Brown Rot, White Rot and other Wood Pestilence.

[Bob Smalser]

Bob,
Punky wood...is that the stuff that isn't really rotted yet, but it's on it's way? Dark, even black, solid but a little soft, hard to dry out. I wonder if my floors and keel are punky at this point? How does one define it?


Grow, mill and airdry enough lumber, plus restore several old boats and you eventually get to see it all, so I’ve saved some examples of pest damage to show you what’s what, what’s bad, what’s not, what you can do about it, and some why’s and wherefores. I’ll start with the worst, and end with the worst.

Brown Rot

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438312.jpg

Often called “dry rot”, but there’s nothing dry about the results of this fungus attack that consumes both the cellulose that provides wood fibers their strength and the lignin that holds those fibers together. Brown Rot leaves some lignin residue that creates the distinctive cube pattern associated with this rot. Like all fungus, the spores of these species are everywhere in the environment, but they need warmth, oxygen, moisture and food to germinate and grow. Alter those conditions to inhibit it.

Temperature. Between 75 and 90 degrees F are ideal, and below or above that range germination tapers off on a linear scale until 40 or 105 degrees where it stops entirely. Where I am, 55 degrees and lower stops significant fungus activity in wood. High temperatures kill fungus entirely, which is one reason for kilning wood to the international standard of “56/30” or 56 degrees C for 30 minutes.

Oxygen. While oxygen is required, significant airflow deters spores from gaining a foothold, so ventilation is useful in prevention.

Moisture. Like all organisms, these need water, and 20% moisture content is their threshold. That’s another reason why construction lumber for domestic consumption is generally kilned to 19% – to prevent the stains and worse damage caused by fungus. Kilning to the 56/30 international standard for a “KD-HT” (heat treated) stamp also coincides nicely with the domestic “KD-19” (kiln dried 19%) stamp. “HT” wood here runs around 16% MC, which is adequately dry for immediate exterior or marine use without the danger of overkilning damage.

Food. While the species that cause Brown Rot eat any cellulose, most other fungus prefer the sugars found in sapwood, where most problems begin. Saturating or coating wood with preservatives like copper and lead poison their food to prevent growth, as do the natural extractives found in the heartwood of durable species. Extractive is a 5-dollar word describing the concentration of salts, colorful resins and acids that occur as the cells of sopping-wet, weak, sugar-laden sapwood transition to the relatively-dry, tough, heartwood that provides the tree’s stem its strength.

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438316.jpg

Because it consumes both cellulose and lignin and is self-generating, Brown Rot causes severe damage quickly if left unchecked. Here you see that planing the surface didn’t remove the rot pockets, which remain discolored and spongy. If I were to plane off a little more surface, I’d arrive at wood merely discolored. This is called “incipient rot” because the fungus species causing the discoloration are still there waiting for the right conditions to grow again.

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438629.jpg

Brown Rot is self-generating because removal of cellulose combined with lignin damage creates a sponginess that is hygroscopic as well as structurally unsound. Here you see the rotted area of this old cedar fence post is at 29% MC on the “A” Scale of my moisture meter….

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438623.jpg

…while the sound wood only a few inches above the rot is only at 16% MC on the “B” Scale, well below the 20% threshold for fungal growth, and a huge difference in moisture between sound and rotten. But not for long if that post is left intact and outdoors, because the wet area full of wood-destroying fungus will grow. A good moisture meter with pin electrodes can easily help you find hidden pockets of rot when surveying a boat. Just carry a small tube of 3M 5200 to fix the holes when you are done.

http://pic20.picturetrail.com/VOL12/1104763/6771586/89185165.jpg

What to do when you find the soft wood that indicates rot? Remove it all the way back to good wood and replace or repair it. Brown Rot is almost always deeper than your first assessment:

http://pic20.picturetrail.com/VOL12/1104763/6771586/104804800.jpg

Continued….

[Bob Smalser]

http://pic20.picturetrail.com/VOL12/1104763/6771586/109016867.jpg

When excavation reaches the incipient stage of only discoloration of otherwise sound wood, CPES (an epoxy sealer) may be useful to isolate the remaining spores and reduce the wood’s potential to absorb moisture prior to replacing the structure lost to the rot.

White Rot

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438142.jpg

Sometimes called “slime” or “wet” rot, the fungus species responsible for White Rot are most often found in non-durable hardwoods where they cause spalting. Here you see large patches of White Rot in a sea of Blue Mold. White Rot also consumes both cellulose and lignin, consuming the lignin completely and bleaching out the wood’s color.

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438141.jpg

Like all fungi, tendrils or hyphae spread the fungus to areas favorable for its growth, these sufficiently large to be obvious.

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438313.jpg

When they attack softwoods like the Douglas Fir shown here, they don’t seem to penetrate as deeply or as quickly as does Brown Rot and can often be planed off to no ill affect to the use of the wood.

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438634.jpg

Incipient White Rot on a sapwood edge of roughcut Douglas Fir 2X stock.

Soft Rot

http://pic20.picturetrail.com/VOL12/1104763/18169354/285540065.jpg

Soft Rot is caused by another group of fungus species and is generally found in wood with sustained high levels of moisture such as telephone poles and other buried posts immediately above ground level, and in water tanks. The entire surface of the wood becomes punky and can be lifted off in sheets. While I think keels and floors awash in bilge water would be susceptible, in boats it's often found in areas of high surface to thickness ratios such as plywood.

Continued….

[Bob Smalser]

Lichens

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438639.jpg

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438637.jpg

Interesting and sometimes colorful little algae-fungus combinations that are generally harmless and can be brushed off.

Blue Mold and Ambrosia Beetles

You’ll find Blue Mold (or Blue Stain) without Ambrosia Beetles but you’ll rarely find Ambrosia Beetles without the stain. Various species of molds and sapwood stains feed off the moist sugars in sapwood and discolor it in the process, often permanently.

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438143.jpg

Here you can see bluish discoloration in the sapwood edge of a Douglas Fir joist. As the joist was recently scrubbed with full-strength bleach, the stain is permanent. You can also see a few bluish pin holes in the sapwood from Ambrosia Beetles. These insects attack stacked logs and downed trees still having intact bark throughout the warm months of the year within as short a period as two weeks. The adult beetles bore through the bark into the wet sapwood, lay their eggs in the tunnels, and depart. Their secretions plus the sugar in the sapwood attracts Blue Mold development in the tunnels, which their larvae feed on after they hatch and also eventually exit the log to continue the cycle. In some woods the result is considered attractive, and there is a market for “Ambrosia Maple” as one example. Prevention measures include milling immediately in summer, debarking or ponding logs waiting to be milled, including continuous irrigation of the log stacks with water, which also inhibits other fungi due to oxygen depletion. They cause little real damage and are no further threat once Ambrosia affected wood is seasoned.

Carpenter Ants

Carpenter ants come in small and large sizes and also don’t eat wood, but use it for nesting. They require warmth and nearby food – remove one or both to drive them away.

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438145.jpg

The tiny species don’t have big munchers and seem to only attack wood already softened by fungus, here where a sapwood sticker in a board stack rotted and was attacked by the ants. The photo is of the mostly heartwood board beneath it and you can see where the ants attempted to bore, but only succeeded in a small area of sapwood. These aren’t a big problem here, and the damage can be planed off.

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438144.jpg

The large species are incredibly tough, can chew their way through almost anything, and here prefer to nest in the pith areas of live cedar trees, often forming centuries-old colonies of vast numbers. In the lumber yard, they usually don’t attack stickered stock through around 4X thickness, because there isn’t enough protection from the cold in relatively thin boards. They don’t usually attack stickered 4X and 6X beams like the one shown either, but if you are sufficiently absentminded to restack them touching each other after grading, you provide 8-12X of insulation and a perfect entry point for the ants. When they infest the wood or insulation in your house, what they are attracted to is the warmth. Sprinkle a persistent insecticide like Diazinon around the outside foundation of your house and beneath your lumber stacks when the temperature reaches 55 degrees in the spring.

Powder Post Beetles

http://pic20.picturetrail.com/VOL12/1104763/18169354/285438315.jpg

A much more serious pest, the various species of Powder Post (or Furniture) Beetles eat the starch contained in wood instead of just nest in it, and penetrate throughout the heartwood as well as the sapwood. They are common in barn timbers, old furniture once stored in barns, and hardwood stacks overgrown with vegetation that inhibits air flow. One variety even penetrates hard varnish finishes to get to the wood beneath. There are various home remedies of fuming and borates but none are 100% reliable. To eliminate every stage of the beetle, infested wood must be kilned per the “KD-HT” schedule previously discussed.

Preventions are usually easier than cures, but knowing which pests are fatal and which are merely cosmetic helps you pick your battles.

Reference: A.J. Panshin and Carl de Zeeuw, Textbook of Wood Technology 3rd Ed, McGraw-Hill 1970.

[Hughman]

Well done! :)

thanks!

[Ian Marchuk]

Great stuff , Bob , thank you....
Best Wishes.... Ian

[Jay Greer]

My old pappy once said,"If it weren't for all the forms of fungus and wood boring critters, the world would be ten feet deep in wood." Not much consolation when your boat is the infected one!
Thanks for the in depth study!
Jay

[michigangeorge]

Consise and easy to understand, thanks Bob.

[Bill R]

Thank you Mr. Smalser!

[dmede]

Thanks for another great essay. The carpenter ant info is particularly interesting since thats what I think I've been seeing in my WRC. Actually found one of the ants as I was milling the other day. He seemed to be long dead and dried up.

[Bob Smalser]

Black Sawdust




One of my finest logs of WRC was 20+ rings to the inch, 72" DBH, clear as a bell and 30' long...not a hole or degrade visible on either end...couldn't wait to get into it...prime boat planking.

Bucked the lower log at 12' and set the big swing-blade mill up atop it, as it was too big to move safely with the old farm tractor I was skidding with at the time. Didn't test it for rot with plunge cuts with the big Stihl, as that wastes prime wood whether you were right about the rot or not.

I get half way thru the opening vertical cut, and the forces on the saw lighten up...I continue cutting...probably a pitch pocket or patch of softer sapwood. Then the saw on the return horizontal cut begins to spit out black sawdust, getting down my shirt and trousers as usual. No big deal...that's why God gave us that after-work shower bath.

At the end of the cut I pull away the slab, and a gazillion carpenter ants swarm out all over me.

I musta looked pretty silly stripping down to full nakedness in that open wood lot within sight of the road.

[Thorne]

Another great web essay/article, wonderful photos, and a BIG help to all us builders.

Thanks!

[Woodonwater]

Thanks Bob!

This post is one for the thread 'book' that is sort of assembled at the top of the forum.

James

[Peter Malcolm Jardine]

Bob, a couple of questions for you. Does a moisture meter really tell whats going on in a wooden boat hull? I would have thought that below the waterline, the moisture content would stay fairly linear if the boat had just been pulled from the water. (freshwater say). As the boat dries out, wouldn't moisture content start to vary depending on where frames are, and butt blocks? My interest here is in my own boat, which a surveyor who I deemed to be very inexperienced with wooden boats brought a moisture meter. On the places she labelled as suspect, I checked both inside and out, and could not find any soft wood whatsoever. Topsides, butt blocks behind planks are a common place to find rot in my experience, as well as sheer planks that get water coming in on their edge, rotting from the deckline down. Any further comments would be appreciated.

[Bob Smalser]

Does a moisture meter really tell whats going on in a wooden boat hull?

I would have thought that below the waterline, the moisture content would stay fairly linear if the boat had just been pulled from the water. (freshwater say). As the boat dries out, wouldn't moisture content start to vary depending on where frames are, and butt blocks?

Yes, it does....if you have a baseline to compare it against. That means either a booklet full of data on readings by thickness and species you've taken off other boats locally or what you collected on your own boat last time it was hauled. Lack of same is directly proportional to the guesswork required to make an assessment and its lack of accuracy.

MC on my moored, 4/4 and 5/4 cedar hulls generally run 6-14% above the waterline depending on time of year, 16% or so below the waterline but above the bilge water, and 19-22% below the standing bilge water. These are work boats with indifferent paint and care allowed to bake in the summer and fill with rainwater in the winter, and should be considered extreme MC ranges compared to most yachts.

My WRC hull runs 2 or more points drier than my POC hull, because POC is denser and generally the denser the wood, the higher the MC. Frames, buttblocks, thwarts, have almost no affect at all on the moisture content of the planking....but mine are all Doug Fir at a similar MC. If they were denser oak at a higher MC, they might serve to make the cedar planking attached to them slightly wetter at the faying surface, but I suspect you're barely be able to see it even on the best meters. Where you see a big difference is like my rainsoaked fencepost above....29% for the rotten and 16% for the sound.

[Peter Malcolm Jardine]

One addendum... My Chris is double planked, mahogany over fir ply. Some of the moisture contents were higher than 16% after a winter out of the water. I checked areas where I could get to on the inside, and really checked the outside areas. Couldn't find a darn thing, and no evidence of cupping or fasteners being loose. Could it be the plywood? Some areas I couldn't get to because of interior panelling etc.

[Bob Smalser]

My Chris is double planked, mahogany over fir ply. Some of the moisture contents were higher than 16% after a winter out of the water.

By winter you mean 4 months of low-humidity ice and snow or 4 months of 35 degrees and slush? During our 6 months of 35-40 degree temps and rain boats out of the water don't dry at all. 12-16% may be normal.

[Peter Malcolm Jardine]

By the time this was done, and judging that winter, We only get about a month or two of cold weather... then it's wet and 35 degrees. I guess my query is why the differences... and of course by this time the boat was uncovered, and some rain had fallen... even trickled some into the lower bilges. The boat comes out in October, and goes in by May.
Oh, and I had washed it down completely and thoroughly too.

[Bob Smalser]

Your boat isn't drying at all over the winter. And by definition, a rot pocket is at 20% MC or higher, or it wouldn't be rotting.

[keck314]

Bob,

Is there any way to tell if these critters are still alive? I have a 200 year-old board that I'd like to make into some seats. It's clearly been home to some carpernter ants and powder-post beetles at some point in its history, but I don't know when. I was planning to simply seal all the holes with thickened epoxy. If any of them are still alive, though, it sounds as though this might not be sufficient. Is that the case?

[Bob Smalser]

Bob,

Is that the case?

Yes.

The only thing you can do if you don't want to take it to a kiln is set the board in one spot for a year and look for the frass (sawdust) that indicates there is still beetle activity.

[FSS172]

Bob - For one board, how about fumigating - seal it up in plastic with some sort of insecticide. Could consult an exterminator for the best poison for the job - preferably something that would not leave residual nasty stuff - maybe even have them do it. What do you think...

[J P]

keck314, you might try wrapping your board in black plastic and cooking it in the sun.

[Bob Smalser]

Bob - For one board, how about fumigating - seal it up in plastic with some sort of insecticide. Could consult an exterminator for the best poison for the job - preferably something that would not leave residual nasty stuff - maybe even have them do it. What do you think...
Mama Nature designed those beetle eggs to be incredibly tough, even without being protected by whatever thickness of hardwood you're trying to penetrate.

If you can get the core of the wood to 130 degrees for the duration of a hot, sunny afternoon by tenting it in black plastic, then give it a try. You can also try fumigation by tenting the wood with a bowl of insecticide evaporating on a heater for a couple weeks, but last time I did that we had stronger insecticides. But as I said, only thorough heat is 100% reliable. Those beetles may be long gone. Or they may not be. Any method short of the prescribed heating schedule means you'll have to accept some risk.

[neilm]

Bob, You should publish all your posts in a book. Your info is always more detailed than any boat building book I've read. Great stuff! Thanks.

One question I have is what are the drawbacks to using Copper and Lead based preservatives? Are there any health risks if painted over? What about sanding/refinishing down the road? Also, isn't Red Lead outlawed? I can't seem to find it.

Neil

[Bob Smalser]

Just avoid eating lead and copper paint by sanding it without wearing a respirator, and I don't believe either are a health hazard to adults. I only use lead as a primer protected by paint and I don't use ablative copper in my fresh water ponds because they are more smaller and sensitive than seawater, where I would use copper.

Kirby's and Sandusky both sell red lead paint, and fireworks suppliers sell lead tetraoxide powder with which you can make your own primer. A gallon of 50-50 BLO-turps, a half cup of Japan Drier and 3lbs of lead tetraoxide makes an excellent primer for alkyd paints.

http://www.skylighter.com

[pipefitter]

Here in Florida,bug capital of the country,it was hard to keep wood bits free from termites and such. I have an old Cushman maple table I did a ceiling patch for and it came from a wood frame house and there was visible termite damage. Not wanting to bring the critters into my home,I called the local termite company and they included it in a Realtor home they tented with Bromide gas. He assured me everything and anything in the wood would be dead. I am not sure if the beetles mentioned are safe from bromide gas but you may be able to get a fumigator to include it for a few dollars or to fumigate it independently.

[Bob Smalser]

Like chlordane and the parathions, methyl bromide fumigant is one of those pest control agents no longer available. It depletes ozone.

[keck314]

The wood I have is 1"x16" - it was originally a wall panel in a house that was built around 1805 and collapsed in the early 1970s. Both the carpenter ant damage and the beetle exit holes are confined to the unpainted, inner face of the board. I ripped the wood in two this evening, so I was able to see some of the beetle burrows in cross section - they all penetrate roughly halfway through to the other side (0.5"), and when I cut the seats to length, I can probably avoid some (though not all) of the most damaged areas.

The face-preferential distribution of insect damage would appear to argue for it having occured when the board was still part of the house - thirty years ago at the latest. The board has since been in storage where it seems to me that both faces would have been vulnerable to attack.

That said...how much does it typically cost to throw wood into a kiln? Does anyone know of one in the D.C. area? Maybe I could befriend someone with a commercial bread oven, though I imagine that would run afoul of some kind of health ordinance :P

[Bob Smalser]

http://www.woodweb.com/knowledge_base/Beetle_Troubles.html


Question

I have a 6' x 7' door in one of my shops. It is poplar, sawn about 12 to 15 years ago. You could sweep up a gallon of powder sawdust under it and it is full of little holes. What should I do with it?

From Professor Gene Wengert, forum technical advisor:
Sounds like the lyctid powder post beetle, which can easily spread to other hardwoods. You need to get the door out of the shop ASAP. Then vacuum up any dust or debris and hope that the insect has not spread. Move the collected dust out of the shop. It sometimes takes a year or more for the eggs to hatch. If you heat the door to 135 F, it will kill the insects and eggs, but the door may already be ruined due to all the holes.

Some say a methyl-bromide or Vicane fumigation will solve your problem. It may but only in raw large pore wood. Wood with a tight cell structure will resist this treatment. Also any finished wood will can't be treated this way. Heat treatment is the only way to stop a finished piece infestation. Do this carefully as thermo-shock can result in popped joints depending on the glue used. Bring the temp up easy and let it down easy. 6 hours including a 1 hour ramp up from 70 degrees and a 1 hour cool down will bring the core of a 4x4 piece of white Oak to 135 degrees.

From contributor M:

I had powder post beetles in some beams I cut and I wrapped them in black plastic and laid them in the sun in June for 3 days. The temperature outside was 95 and inside the plastic on the shady side was 145. The beams were very warm to the touch. I coated the beams with a heavy dose of Durasban (spelling?) and re-stickered under tin. Have not seen any new powder under them. They were 6x6x18' white oak and I did not want to move them much.

From contributor M:
We are getting fewer hours of sunlight than in July. You might want to increase the heat potential by:

1. Wrapping the clear plastic around the black material leaving an air space (greenhouse effect).

2: Using a dull black material around the beam, as shiny black plastic will reflect some of the heat/light away.

3: Placing an electric heater inside, under the beam (but not too close!).

From the original questioner:
It turns out that poison injection is not practical because, as I rework the beams, I'm finding lots of little holes, almost always in the red oak. I'm going to have to try the plastic and sun route. I will leave them out for a fair length of time.

From contributor M:
If you've got that many bug holes it is probably black oak, which is a variety of red oak that bugs just love.

Heat (over 130 F for 24 hours or more is required) is very effective in killing the eggs and the insects. After the insects lay their eggs, it may be up to two years before they hatch, so be careful about an inspection that shows no further damage--there can be more in a while.

Are the holes about 1/8 inch or larger in diameter? If so, then it is a common anobiid powderpost beetle which does not like dry wood, so the problem will disappear. Of course, the insects are in the air-drying yard, and will infect other lumber that is there. This is why some treatments (such as CO2) appear to work to kill insects -- in truth, however, the insects are eliminated by the dry wood, not the gas.

Gene Wengert, forum moderator:

It would take over two years of gassing to kill the lyctid powderpost beetle and its eggs, as the eggs may require two years to hatch. Lack of oxygen does not kill the eggs!

If the holes are smaller, then you may have the lyctid powderpost beetle, which indeed can cause substantial problems, even in dry wood.

A temperature of 130 degrees F will kill all insects, eggs, and fungi. It takes about 24 hours in most cases (this is the temperature in the wood).



Powderpost Beetles in Furniture
Pinholes and powder are a dead giveaway of a beetle infestation. Here are some facts about the bugs and how to handle them. February 19, 2006

Question
A customer has found a few pin holes in a piece of red oak in one of my chairs. She claims they have always been there, but she has just noticed they seem to be generating some fine saw dust. They apparently are mainly in the early growth rings but I am waiting for her to ship the piece (a bench via UPS) back to me.

I have not had any problems with red oak or any other wood in my shop or any other customer having problems. What are they? What treatment can I use? The finish is Watco Danish Natural Oil and paste wax. The piece only has the critters in stretchers from the same dowel and there is nothing in the legs or the other two stretchers.

Forum Responses
(Furniture Making Forum)
From contributor H:
Most likely the wood was only air dried. Those critters can lay dormant for years. Getting rid of them is easy. Get rid of the piece they’re in before they spread.

From contributor S:
These beetles are usually found in green wood and die when the material is kiln dried. If the material has the beetles in it already they can spread rather quickly to the rest of the piece. I do not know of any way to get rid of them once a piece is built.

From Gene Wengert, forum technical advisor:
Let me correct some of the information provided: There are different types of powder post beetles. You are dealing with lyctid PPB. This insect prefers drier wood, down to 8% MC. Other PPBs like wetter wood. It is typical to get this beetle after kiln drying, not in green wood or in air dried wood.

The PPB in furniture cannot be controlled with chemicals, as the insect is deep within the wood and any chemicals stay at or near the surface.

It is difficult in a piece of furniture for them to leave the wood and for "Ma and Pa" to find each other, breed, find a grainy wood to lay eggs, etc. So, you do not have to worry much about spreading, but the home-owner may not accept this. Of more concern is the damage (strength loss) done to the wood.

All wood that is kiln dried above 130 F is free of PPB and their eggs. So, it is likely that the infection developed when your wood was exposed to other infected lumber after kiln drying. In fact, you do have a risk that it will show up elsewhere in the next year. Springtime is the most common time. Your lumber supplier is probably the source and you may wish to consider changing suppliers. If they have the infection, it will likely continue to show up in the future.

They will remain active for several years. They will not re-infect wood with a smooth finish (varnish, etc.) but can do a lot of damage in the pieces where they are present. It should be removed from the house as soon as possible. It needs to be replaced. Keep the infected pieces and furniture away from all other wood, especially unfinished wood or lumber. Heating the piece (or lumber) to 130 F for a day will kiln the insects and their eggs. It is not uncommon for insects to show up a year after infection.

.


Treating Air-Dried Wood with Pesticides


From Gene Wengert, forum technical advisor:

Any insects in the wood will not be affected by putting a solution of borax on the wood and treating the surface. Borax is intended for green wood, not 20% MC. As mentioned, you will not affect the insects inside the wood, so borax is a waste of time at this point, especially if you want to control the ones that are nibbling already. You cannot rewet the sapwood enough to get the borax inside the wood and not harm the wood.

Further, rewetting dry wood like you have will cause the surface to swell rapidly and can actually pull the inside apart (creating honeycomb). Therefore, one of the primary rules for drying is never rewet partially dried lumber.

As you are going to use the raw edges, I wonder if residual borax in the wood would affect the finishing. Unlike other approved insecticides used on wood when the wood is green, borax lasts for a very long time. I also wonder if borax will discolor the walnut wood.

To heat the wood to 130 F and destroy the insects would be fairly easy. Rent a trailer or a small truck with a separate cargo area, and put the wood inside. Then get a heater and heat the wood to 130. Of course, fire issues mean you will have to be very careful with the heater... maybe keep the heater outside and just push the heated air into the chamber. Think about the safety issues carefully ahead of time.

[keck314]

Update: Dad (FSS172) and I have decided that when I go home in a few weeks we're going to roast them under a couple kilowatts of theatrical lighting at close range. Ought to do the trick.

[Excalibur]

Hi Bob, a question...

You wrote (about Soft Rot):



While I think keels and floors awash in bilge water would be susceptible, in boats it's often found in areas of high surface to thickness ratios such as plywood.



My boat has a constantly wet bilge from salt water. Do I have special wood rot concerns, or does the fact that the water is salty mean I'm generally Ok?

[Bob Smalser]

Wood bathed in salt water is hardly immune, but doesn't seem to be as vulnerable as that in fresh water, especially rainwater ingress.

I think the single biggest factors are the quality and seasoning of the wood and the quality of the construction. In my plywood example the shop that built it used good plywood, but took all manner of shortcuts in joinery, bedding, and drainage that no wood would easily survive over the course of decades.

[Excalibur]

Thanks, Bob.

My old Chris lives under a covered slip. The good is that I have very little worries about fresh water intrusion. The bad is that sunlight doesn't intrude too much either! I'll keep an eye on the bilge, and continue on working to keep the water out. I'll need to pretty much totally rebuild my rudders to do that tho, their mounts are really corroded and appear to be original '66 hardware... My current winter project is cutting up the sole to create nice large openings to allow good bilge access.