iDRY Vacuum Kilns

Sponsors:

Home-made Bora Care

Started by clintnelms, October 03, 2016, 12:32:55 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

clintnelms

Anyone tried making home-made Bora Care? I ran across another forum in my searches about the product that has the recipe and directions for making it. I got some items I want to build for the house in the future, but I'm concerned about bugs coming out later. I don't have a kiln anywhere near me. Closest one I've found is almost 2 hours away. I thought about building a solar kiln, but from what I've read it won't sterilize the wood. So it seems Bora Care may be my best bet. But that stuff is way too expensive.

longtime lurker

We still run a borax dip and also pressure treat with borates for the cabinet species and a couple specialty applications.

The correct mix ratio for maximum borate loading in water is 60% borax (sodium octoborate) to 40% boric acid - both of these are readily available from agricultural supply places in 40lb bags. For the sake of convenience the mix we run tends to be 66/33... because its 2 bags of borax and one of boric acid and its close enough. Just keep adding the powders and stirring until it wont dissolve anymore.

Now heres the big thing. Spraying timber with borax isnt treating it with borax. Spraying will leave a residue of borate on the surface which is fine for a protective coat to keep pests out during drying etc. But its ON the timber, not IN the timber. Big difference. Getting borates into the timber to give long term protection is a whole different process to just spraying it.

Heres some options and pluses and minuses of them.
You can pressure treat with borate solution in a similar fashion to any other pressure treatment process (eg CCA). Its quick, cost effective, and treats the timber to a depth of a couple of mm (3mm = 1/8") of heartwood and total penetration of any sapwood. It doesnt treat in any deeper then that and if you dress the timber following treatment then theres a fair chance that you will remove the protective envelope of treated timber. This applies to all "regular" pressure treatment schedules and chemicals BTW, which is why CCA treated wood isnt green inside when you cut it in half. So the downsides there apart from needing a pressure treatment plant are thats its a shallow depth treatment.  Cut it, dress it, run a screw in it and you break the protentive treatment envelope in some way.
(Obviously you arent going to be putting in a pressure treatment plant for home use but you might be able to hire space in one at a mill that has one. if so you need to talk with them as they will have a required stack dimension to fit inside the treatment vessel.)

Next option is to block stack, formally referred to as the "Dip diffusion method".
Block stacking utilises a concentrated borate solution. You need some heavy plastic sheet laid out (concrete underlay sheet works well) , and a trough to place your timber in. Dip each board in the concentrated borate solution to get total surface wetness (ie it goes under the water) Then stack each board onto the plastic in a solid block and  cover with the plastic like wrapping a present and tape it shut. Tip any leftover solution over it before sealing it shut, the wetter it is in there the better! Leave it shut for several weeks, during which time the timber will uptake the borates.
Yah, it sounds counter intuitive, but from the little bit of experience I had with this process the strength of the borax solution is enough to ward off any serious fungal attack, and the other issue is that so long as the moisture level in there remains at a level similar to a living tree the fungal spores cant grow for the same reason they dont grow in living trees - too wet. As I said, wetter the better!
. It helps if the logs are dead fresh when sawn and treated so as to reduce the exposure of the wood to fungii before it hits the pack. About 3 weeks for 4/4, 12 for 8/4. This method is a cheap way of getting a treatment envelope as good as (and mostly deeper then) pressure treatment. The major issue with it as a process is that it works best with fresh logs and that obviously its too slow from a commercial standpoint. But it does work, and work well - this is old school small scale borate treatment.

Another method is to "cold soak" the timber in a tank with borate solution. Usuallly got to weight the timber down to stop it floating. We're talking 2 weeks of soak for 4/4 and 4 weeks for 8/4 so again its too slow for commercial production. the big plus of this is the depth of treatment is a lot deeper and the % retention of borates in the wood a lot higher. I'll cover what that means in a bit.

The method of treatment we use is the "hot and cold bath method" which is what we use here for a few specialty applications. Basicly we put the lumber into the same tank as a cold tank then heat it to 85C/185 F for 4 hours then let it cool to 60 C/ 140F and hold it there there for 16 hours for 4/4 or 20 hours for 8/4. Then we pull it out, and strip it out, but it cant go into a kiln for at least 5 days as the borax is still diffusing inside the timber. So we can run a charge through the trough in 24 hours which makes it fast enough for a small production mill if the tank is big enough.

The advantage to the two soak methods is that they treat the timber far deeper, and the borate loadings are higher. Borates tend to leach out so the more the merrier right? However the main advantage of the soak methods is that a sufficient loading of borate in the timber enables it to meet fire retardant ratings. Its an oddball specialty market thats quite lucrative if you can crack it, but thats why we still run a borate dip: its possible to load enough borate into timber with pressure treatment with repeated treatments but more cost effective to use a dip.

If you just want a reasonably friendly, exterior wood preservative treatment try Copper Napthenate, manufactured by Nisus corp. Its available as a concentrate at a reasonable price, requires kerosene/turpentine/diesel to thin it, and you can either paint it on or soak it on. Its reasonably environmentally friendly, but think fenceposts, utility poles, subfloor components that you aint going to touch because its CCA green and it takes a while for the smell of the thinner to go away. But its a reasonably effective long term treatment if you dont want the bugs eating your house anytime soon.
The quickest way to make a million dollars with a sawmill is to start with two million.

bandmiller2

Thanks Lurker that's the type of straight scoop we need. Frank C.
A man armed with common sense is packing a big piece

longtime lurker

Quote from: bandmiller2 on October 04, 2016, 07:01:48 AM
Thanks Lurker that's the type of straight scoop we need. Frank C.

You're welcome Frank. In Australia we're all treatment mad - got some of the worlds most naturally durable timber species and we still turn then CCA green or ACQ brown as a matter of principal so its a topic I know a bit about.

I learn bits and pieces or new ways of looking at things from you guys all the time - always a pleasure to give a bit back. John G
The quickest way to make a million dollars with a sawmill is to start with two million.

clintnelms

Thanks for the great description. I definitely learned a lot. However I'm asking about Bora Care for sterilization not really treatment for outdoor use. I have several projects in my head where I want to use some of my lumber I've milled to use in my house, for things like a table, headboard, and whatever else the wife wants. My concern are bugs coming out of the wood later on like powder post beetles and such. I don't have the ability to kiln and sterilize the wood. So bora care is my option. But it's expensive as hell. So I found the Home-made version recipe and was wondering if anyone has made it and had luck with it?

Ianab

If your furniture is going to be finished, like a table or headboard, then the varnish will prevent bug infections. You usually find bugs in the secondary unfinished wood, like furniture back panels or drawer sides etc.

This means you can spray your rough sawn wood with LL's borate mix as a surface protection while it's drying and in storage. Bugs that live in green wood die off as the wood dries out, so all you need to do is protect the wood from a new infection of PBB or similar that might infest the drier wood.

Then when you plane that off to build your table / headboard etc you are going to apply some varnish that will protect it from then on.

The pressure / soak Borate treatments would be more for unfinished wood, where it's going to stay dry, but could be exposed to bugs. Usually construction uses. Exposed to weather / water AND bugs then you need to more toxic commercial treatments
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

clintnelms

Well maybe I'm not understanding correctly what I've read on other post. I thought a lot of the bugs like PBB is already in the live tree. I've read where some have built things and then months later start seeing the little pencil holes from the beetles coming out. Seems I read somewhere that they started eating on other wood in the house. I don't want that. I know some spray their lumber with timbor soon as it comes off the mill, but that's only a preventative. It doesn't kill what's already in it.

longtime lurker

Any timber treatment combines 2 basic parts: the active ingredients that actually do the work of preventing decay, and the carrier solution used to get those ingredients into the wood. Plus other stuff like water repellents etc.

You also need to factor in application method which determines if the active ingredients are on the wood or in the wood. The 60:40 sodium octoborate/ boric acid mix is the same as Timbor or other proprietary borate wood treatments. If you spray it on wood it's on wood, I'd you diffuse it into the wood as outlined above its in the wood. If it's on the wood it can wash off, or gets removed during machining of the wood once dry. The biggest problem with spray treatment is that people don't use enough, so any holes or cracks don't get properly treated. Even if it's just a dunk in solution, total immersion of a board is always better, like these guys doing it hi tech tailing out here at the 2:55 mark.
https://m.youtube.com/watch?v=aBDMN-xVta0

The carrier solution is water, and this works best with green wood.

BoraCare uses the same borate ingredients mixed into a solution of glycol. Glycol is quite hydroscopic so it rapidly soaks into dry wood, taking the borates with it and depositing them in the surface layer. It's in the wood, but not deeply in the wood so again can machine off. It's a protective envelope of treated timber around an untreated core.

Probably the best lo tech way for small volumes would be to apply the Timbor type solution either as spray or dunk to the green wood. Dry it. Dress or machine it. Then apply the glycol based boracare type solution to the finished article before top coating with varnish etc. Applying boracare to green wood is pointless because you'll dress it off once dry, so could have had the same level of protection with the water based solution for a lot lower price.

Most of the commercial glycol or LOSP  based H2 clear ( i.e. no colour change like copper green) preservative systems also have a dedicated insecticide- usually permethrin - in the recipe as well. They are applied by pressure treatment post machining. Boracare is just a brush friendly version of those. You could probably add  Pounce500 to your home brew mix if you really want them dead forever, but it'd be a handle with gloves while wet type mix. Pounce500 is a dedicated lumber insecticide.
The quickest way to make a million dollars with a sawmill is to start with two million.

Thank You Sponsors!