. Even with 220, I am very careful not to press hard--instead, I use only the weight of the sander--and to sand all areas evenly.

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Tim Allen
"Never hurry, never rest."

Wow! That is some beautiful quilted maple!

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Thanks for the advice guys. It seems to have worked

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Wow

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Steve Smith
"Music is what feelings sound like"

Very nice indeed, Peter!

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Tim Allen
"Never hurry, never rest."

I'll join the chorus of wows! Is that oil varnish?

I'd like to add that the spalted inlay is a stunner, as well!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Thanks guys Dennis, there's no finish on it, just 1 coat of zpoxy pore filler.
The maple is a premier figure set from the wood well. I would definitely recommend them!

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Just a suggestion, don't get too hung up on "always sand with the grain". I'm not saying anyone has proposed that on this thread, but I've read it before.
I sand all my gits against the grain. I have found it makes a much flatter surface, especially with spruce. The only grit I use (other than the thickness sander) is 220. Of course, this is only prior to finish.
Give it a try you might like it.


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