Overly spalted / slightly rotten wood?

[Charlie Harley]

Is there something that can be done to harden wood that is slightly soft from being overly spalted or slightly rotten?

I have a piece of walnut that came from a firewood pile. It's very pretty and 95% of the wood is solid, but there are soft spots that I'm worried about.

Any suggestions?

 

[Griesbach]

Charlie, although I've not tried it I've read where a lot of folks have soaked the rough turned piece in a 50/50 mix of white glue and water. I would imagine that the soak time varies by the condition of the wood and then let it dry again.

I'm sure others with experience will chime in.

 

[John Abt]

I've used very thin CA and let it wick in.

 

[n7bsn]

Minwax Wood Petrifier works, but it doesn't penetrate as deep as I would like and I have to re-apply it.

 

[S. Clark]

There is an epoxy hardener called Restore-it that I have used extensively in remodeling and restoration work on old buildings. I have been quite pleased with it and keep meaning to try it on a punky turning blank. You might like to try it. The manufacturer calls it a “clear penetrating epoxy sealer†specifically designed to “harden decomposed wood fiber and seals to protect against further damageâ€Â.

 

[MichaelMouse]

Is there something that can be done to harden wood that is slightly soft from being overly spalted or slightly rotten?

I have a piece of walnut that came from a firewood pile. It's very pretty and 95% of the wood is solid, but there are soft spots that I'm worried about.

Any suggestions?

Chose your tools carefully, and your cutting angles as well. You want to avoid cutting uphill against unsupported fiber, especially where the fiber has lost what connected it to the other fibers in the first place. I'll stick with the idea of a broad-radius gouge, skewed back from the lead point of the cut to make the final separation feathered almost to nothing. Bridges small soft spots pretty well, and hugging the rest rather than "riding" the bevel pays double dividends in this case by not diving from hard to soft and not making ugly crushed spots where you pressed too hard either to stabilize the tool or to tilt and change direction on the cut.

Real fun comes when sanding, and my answer is the same, hug the rest to keep the sander stable as the lathe rotates and don't press. Stiffer configuration on the disks, if you can use them, is a big help. Then, when you do go to work-supported sanding, do so only at the finest grits, with the broadest disks to span over soft spots, or sand from the firm wood no more than halfway into them as if you were sanding an irregular edge.

If you decide to stiffen things with resin, and I'll call polyvinyl acetate the same as, be sure and use stearated paper. Open coat and a bit of lube will keep stuff from gumming things up. Since things like PVA flow when heated, the lube will help you there, too. Malodorous mixtures using other resins are also possible. The one closest at hand for most of us is CA, which is my preference, but does pretty much limit you to a mechanical bond finish if you expect things to look even.

 

[john lucas]

I use lacquer thinned 50/50 with lacquer thinner. It penetrates the wood really well. I let it hardern overnight but smaller areas will usually harden in a very short while. It does gum up the sandpaper but I keep a wire file card handy and just clean up the sanding disc when it starts to clog.
I use lacquer as a finish so I don't have to worry about over run marks or whether or not the finishes will be compatible with the hardner.

 

[Ruth Niles]

Charlie, I use the 50/50 glue/water, I use Tite Bond II and it works just fine. The soak time probably does vary but I usually work on something else while it's soaking so it could sit for 2 hrs. to 2 days. I just let it dry, the wood will only soak up the solution until it's saturated. If there's only a small area that needs it, I'll just keep brushing it on liberally until I can see it's not absorbing anymore then let it dry. It sands perfectly, just like the wood and drys clear so you can't notice any difference in texture.

 

[Gretch Flo]

Charlie, I use the 50/50 glue/water, I use Tite Bond II and it works just fine. The soak time probably does vary but I usually work on something else while it's soaking so it could sit for 2 hrs. to 2 days. I just let it dry, the wood will only soak up the solution until it's saturated. If there's only a small area that needs it, I'll just keep brushing it on liberally until I can see it's not absorbing anymore then let it dry. It sands perfectly, just like the wood and drys clear so you can't notice any difference in texture.

Ruth-Will it absorb an oil stain symetric with the other wood??? Gretch

 

[Ruth Niles]

Gretch, I've never used it with any stains. The only wood I've found it necessary, or that was worth the time, is the well spalted and I don't stain them. I've never noticed any color variation when I apply the oil finish. I think with soaking it to its saturation point, then sanding, you'd be virtually staining the glue/water mixture with the wood so I doubt there be any problem.

hmmm, guess I'll have to try it.

 

[Al Neighbors]

Just a guess, but

I think the glue/water mixture will inhibit the absorption of stain. You may have to use waterbased stains, and put it into the glue solution before hand.
I don't use stains, either, but when you wipe glue squeeze-out from a glue joint, stain won't penetrate that area once covered by the glue.
Hope this helps.
Al

 

[Andy Coates]

curing soft spalt

Hello there,

here in the UK a common cure for soft areas of spalt is to apply a generous coating of sanding sealer and allow it to dry. It really firms up the soft areas without causing the wood to accept finish poorly. Most of the treated wood is actually cut away so you achieve what you want; the wood firmed enough to allow a clean cut prior to abrading and finishing. Do be aware though, that abrading should be done very carefully as you may abrade dips and hollows on formally soft areas.

Another tip commonly used here is to thin the sanding sealer down with cellulose thinners, 50/50 is fine, which allows better penetration into the soft wood.

Hope this helps

Andy

 

[MichaelMouse]

Common language again. You say "cellulose thinners," which to me means you're using a lacquer-based sanding sealer. As mentioned above, shellac-based "spirit" sealers are also common here, and home mixes can be easily metered for fill capability as well.

Nowhere here has anyone mentioned something very important, which is that it's generally a waste of time to do anything like this until your material is dry and ready for the final passes. Don't know if we expect that to be common knowledge or not, but even our common language can confound, so I mention it.