I make my own wood preservative. I could run out and purchase a similar preservative for about $95 a gallon or I can spend about $10 and make my own. I make a concentrate that I can store and when desired mix with equal parts of water use in a garden sprayer on my logs.
My ingredients for a home-brew wood preservative include Borax, Boric Acid and Propylene Glycol.
I can get Borax at the local supermarket in the laundry soap section - 20 Mule Team Borax. Its been available since 1891.
Boric acid as we have discussed in earlier posts is also easily obtained.
Propylene glycol is also easy to get. Propylene glycol is the base for earth-friendly antifreeze. I go to the local auto parts store and get a gallon of environmentally friendly antifreeze. If you are planning on making your own then CAUTION: READ THE LABELS! DO NOT under any circumstances use antifreeze with a base of, or containing any amount of ETHYLENE GLYCOL. This is nasty stuff folks DO NOT use. Ethylene glycol can be fatal and must be avoided for this application.
If you are thinking of making this preservative then take every precaution necessary. This post is not meant as a “go out and do it” only as an explanation of what I do. As in the handling on any type of preservative or insecticide YOU are the one ultimately responsible for your actions.
With that said - Now, how do I find propylene glycol based antifreeze? I read the label. I ask for RV and Marine antifreeze then read the label again to confirm that it is propylene glycol and NOT ethylene glycol. Propylene glycol based antifreeze is generally used as an additive to potable water systems in addition to being an engine coolant.
Making the wood preservative is rather simple. I’ll use above ingredients and a high-sided pot or kettle a candy thermometer, a scale, and a stove.
I pour one gallon of propylene glycol into the pot on the stove and heat. I make sure that all stove vents are on and that the room has good ventilation. I add 4 pounds of 20 Mule Team Borax and stir in and then add 3 1/2 pounds boric acid and stir in.
I keep stirring the mixture until completely dissolved and it takes a while.
I’ll need to heat the mixture to reduce the water content. I make sure to stir the bottom of the pot to prevent crystals from forming.
It takes some time to get to this temperature as what I’m doing is reducing the mixture by boiling off the water. While boiling I do not walk away as once a certain amount of the water boils off the temperature rises very very quickly. By the time the mixture has reached temperature I see that the mixture has become a very thick substance.
Once it has reached a mellow boil for a while I know that most of the water has been boiled off. I turn off the stove and let it cool.
Once cool I pour the mixture into a gallon container. This is my concentrate. Not all of the borax and boric acid will remain dissolved — there will be some degree of separation. I simply remix well when diluting for application.
This is similar to the stuff that sells for $95 a gallon - with a little time I just saved myself $85.00 and have a very effective preservative.
Before I apply the preservative to the wood I must 1) make sure that the wood is clean of dirt and debris and 2) dilute the concentrate. I dilute with a 1:1 ratio. For example; one gallon of concentrate to one gallon of water.
I make sure that when I dilute from the concentrate that I mix thoroughly until the solution is uniform. I use the diluted mixture within 24 hours of mixing. I do not apply the concentrate to the wood. I use common sense and protect myself and others by wearing goggles, a mask — a good one - not those cheap paper dust masks, a long sleeve shirt and I don’t spray into the wind. I also make sure to cover plants where intend to spray and keep kids and pets away. I use heightened precautions. — I read the label of each product you I’m using.
I use a garden sprayer with a flat nozzle which gives me better control when applying to the logs.
How and why does this work? Propylene glycol is very hygroscopic and as a result will penetrate deep into the wood or logs be they wet or dry. The propylene glycol acts as a carrier for the borax and boric acid drawing it deep into the wood. Although I will dampen the wood with water before spraying to help act as a catalyst I do not apply when it is raining or snowing. All three substances will kill off mildew and mold. As the log dries the boric acid and borax will form crystals within the wood. Both are great insecticides and also help to prevent mold and mildew.
I will soon post another recipe for a wood preservative that I use that does not use propylene glycol.
Feel free to leave a comment or a recipe that you have successfully used.
17 responses so far ↓
1 Bearfort Lodge // Jan 5, 2007 at 12:55 pm
Moving and Restoring a Hand Hewn Log Home
Paul, as addressed in the previous post, is tackling a major rebuilding and restoration of an outstanding hand hewn log home that he disassembled and moved from Pennsylvania to his property in West Virginia. Disassembling a log home is a long laborious…
2 Paul Proulx // Jul 30, 2007 at 4:56 pm
Hi,
I tried making your borate solution yesterday. I followed your directions almost to a T. I actually stopped before 260 deg. because it was becoming to hard. So I mixed in a bit more of the Propylene glycol and that seemed to have made it a bit more workable. I then poured it back into the gallon jug which with all ingredients did not fill it. Today it is a solid block. I used your recipe of 4lbs borax, 3.5 lbs boric acid per gal. of glycol. Any ideas of what went wrong, of did you use yours right off of the stove? I’m soaking the jug in hot water right now to hopefully turn it back into a liquid that can be mixed with water. Thanks, -Paul
3 Bearfort // Aug 3, 2007 at 5:32 pm
Hey Paul — Hmmm — Im not sure what may have happened - I have not had that situation. You will find that a great deal of the boric acid does not dissolve completely but I have never had it turn hard on me. I hope that you are doing this on a burin outside — and that if you made it in your kitchen that your kitchen does not have the lingering smell of a garage.
I do believe that if you stir in either glycol or a little water you should end up with a slurry that is more manageable.
This it out with either glycol or a little water. — Glycol has a reaction when on the stove that when heat is applied for a period of time the water will evaporate off - however there will come a point at which the glycol will begin to evaporate as well leaving you with a brick of material. It sound like somehow you passed that point.
The mixture is still usable with a little dilution. The point of the glycol is that it will follow water into the log and with it pull the crystals of boric acid. Both materials will help to kill rot/mold/fungus and bugs.
4 Paul Proulx // Aug 29, 2007 at 8:36 pm
I figured out what was wrong. I misread the weight on the 20 Mule Borax box. I thought it was exactly 4lbs and it was 4lbs, 12 oz., so I added to much borax on the first batch.
Also I found I went through this solution pretty fast, so on the next 7 gallons of glycol I made it just before I was going to use it. I found that if I brought the glycol (in one gal. batches) to a boil, added the borax, brought it back up to a boil and added the boric acid and brought it back up to a boil again, it would thoroughly dissolved everything. I then added water to make two gallons and used it a few hours later. This saved a lot of time and it also applied easier when warm, as a cool glycol solution tended to clog the nozzle on my sprayer (even with the correct mixture). I also found that it was much cheaper to just go ahead and buy 50lbs of boric acid then to buy a little at a time. Overall, I used 35 lbs. to do my cabin and have 25 lbs. left over :).
It applied pretty easy, but in a few spots, I may have sprayed on to wet as I now have to go over with an Osborn brush to take the white crystals off of the logs. The crystals come off easy and I have to do this anyway since I had the logs corn blasted and it leaves the logs kind of roughed up, although it doesn’t look like it. Thanks for the great money saving idea..
P.S. 8/29/07: I’m going to be chinking with a lime mortar of which the limestone is going to the kiln tonight to make my putty.
5 Bearfort // Aug 29, 2007 at 9:04 pm
Hey Paul it is unfortunate that you had such a tough time with the mixture.
Ive been making it and using it successfully for a long time.
Id be more than happy to talk to you about it — Ive sent you an email with my phone number.
Thanks! — Yes — I have received your email and number and will give you a shout.
How much lime putty do you normally make?
6 jerry // Sep 5, 2007 at 3:37 pm
COULD YOU E-MAIL THE MOST SIMPE SOUTION TO PRESERVE MY LOGS….ALSO DO I USE THE PRESERVATIVE ON THE LOGS PRIOR TO THE CHINKING…..WHAT WOULD YOU SUGGEST TO PLACE BETWEEN THE LOGS BEFORE ADDING THE CHINK…..APPROX.3-4 INCHES GAP….THANKS JBR
7 Randy // Oct 30, 2007 at 3:41 am
I loved your site!
I was wondering if you new how to stop aq log from rotting more. If it has started already
8 Randy // Oct 30, 2007 at 3:42 am
I loved your site!
I was wondering if you new how to stop aq log from rotting more. If it has started already
9 Bearfort // Nov 12, 2007 at 5:29 am
Hey Randy — Thank you — I appreciate that
The propylene glycol will kill off the mold, mildew and fundus and help to prevent the log from further rot — the bet thing however is to trace back to the root of the problem.
Water can travel in strange ways — and its always best to stop it at the source.
Is there a particular situation?
10 Monica // Apr 28, 2008 at 10:21 am
We have been peeling logs for our home for a week now. We want to put some sort of preservative on them. But we have found that boric acid is really expensive - only place we could find to get it was a drugstore. Is there somewhere else to buy it cheaper? We are also wondering why you can’t put propylene glycol mixture on the inside half of the log?
11 Bearfort // May 7, 2008 at 12:44 am
Hello Monica -
Here is the best place to get your boric acid
Give them a shout and speak with Mike. The boric acid comes in a bucket and is very very reasonable.
12 Bearfort Lodge » Home Made Wood Preservative For Log Homes // May 7, 2008 at 8:55 am
[...] found your post about the homemade wood treatment very informative! You mentioned at the end that you would post a recipe that didn’t use the [...]
13 Greg // Jun 20, 2008 at 8:13 am
Built our log home in 1979. Have a major insect, mold and fungi problem. Found your recipe for the RV antifreeze, Borax and Boric acid. Do I have to cook it or can it be used right after mixing it? Is it just the ends of the logs you spray or the whole house. Would appreciate your response.
Thanks
Greg
14 Bearfort // Jun 21, 2008 at 7:05 am
Hello Greg — Sorry to hear about you situation. NO - you do not have to cook it down - it CAN be used right after mixing. You can pray the material on the affected areas. Apply liberally on the ends of the logs as the capillary action of the wood will help to pull the propylene glycol mixture into the log. You can spray the entire exterior with the mixture - HOWEVER.
I would make a mixture with the propylene glycol and boric acid or Penetreat on the end of the logs. For the rest of the log I would use just a mixture of the Penetreat (boric acid) and water mixture.
The boric acid will dry out and kill off the mold as well as kill off insects.
The only time that I use the propylene glycol mixture is for rotted wood which I apply to the ends and the particular area of rot.
15 Patrick // Jun 28, 2008 at 12:17 pm
I made a solution of 1 cup Borax, 2 cups boiling water to dissolve. I added this to 1 qt plumbers antifreeze and approx. 2-3 qts cold water. My cabin is 11/16 tongue and groove boards and required 2 gallons for one “coat.” So far I haven’t noticed the ants “repopulating” but time will tell…
16 Monique // Aug 4, 2008 at 6:32 pm
Hi There, I am wondering if this solution is safe to use on the inside logs of our home. Also, did I read correctly that I do not have to cook the solution? Can I just mix the ingredients then apply right away? I am thrilled at finding this site, all other preservatives were so expensive.
Thanks for your help, Monique
17 Monique // Aug 4, 2008 at 6:33 pm
sorry, i made a mistake on my email address, I have corrected it now.
Leave a Comment