Spalted Maple Strength

[Prashun Patel]

I have a slab of spalted maple that is about the right size to make a chair out of.

I'd only lightly spalted, and there are really no soft spots anywhere.

Is this a poor application for spalted wood?

Is there anything I should know b4 I go down this path?

[george wilson]

It would probably be o.k. for a thickish seat. maybe not for thin legs. You need to be specific about the chair design. Spalted wood is very bad to breathe,like while turning or sanding.

[Prashun Patel]

Thanks for the tip, George. Here's the chair:

http://www.finewoodworker.com/baur-stool.html

But I'll be cutting the legs down to be more of an office chair.

[george wilson]

That chair is going to be a LOT of mostly rasping,or other hand tool work. I'd prefer to use wood that I know I can trust,and do not have to breathe mold from.

It would be very bad to make that chair,and have something break down the road.

[Prashun Patel]

I hear ya. I just made a rocker that was similarly sculpted. Despite my best efforts with dc's, air cleaners, and respirators, I was still blowing brown walnut dust out of my nose more often than I liked.

[Cody Colston]

Shawn,

Seri Robinson is a member of the turning forum and an expert on spalted wood. In fact, she will soon receive her Phd on the subject! Here's the announcement: http://www.sawmillcreek.org/showthread.php?t=131849
I'm sure she would be moe than happy to answer any questions you have about spalted wood if you PM her. She's a turner so she may not venture into the Flat Earth Society portion of the forum. :)

If you subscribe to FWW online, she has several articles there about spalted wood and had this to say about the dangers of it:

There is a misconception among many woodworkers that working with spalted wood is particularly dangerous. Most fungal spores are about as harmful to a healthy adult as wood dust, so if you sand spalted wood, wear a mask. However, people with immune system disorders should not work with spalted wood.

BTW, that barstool you linked to is awesome.

[Homer Faucett]

I echo Cody's statement. As long as the wood is not punky, I see no reason not to use it. I have used spalted silver maple to make a cabinet that has held hundreds of pounds of candles for the past four years. As long as it is spalted and not rotten/punky, I see no reason not to use this as long as it is properly dried.

With regard to spores, let me first say that it is my understanding that it is not mold that causes spalting, but rather a decay fungus (white rot fungus and blue spalt fungus). Here's a great article on spalting: http://www.hiltonhandcraft.com/Articles/Spalting_a_Fungus_Amongus.asp .

I have turned and cut a fair amount of spalted maple, and even some punky spalted maple, and never had an issue with reaction, although cocobolo gives me fits. That doesn't mean that you should not take precautions, however.

Personally, I'd use it! Spalted maple is one of the most striking forms of native lumber, IMHO.

[Seri Robinson]

Although I already responded to a private message, I might as well repeat myself here.

In general, you really shouldn't use certain types of spalted wood for load-bearing applications. White rot and its associated zone lines are very destructive. The stains, however, do not affect the strength of the wood and would be fine to use.

For a chair with lightly spalted wood, I'd keep the spalted wood away from supports and the rocking pieces themselves. There is no problem using it for the arm rests, back, seat, etc.

As for health, spalted wood isn't inherently any more dangerous than normal wood, and a lot better for you to breathe than many tropical woods. I've written about this issue extensively both here:

http://www.finewoodworking.com//blog/woodworking-life/tag/spalting

and here:

http://web.mac.com/kaysa_gabriel/Northern_Spalting/Blog/Blog.html

And Cody, I got my PhD in February. Woohoo! Now I'm a post doc, researching spalting full time.

[Cody Colston]

Congratulations, Seri.

A real, live PhD at SMC...that's impressive!

[george wilson]

You need to inform Fine Woodworking magazine so they will stop spreading false info about turning spalted wood.

[Seri Robinson]

You need to inform Fine Woodworking magazine so they will stop spreading false info about turning spalted wood.

Where do you see the 'false information'? I do all the current spalting writing for Fine Woodworking, so all their information is up-to-date in terms of current pathology data. If you could send me a link, I'll look into it.

[Prashun Patel]

Oooh, George! Now you've stepped in it!!!

[george wilson]

I really can't recall. It was many years ago.

[Seri Robinson]

I really can't recall. It was many years ago.

Ahh, well that solves it then. The original stuff published by FWW on spalting did talk about the 'dangers' of the spalting fungi. Rest assured, that's all been debunked, and they no longer push these myths. Some of the other magazines, however...

[Prashun Patel]

Here's the slab I'll be using. I wonder what kind of fungus that green spot is from ;)

[Prashun Patel]

My go-to finish is usually oil/varnish. I think I might shellac this chair, though. I saw some shellacked chairs at a show a few weeks ago, and it felt so nice. Also, been itchin' to spray again.

Anyway, my q is regarding how to harden any soft spots. I'm planning to inject some CA glue into a couple patches. But should I do this before, in the middle of, or after I shellac? I'm planning on using Garnet.

My instinct is CA first, and that it won't hurt the color.

[Prashun Patel]

I finished rough carving the seat blank. This is an experiment. Not sure how it'll even look....

[Seri Robinson]

CA glue before you shellac. The shellac will then help even out any color change.

CA glue is your best bet for spot hardening of spalted wood if you're using a penetrative finish. You could skip the whole mess though if you just used a top-coat water based.

[Dennis Lopeman]

I liked that first link to the Baur Stool... cool look - looks like a butt-splitter thought!! HAHA...

ok - that's all I had... if anything I just like to make jokes... a lot.......

[Cody Colston]

Shawn, that chair is gonna look spectacular. I'd build it just too look at, even if it was too weak to sit in. :D

+1 on CA glue for small soft/punky areas. The thin CA will really soak in, too.

You could also consider Minwax wood hardener for large areas or maybe even the entire seat. It's about the viscosity of water and will soak in just like the thin CA. I use it, as do many turners, on lathe pieces that are punky. I'd check it on a test piece first, though and see how it looks under shellac.

[Prashun Patel]

This has been an interesting experience.

All the joining and crude shaping is complete. Now comes the fun/hard part: sculpting. The last time I did this, I used handtools for about 90% of the work. I'm trying to use the grinder and ROS as much as possible on this one. That's really the only way to be able to do this multiple times.

Carving spalted wood is very difficult. Soft areas tend to machine like soft pine. So, getting smooth flowing lines is hard with aggressive tools like grinders or rough rasps.

I'm going to try to harden some of the soft areas before final shaping.

Live and learn, yo!

[Cody Colston]

That chair is gonna look awesome! You are working very fast, too.

I can hardly wait to see it with finish on it.

[Prashun Patel]

Coty-you know that 90% of the work is the sculpting and finishing!!!
I also took a shortcut: I didn't roundover the leg joints. I squared off the mortises with a chisel instead. I wanted to test how it looks on this 'prototype' chair...

[Prashun Patel]

Finished.
http://www.sawmillcreek.org/showthread.php?t=140877&highlight=spalted+maple+chair