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Working With Fragile Woods

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I'm about to begin a project with a redwood burl top plate and a spalted maple back plate. I understand the relative fragility of these woods, and plan on doing as much work as possible with sanding tools rather than cutting tools. (It's one of the reasons I purchased an oscillating spindle sander) However, one thing I didn't consider is joining the bookmatched halves. Is it excessively risky to use a jointer, taking off a very small amount of material with each pass? I would certainly prefer this convenience to having to rig a sanding jig for them.

For you guys that are fond of working with these types of woods, what kind of methods have you used for this particular task?

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yes and no... you have a lot more control with the router - exactly where do you want to introduce it to the wood and so on. Get it wrong and the router will pull out a nice chunk but nibble away and you can get it good... tbh i still end up giving it the once over with the long sanding block

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try it, see.. If it tears out badly try another way...

thats how i build anyway, sometimes the stuff i usually do works fine, sometimes i need to find another way.

the thing with spalt is that it actually routes quite well if you go slow but i would expect a jointer to be a bit meaner.. the router and a straight edge tidied up with a bit of sandpaper on a long flat surfatce gets you wherever you want to be

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If you have a good table saw and great blade I would try ripping a nice straight line and then attach some PSA sand paper to a long piece of glass or other flat surface. You can first joint the non glue edge to lay flat against the fence.

Another method is a low angle plane but thats an expensive solution.

If all else fails try lightly spraying (spray bottle) the edge with some water to soften up the fibers first (lightly) before jointing. Then make sure you remove any water from your jointer bed. I seem to remember water being a solution to planing burl without tearout.

Edited by Woodenspoke
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Burls and spalts...both can be a walk in the park, both can be totally treacherous.

You see, both burls and spalts can have a wide 'index of delicacy' involved.

Take burls...some burls are harder than Rock Freakin' Maple...

Look at some of the burl roots out there, that stuff is hard as steel, can be harder than Ebony sometimes.

Hard enough to break or totally dull a saw blade in short order.

Or...you can get a burl that is really 'loose', and is not held together very well.

Bad Day At Black Rock if you get anywhere NEAR a jointer with that my friend.

Spalts...You can get spalted wood that for the most part, is rock hard with some lightly spalted sections.

Typically, that kind of spalt you can treat like it's normal wood (i.e., spalted Maple, treat just like regular Maple)


And both woods can have all variations in between, from 1 to 100 and all points in between.

So......the answer is......no one here can really tell you without holding the wood and having some experience behind them.

Bottom Line Recommendation: to err on the side of safety, sand them on a big flat plank.

You have a THOUSAND times more CONTROL this way.

You want to get these woods near electric machinery spinning at hundreds of revolutions per minute...:D

...It might work, ...it might not, ...up to you.

Feelin' lucky? B)

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If you are worried about tear out use a wood stabilizer first. I had a set of gorgeous pair of book matched spalted drop top. It was very fragile, so I coated it with epoxy before I started to work with it. The epoxy stabilized enough so I could join the edges and glue them together. Bondo makes a product called wood stabilizer. I have never tried it, but others have stated that it works quite well on spalt and burl. Here is a link to it on Amazon.

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The wood stabilizer will work fine, but then in that case I'd be tempted to use epoxy to join the bookmatch because the stabilizer will seal off the wood and glue won't penetrate. I think the epoxy would also make for a more visible glue line.

Avoid the wood stabilizer if you're planning to dye the wood, as it will seal it off and you'll get blotch.

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Agreed with Drak on the fragility of various burls. The camphor burl i'm using for my PRS-ish Vampyre guitar required delicacy and thought when i was jointing it as it's the kind of wood where a bunch of wood might tear out just because of the direction it's going. Even hand carving can do that. Sand all the way, as it's the only way to be sure. I prefer to err rather than kick myself later.

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If you have a good table saw and great blade I would try ripping a nice straight line

For a lot of the burls and spalts out there, this would be a recipe for an instant massacre, and kissing your money right down the toilet in extremely short order.

Just depends.

Sometimes it will work great, no problem at all.

Other times, instant kiss of death.

If you are worried about tear out use a wood stabilizer first.

With all due respect...That is like saying every snowflake is identical...

Each one needs to be assessed on an individual basis, because the answers can be very very different.

There is no one single answer to your question, it is dependant on the individual piece of wood you happen to be working with at the time.

There are times to use wood stabilizer, and there are times to not.

There are times to use 2-part epoxy, and there are times to not.

There are times to use a jointer, and there are times to not.

There are times to use a sandpaper board, and there are not.

There are times when you can dye a burl or spalt directly, and there are times when you absolutely should NOT.

There are times when you should use a Titebond type of glue, and there are times when you should use something else.

There are times when Titebond will seep up onto the top of the wood and glue down your glueboard to your topwood (burls and spalts are both subject to this), and some other form of glue should be used, or some sort of counterbalancing measure (like wax paper) should be used.

Sometimes the wood is tight and no problem, glue up as normal...

These types of woods will test you, because you need experience behind you to give you the FLEXIBILITY you need to assess each piece on an individual basis.

There simply are no pat answers when dealing with these types of woods, each individual piece will call for a different treatment.

It is all dependent on the individual piece of wood used and it's particular character.

Burls and spalts can vary GREATLY from piece to piece.

And in that case, depending on your own personal experience level, you should err to be able to control your environment as much as possible, which in this case, will tell you to sand the pieces on a flat sandpaper board unless your own personal experience tells you different.

Sanding the pieces on a flatboard gives you CONTROL over your circumstances, if EXPERIENCE is not in your corner at the time. These two forces sort of counterbalance each other.

The more experience you have, the faster you can make a decision, the more risk you can take, because you have past experiences inside your brain to rely on.

The less past experiences you have, the more cautious one should probably be, if one is not willing to 'lose' the piece of wood.

Burls and Spalts will, in very short order, reveal whether you have the flexibility and knowledge to proceed properly in an assessed environment, or even if you understand how to assess your wood at all.

This is a very different mindset than posting a question like 'should I pore fill Alder...'

This is more like asking 'should I pore fill my guitar wood'...the answer would obviously be 'well, it all depends'... :D

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If your jointer is well tuned and sharp, and you are taking very light passes. You can bring most any wood close enough to clean an edge with a straight sanding block that is 90 degree to a shooting board. There are the odd exceptions, but using a hint of common sense should allow you to detect them in a heart beat. If you pick up a piece of spalt and your fingers sink in half way through the board, or you sneeze and chunks fall off, if you see fractures that are seperating and or are loose. These should be turing a bulb on, and if you don't stabalize them at some point even sanding alone can make them fall apart.

I have worked with a fair bit of spalted and or burled wood. Common sense goes a long way, in how you should handle them. I think Drak is pretty much spelling it out for you correctly. If I had a question about these woods and or special treatments,I would probably (note; and have) asked him.


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Sounds like a lot of good advice. I'll use a sanding board, just to be safe, since this is my first time working with either of these types of woods. This should be valuable experience. I imagine that as I get further along in the process I'll get a better feel for what I can and can't do with this particular wood. I've got plenty of patience, just didn't want to go through any unnecessary steps.

Thanks for everyone's advice!

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Pics would really help here, post some pics if you get a chance! B)

...Oh, and remember, scraps are your friends!

Use all your cutoff scraps to do preliminary testing on for all sorts of procedures, from sanding and cutting to dye applications to glues. :D

Let your scraps be your organ donors. :D

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