Making My Own Home-Brew Insect Eradication Solution

A topic that I covered during Groopstock 2014 and emerged again at Groopshop 2016 is dealing with active insect infestation in furniture or other wooden artifacts.  By request here is my protocol for dealing with such an issue.

If you determine that there is an active infestation – the presence of frass, a granular excrement and wood pulp mix in tiny pellet form (it often looks like very fine sugar except it is tan in color), or pupal exit holes the walls of which are the color of fresh cut wood – then there is little choice but to address the problem.

Generally the first option is often to find an exterminator who has a vacuum chamber large enough to place the infested artifact en toto (if part of it is infested, you have to assume everything is infested, and you should be suspicious of anything sharing the same uninterrupted space of the object in question) so that it can be impregnated with vaporous poisons like ethylene oxide or sulfurofluoride, or whatever is the toxin of choice these days.  I do not draw on this world any more and have lost track.

But there is another low tech, inexpensive, easy, and low-toxicity-to-humans method that works in a large range of applications: impregnation with liquid glycol solutions laced with borate complexes.  I have used this method for going on a decade and am very pleased with it.

The ingredients are simple.  The liquid required for this is RV/marine anti-freeze sold just about everywhere.  Heck, here in the hinterboonie village closest to me there are at least a half dozen places to get it.  The second ingredient is BoraSol WP, a disodium octaborate tetrahydrate powder I purchase from Quality Borate Company in Cleveland OH.  Ordering through their on-line store is a snap.  I bought a 22.5 pound case, which is enough to make over thirty gallons of insecticide.

The only tools you will need to mix and apply your home-brew insecticide are a 1.5-gallon plastic bucket, a paint stirring impeller from the hardware store, a drill to drive the impeller, an 8-ounce paper cup, and an inexpensive pump sprayer.  If the circumstances require them, you can add dropper pipettes or glue syringes to the kit.

The borate powder must be agitated in order to disperse it fully into the glycol anti-freeze liquid.  Heat helps, so I usually set the jug of anti-freeze in the sun for an hour or so to get it nice and warm, then pour the gallon of it into the plastic bucket.

Into each gallon I put two 8-ounce cups of the borate powder, which amounts to about 11 ounces of borate by weight, and fire up the drill and paint stirring impeller.  I agitate until the solution in the bucket is clarified.   It is now ready to use.  You can adjust the overall size of the batch but the ratio should stay the same.   For a gallon, I use two 8-ounce cups (5-1/2 ounces by weight per 8-oz. cup) of dry borate.  For a half Gallon, use a single 8-ounce sup.  For a Quart, use a single 4-ounce cup.

Note: the shelf life of the mixed borate insecticide solution is pretty short, I make a point to use it within 24 hours.

Using a brush if appropriate, or a sprayer, saturate the wood with the solution.  You are now done.  Really.  All you have to do is set it aside and wait for it to dry, which should be a day or two.  I have systematically sprayed all of the timbers in The Barn until they are dripping wet in order to eradicate any critters burrowing inside the wood (or fungi), and mitigate any future attacks.

Obviously for furniture you may not choose to literally douse the piece with the glycol/borate solution as it might affect any decorative or show surfaces, or lift veneer, etc.   Besides, when left on a coated surface the glycol solution gets pretty sticky as it dries.  If you have a piece of furniture you might consider applying the solution by brush to all the underside or backside surfaces (essentially everywhere that is not a presentation surface) and count on the fact that the glycol/borate solution wicks like crazy.  Depending on the species of wood the solution can travel 4-8 inches across the grain, and 4-8 feet (!) along the grain.  If swabbing, brushing or spraying does not fit your needs, you can even use droppers or syringes to inject it into the exit holes, as long as you do it adequately to provide the necessary concentration of the solution into the wood matrix.  You can remove any excess solution by simply wiping the surface with paper towels or cotton pads, followed by a pad dampened with distilled water, followed by a dry pad.

***Make sure to test this on an obscure surface of your object to make sure it does not harm the appearance!***

Note:  Any materials treated with borates are no longer glue-able with PVA adhesives as borate, including borax itself, is a gelling agent for PVA.  Adding borax to diluted PVA is how kids make “slime” in science class.  To my knowledge and by my experience and observation the borates do not interfere with any adhesive processes employing epoxy or hide glue.

The “official” option for following the same application procedure is to employ a fine product known as BoraCare, which is purchased as a concentrate and diluted 1:1 with warm water and used in precisely the same manner as I described above.  I have used BoraCare in the past with great success, but at about $100/gallon for the concentrate (or $50/gallon for the application solution) I switched to home-brew once I needed many, many gallons of insecticide for the barn.  The comparative cost is home-brew is about $8-10/gallon for application solution.

I will soon try to recount my process for the anoxic insect eradication technique we used in the museum field and is also applicable for many shop situations.