Sanitize a Bowl After Turning

[Ross Berning]

While turning some spatled maple I noticed powdered post beetle holes on the bowl exterior on one side only. Figuring the critters would not have a resistance to HSS I finished the bowl down to about a 1/8 wall thickness. The bowl is now in a plastic bag while I debate what to do with it. The holes are about even in number inside and outside but hard to count.

All the advice I’ve seen is on sterilizing blanks not a bowl with a fraction of the overall size. So far I’ve microwaved the bowl for two minutes and put it on the dash of the car in the sun, where temps got into the 110° for a couple of hours and 136° for an hour or so. Based on a twenty year old UW extension page I may try temperature shock - quickly going from very hot to the freezer.

Many of you are saying ‘throw it out’ but it’s an interesting problem to solve. It may just live in a bag long term as an experiment. What else should I try?

 

[Brian Gustin]

if you can see clear through all the holes, there ain't no bugs in them, so I'd be much more interested in sterilizing the wood waste (shovel it out and burn it quick) before any remaining bugs start in on th woodwork and structure of the shop!

 

[John K Jordan]

Only worry about the PPBs if you have holes visible on one surface and not on another. Frass (fine power) on a surface, is a sign of active beetles. After a few years eating their way through a large piece of wood they exit and don't come back. There are several types and I understand most only go for tasty, wet wood. Surface treatment to prevent infestation is effective but heat is recommended for bugs in the wood. Can't remember the temperatures or times - seems like it might be about 130F held for several hours, enough for the heat to penetrate to the inside. I'd check the wood web.

If the wood is old an you see no sign of frass where it was stored, chances are the bugs are long gone. If the holes are darkened around the edges it's a sign they are long gone. I have a supply of wormy American Chestnut

I've turned wood with lots of PPB holes and never cut into one. As mentioned, if you can see light, there is no beetle. I have cut into and through plenty of larger grubs though, in green wood! They are often under the bark in wood that has been on the ground.

Seeing a live PPB is rare. I had two unique experiences - I once watched a "swarm" of PPBs fly towards me from the woods and started landing on the end grain of some maple I was processing outside of my garage door, obviously attracted by the smell - when landing, they immediately started chewing into the end grain, some even through a coat of Anchorseal! I quickly sprayed the surfaces and bugs with insect killer and took the wood insde.

An about 20 years ago I saw one exit the wood! A friend gave me a bundle of 24" 2x2 walnut squares that had been stored outside and I stacked them on a shelf in my little shop. In a rare quiet moment I heard a soft "scritch, scritch, scritch" sound behind me and while searching for the source I actually watched a PPB chew through the end grain and start to exit the wood! What are the chances! There was no visible frass I grabbed the bundle and took it outside.

Sawmills sometimes use Boracare to prevent infestation of freshly cut wood intended for air drying. Kiln drying kills any beetles.

JKJ

 

[Richard Coers]

The holes are the exit holes, they are an indicator of where adults left. They are not an indicator of how many eggs or larvae are left in the wood. The only heat that makes a difference is getting the entire piece over 133 for at least an hour, all the way to the center. The freezer does nothing. I would be just as worried about slinging larvae or adults around your shop when you turned the bowl.

 

[robo hippy]

I chase those holes with the thin CA glue. Don't know of any other 100% cure other than the glue. It will penetrate all the way down in, and no accelerator!

robo hippy

 

[Kirk Amidon]

Put it in a cold oven, turn on to ~175-200 degrees, and once up to temp let it ride for 2 hours or so. Turn off oven, let slowly cool back down.

This technique may require additional expense of a spa trip or sponsoring another such outing for your significant other - no warranty that this won't cause strife...

 

[Kent Reisdorph]

I just ignore all holes. Occasionally I will see a live grub (not PPB). Dig 'em out and keep turning.

 

[Richard Coers]

No idea why it took me so long to post this picture based on Ross' title. Another sanitized bowl.

 

[Richard Coers]

I just ignore all holes. Occasionally I will see a live grub (not PPB). Dig 'em out and keep turning.

A PPB infestation is not something you ever want. Hiding your head in the sand and ignoring the possibility will seriously bite you someday! Especially if you sell a bowl with bugs in it, and the customer insists on you paying for a tenting and fumigation of their home. That bowl will cost you about $35,000

 

[Brian Gustin]

I just ignore all holes. Occasionally I will see a live grub (not PPB). Dig 'em out and keep turning.

If you see holes like the ones in the original post, you definitely DO NOT want to ignore them. We learned that lesson the hard way after a friend crafted some book cases out of leftover construction lumber (1x10 pine) and left them unfinished. in about 6 months we started seeing little frass piles by which time they had already infested Jean's (my wife) $1200 antique armoire (her grandmother's) Everything was quickly taken out of the room and room sealed & fumigated, we lost several dozen books, the armoire damaged beyond repair, and the book cases full of holes everywhere. Ended up burning all the book cases and armoire, and I made a new set of book cases and applied finish. PPB are very happy to invade any unfinished exposed wood, we found, whether it is wet or kiln dried. Since then I have been rather paranoid about PPB and if I even SUSPECT a wooden item has had PPB in it, it goes straight to the burn barrel.

 

[Ross Berning]

Found the reference for those curious:

Powder Post Beetles

Phil Pellitteri, UW Insect Diagnostic Lab Revised: 4/27/2004 Item number: XHT1053 Powder post beetles attack porous hardwoods such as oak, walnut, mahogany, hickory and maple. Unheated buildings, very damp basements, barns, seasoned firewood, and lumber stored outdoors are most often...

hort.extension.wisc.edu

For small objects such as picture frames, freezing will control powder post beetles problems, if the object is taken from a warm, active state and placed at 10°F or colder for three days. Warming the object up for 48 hrs or more and then re-freezing improves control. The sudden shock of the temperature change more than the cold kills the beetles. For other wood items (e.g., newly installed trim), replacement may be the most cost effective management strategy.

 

[Ross Berning]

Another good reference!

Powderpost Beetles | Entomology

entomology.ca.uky.edu

It’s a long but insightful article. Some snippets

The three most destructive groups of powderpost beetles are the lyctids, anobiids, and bostrichids. Each group contains several species capable of damaging wood materials.

Lyctids seem concerning but aren’t going to destroy your house

Lower starch levels also make it harder for the larvae to complete their development. In newly seasoned wood with abundant nutrients, egg to adult development occurs in less than a year. Conversely, as wood ages, starch content declines and development slows to the point where some beetles may not emerge for two or more years if at all. Consequently, infestations eventually cease and die off even without intervention — an important factor when weighing treatment options (see ‘Managing Infestations’). Small numbers of beetles developing within wood may continue to emerge for up to about five years. This is due to diminished suitability of the wood rather than from new infestation.

These guys sound worse:

Bostricid powderpost beetles are more serious pests of hardwood than softwood. There is little risk to softwood framing within homes. Similar to lyctids, bostrichids usually attack newly processed woods with high starch and moisture content. Tropical hardwoods (including bamboo) are especially vulnerable to attack, which often occurs prior to importation. Although bostrichids seldom re-infest wood after the first generation emerges, extensive damage can occur the first year due to a high initial population and rapid development.

In humid areas these are a real concern:

Anobiid Unlike the powderpost beetles discussed previously, anobiids can seriously damage beams, joists, and other structural components of buildings. Anobiids prefer to infest moist wood. A 13-30% moisture content is required for development of the larvae. Consequently, infestations are most severe in damp crawl spaces, basements, garages, and unheated outbuildings (Figure 4). Buildings with central heating and cooling seldom have sufficient dampness to support beetle development in living areas or attics. Unlike lyctids and bostrichids, anobiid powderpost beetles can digest the cellulose within wood, and are less dependent on starch and other nutrients that decline over time. This allows them to attack and infest wood regardless of age.

Management:

Powderpost beetle infestations often die out of their own accord.

Powderpost beetles can also be killed by placing smaller items such as wood carvings and picture frames in a deep freeze (0°F) for 3-7 days, again depending on wood thickness.

Given they survive the winter this is surprising!

It references another article on sanitizing household items with PPB:

Thermal Deinfestation of Household Items | Entomology

entomology.ca.uky.edu

Insects are unable to tolerate sudden, unanticipated extremes of hot and cold. In fact, most insects, being cold-blooded, have rather narrow temperature ranges within which they can survive. Heating and chilling deinfestation methods have been used by museums, furriers, and the food processing industry for years.

It says a freezer or oven treatment will do the trick! A microwave is not encouraged because it’s too hard to manage the temperature.

Into the deep freeze it goes!