CHEMOTHERAPY FOR ROT (wood) and EPOXY KNOWHOW

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Model T Ford Forum: Forum (old): CHEMOTHERAPY FOR ROT (wood) and EPOXY KNOWHOW
Top of pagePrevious messageNext messageBottom of page Link to this message  By James O Behrens (Bigjunglejim) on Sunday, November 24, 2002 - 05:54 pm:

With all the wood used in Model T's, I thought the following information would be of interest to many.... Jungle Jim

Dave Carnell's Boatbuilding Page CHEMOTHERAPY FOR ROT

CHEMOTHERAPY FOR ROT
Once rot gets a toehold in wood it is difficult to cure completely -- it is like a cancer. Digging out the rotted wood
will still leave spores and water in the sound wood. After you fill in the
cavity with something like epoxy, the rot continues to flourish underneath.
Products promoted to make rotted wood sound and stop rot penetrate only until
they meet water, with which they do not mix. Under the solid repair rotting goes
on. With one exception (more later), the commercial products sold to treat dry
wood to prevent rot are completely ineffective against established rot in wet
wood because they are dissolved in petroleum solvents and oil and water do
not mix. There are two commonly available inexpensive materials that will kill rot in wood and prevent its recurrence. First, there are
borates (borax-boric acid mixtures) which have an established record in
preventing rot in new wood and in killing rot organisms and wood-destroying insects in
infested wood. Second, there is ethylene glycol, most readily available as auto
antifreeze-coolant. Glycol is toxic to the whole spectrum of organisms
from staphylococcus bacteria to mammals. All of the published material on
its effectiveness against wood-destroying fungi and insects that I am aware
of is the result of my investigations over the past 15 years.Both borate solutions and glycol penetrate dry and wet wood well because they are water-soluble; in fact, penetration by
glycol is especially helped by its extreme hygroscopicity -- its strong
attraction for water. For both, the fact that they are water-soluble means they are
not permanent solutions to rot in wood that is continually exposed to
water-below the waterline and in ground-where they will eventually be
extracted-dissolved out.I first was interested in glycol as a wood-stabilizing agent, where it is in many ways superior to polyethylene glycol (PEG),
and it was during this work that I realized the useful effect of glycol on
organisms, though I was pretty dense in interpreting the first experiment.The ladies immerse the stems of greenery such as magnolia branches in glycerin to keep them green. Glycol is very similar to
glycerin in all its physical properties and much cheaper, so I stuck a magnolia
branch in antifreeze. The next day it was brown. After the third attempt I
tumbled to the fact that the glycol was killing the greenery. This was the reason that
glycol never replaced glycerin in applications such as a humectant for tobacco
and an ingredient of cosmetics and pharmaceutical ointments, though it had all
the desirable physical properties.I had two 2" thick slabs of a 14" diameter hickory tree that had just been cut. I treated one with antifreeze and left one
untreated. I was looking at wood stabilization, not rot prevention. After about six
months stored inside my shop the untreated control was not only cracked apart,
but it was sporting a great fungal growth, while the treated slab was clean.The local history museum wanted to exhibit two "turpentine trees", longleaf pines that had many years ago been gashed to harvest
the sap that made everything from turpentine to pine tar. The trees delivered
to us after cutting were infested with various beetles and had some fungal
growth. I treated them with antifreeze outside under a plastic tarpaulin every
few days for three weeks. They were then free of insects and fungus and have
remained so after being moved inside and installed in an exhibit over four years ago.I took three pieces from a rotting dock float that were covered with a heavy growth of fungus, lichens, etc. I treated one with
antifreeze painted on with a brush, the second with a water solution
containing 23% borates (as B2O3), and left the third untreated as a control. They
were left exposed outdoors and were rained on the first night. By the next
morning the growth on the antifreeze-treated piece was definitely browning and the
borate-treated piece showed slight browning. After two months exposure
to the weather the growth was dead on the antifreeze- and borate-treated
pieces and flourishing on the control.I have a simple flat-bottomed skiff built of plywood and white pine, which has little resistance to rot. After ten years some
rot developed in one of the frames. It may have begun in the exposed end
grain. It consumed the side frame, part of the bottom frame, and part of a seat
brace fastened to the side frame. The plywood gusset joining the side frame
to the bottom frame was not attacked. I excised the rotted wood, saturated all
with ethylene glycol antifreeze to kill all the rot organisms, and there has
been no further deterioration in four more years afloat with wet bilges. I have
not replaced any pieces, as I am building another boat that can replace it;
that is more fun, anyway.I have a 60+-year old case of the fungus infection known as "athlete's foot". Many years ago it infected the toenails
extensively. The whole thing was pretty grotesque. My dermatologist and druggist both
assured me there is no known cure. About six years ago I started using antifreeze
applied under the nails with a medicine dropper about every five days. The
professionals are technically right. I have not completely cured it, but the nails
have grown out pink and thinned almost to the ends and I never have any trouble
with blistering, peeling, or itching between the toes as I had had for six
decades. No drug company is going to have any interest in this because the
information has been in the public domain for so long that there is no opportunity
for any proprietary advantage. The various wood-rotting organisms cannot be
anywhere near as tough.There are two types of borate products commercially available for treating wood-solid sodium octaborate for making
solutions in water (Tim-Bor® and Ship-Bor®) and a 40% solution of sodium octaborate
in ethylene glycol (Boracare®). Their equivalents and more concentrated
solutions can be easily prepared from borax, boric acid, and antifreeze at much
lower cost. Keith Lawrence, editor of Boatbuilder offered to sell me advertising if I wanted to go in the business, but I might run afoul of
patents (preparation for individual use is not prohibited), I would have to get
EPA registration, and I could not deliver products anywhere near as cheaply
as they can be made from raw materials available at your supermarket,
drugstore, and discount store.Glycol by itself has one big advantage over solutions of borates in either water or glycol. Glycol penetrates rapidly through
all paint, varnish, and oil finishes (except epoxy and polyurethanes) without
lifting or damaging those finishes in any way. You can treat all of the wood of
your boat without removing any finish. The dyes in glycol antifreeze are so weak
that they do not discolor even white woods. Once bare wood has been treated with
glycol or the borate solutions and become dry to the touch it can be finished or
glued. If a borate solution leaves white residues on the surface, it will have to
be washed off with water and the surface allowed to dry.This is my preferred process to treat rot. Once you find soft wood or other evidence of rot, soak it with antifreeze even if you
cannot do anything else at the moment. Paint it on or spray it on with a
coarse spray. Avoid fine mistlike spraying because it increases the likelihood that
you will breathe in unhealthy amounts of glycol. Put it on surfaces well away
from the really damaged wood, too. Use glycol lavishly on the suspect wood,
which will readily absorb 10-20% of its weight of antifreeze.Next dig out wood that is rotted enough to be weak. Add more glycol to wet the exposed wood thoroughly. Then add the 25% borate
solution of the recipe below so long as it will soak in in no more than 2-3
hours. Then fill in the void with epoxy putty and/or a piece of sound treated wood
as required. The reasons I use borates at all are: 1) it is a
belt-and-suspenders approach to a virulent attack, and 2) over a long period glycol will
evaporate from the wood; especially, in areas exposed directly to the sun and the
high temperatures that result.If there is any question about water extracting the glycol or the borates, you can retreat periodically with glycol on any
surface, painted or bare, and with borate solutions on bare wood.Glycol's toxicity to humans is low enough that it has to be deliberately ingested (about a half cup for a 150 lb. human); many
millions of gallons are used annually with few precautions and without incident.
It should not be left where children or pets can get at it, as smaller
doses would harm them, and they may be attracted by its reported sweet taste that I
have confirmed by accident. The lethal dose of borates is smaller than of
glycol, but the bitter taste makes accidental consumption less likely.

BORATE WOOD PRESERVATIVES:COMMERCIAL AND HOME-BREWED
Tim-Bor®: Solid sodium octaborate; dissolves in water to make approx. a 10% solution containing 6.6% borate (B2O3); about $3/lb. plus shipping. Ship-Bor®: Same as Tim-Bor®; $19.95/lb. plus $2 shipping.Bora-Care®: 40% solution of sodium octaborate in ethylene glycol; 27% borate content; $70/gal. plus shipping.Home-Brew Water Solution of Borates: Based on U.S. Navy spec. of 60% borax-40% boric acid (this ratio gives the maximum solubility of borates in water); 65%
water, 20 %borax, 15% boric acid; 15.8% borates; borax costs 54 cents/lb. (supermarket), boric acid costs about $4/lb. in drug stores (sometimes
boric acid roach poison, 99% boric acid, is cheaper in discount stores);
equiv. to Tim-Bor® or Ship-Bor® at 30 cents/lb. To make this solution mix the
required quantities and heat until dissolved. The boric acid, in particular,
dissolves slowly. This solution is stable (no crystals) overnight in a
refrigerator (40°F.), so can be used at temperatures at least as low as 40°F.Home-Brew Glycol Solution of Borates: This is equivalent to Bora-Care® diluted with an equal volume of glycol to make it fluid enough to use handily; 50% glycol
antifreeze, 28% borax, 22% boric acid. To make a stable solution you mix the
ingredients and heat till boiling gently. Boil off water until a candy thermometer
shows 260°F. This removes most of the water of crystallization in the borax. This
solution is stable at 40°F and has a borate content of 26%. With antifreeze at
$6/gal. and borax and boric acid prices as above, this is equivalent to Bora-Care®
at about $15/gal.

Dave Carnell's Boatbuilding Page EPOXY KNOWHOW

INVISIBLE BUTT JOINTS
In 1978 I first used a plywood butt joint of fiberglass cloth and epoxy resin to avoid having to make a scarph joint (not easy
and loses length)or use butt blocks (hard to work around). The joint is so thin
that careful feathering of the edges makes it invisible.In 1986 I wrote about the joint in Small Boat Journal. About the same time "Dynamite" Payson wrote in Boatbuilder about a similar joint concept. Years later I discovered that Joe Dobler
had used the principle well before our publication, as had Jack Chippendale in England.A piece of plywood bent around the side of a boat is carrying most of the load in its outer and inner plies. The load
(stress) on the convex side (usually the outer) is a tension load trying to pull the
wood apart. On the concave side (usually the inner), the load is compressive-the
wood is being pushed together. The invisible butt joint makes two pieces of
plywood one by building a skin of fiberglass and epoxy on each side. When you flex
the joint, the load is carried entirely by those two skins you have built.
I made joints in various thicknesses of plywood and tested them by breaking them in flexure with the maximum stress applied at the
joint. Joints that passed were ones where the plywood, not the
fiberglass-epoxy resin joint broke. My design basis for invisible joints in plywood is: for
1/4" plywood, 1 layer of 6 oz. fiberglass cloth on each side; for 3/8", two
layers on the top (outside of bend) and one layer on the bottom; for 1/2", three
layers on top and two on the bottom; for 3/4", four layers on top and two on the
bottom. Make the first fiberglass strip on top 2" wide and each succeeding one
an inch wider. On the bottom side make the first strip 2" wide and the second
one (if used) as wide as the widest strip on the top side. After you lay up the
joint cover it with a piece of 4 mil polyethylene film and squeegee or roll
it out. This presses the cloth layers together and feathers out the excess
epoxy onto the plywood. Peel the film off after the joint! ! cures and the surface
is smooth and faired so that very little filling or sanding is required.
If you use woven tape instead of pieces cut from cloth, the selvage may make a
ridge at each side of the joint. A joint with a single layer of 6 oz. cloth on
each side is about 0.020 in. thicker than the plywood at its thickest point and
tapers off to zero at each side. Two layers on each side adds about 0.030 in. at
the thickest point. The joint in 3/4" plywood with four layers outside and
two inside is only about 0.045 in. thicker at its thickest point. These joints are designed to use a minimum of material to get the ultimate strength. I would only make them with epoxy resin (not
polyester resin) because: 1) epoxy bonds the glass cloth to the plywood
in a stronger joint that will not peel apart; 2) epoxy will always
eventually complete its cure; 3) there is no fire hazard with epoxy; and 4) there
is less of a toxic hazard with epoxy.Originally, both Payson and I made the joint on one side and turned the piece over to complete the joint. The turning over is
fraught with danger of destroying the joint that is very weak at that point.I have gone to laying polyethylene film on a smooth surface, laying the wetted out fiberglass tape (I use cloth to avoid
the selvage) on that, epoxy coating the face of the plywood that goes
against that, laying the plywood on the wet tape, filling any least void between the
plywood edges with thickened epoxy (this is critical, as any voids between the
butting plywood edges can make the joint weak), epoxy coating the upper plywood
joint surface, laying on fiberglass and wetting it out, covering with poly
film, laying on a smooth board, and weighting the assembly with concrete
blocks. In fact, the last time I did it I laid up a sandwich of two 16' by 20"
pieces for the side planks of a sailing skiff and cured them all in one operation.If you are making joints in plywood thicker than -1/4", make the bottom side of the layup the one with the fewer number of
fiberglass strips.

EPOXY IN A NUTSHELL
This is a distillation of my experience in using epoxy for 30 years and improving my techniques. I started using epoxy for
boatbuilding in the 1960s. This was before Gougeon came out with their West® system. I
was using generic epoxy from Defender and an amine hardener that was mixed 1:10
with the resin. Later I switched to Epon® resin and Versamid® hardener from a
surplus outfit in CA. This was a 2:1 mix and far easier to use.Then, as now, all resins and hardeners were made by a few major chemical companies. The companies selling products at retail
develop their formulations from commercial products.Resin and hardener are ingredients that have to be mixed in the correct proportion to cure to a solid with the desired strength
and hardness. If you want the mix to cure faster or slower, you pick a
different hardener. You don't change the mix ratio.Epoxy is far superior to polyester resin because it sticks to just about all materials, while polyester is not even a reliable
adhesive for laminating glass cloth to wood.If you mix your epoxy in the correct ratio it will eventually cure. If the catalyst you add to polyester does not kick it
off, it will never cure.Epoxy resin and hardeners have shelf lives of many years. I am still using a two-part surplus military epoxy putty that was
manufactured almost 25 years ago. The only exception to unlimited shelf life I have
found with epoxy resins is that the hardener for 1:1 mix systems thickens and
cannot be used after about a year.

GLUING LAMINATING
The most important use of epoxy resin is as glue, including gluing fiberglass to wood. Its advantage over most other
glues is that it will fill gaps; in fact, there always has to be some gap. If you
clamp too tightly the epoxy will be squeezed out so that the joint will be weak.
Adding filler to epoxy used as glue makes stronger joints, perhaps because the
filler keeps too much resin from squeezing out of the joint. One-inch boards
edge glued will break apart in the joint when it is flexed; add about 20%
pulverized limestone and the glued joint breaks in the wood. I add about 10%
limestone to resin when laminating fiberglass onto wood, also.

FILLERS
Fillers are added to epoxy resin to make putties for two kinds of uses that have greatly different requirements. Those used for
structural joints alone or in combination with fiberglass should be as
strong as possible. Putties used for filling and fairing must sand easily.The best filler for structural uses is pulverized limestone (flour fine, not gritty as ground limestone is). It mixes to
a putty that doubles the resin volume and is dense and strong. It is
universally available as a fertilizer material at under a nickel a pound. It is
difficult to sand. Portland cement is pretty much equivalent. Talc, another mineral,
is almost as strong and sands easily. It also is thixotropic (the putty
does not flow, but will spread). It is available from fiberglass supply houses
at around a dollar a pound. For filling and fairing applications hollow bead type
fillers sand most easily because they are hollow and break. There are three
kinds of beads: thermoplastic (Microlight®) which can soften with heat;
phenolic, which are usually dark-colored; and glass (Scotchlite®), which are white. The
glass beads make the lowest density filler and are the lowest cost. White
wheat flour from the kitchen is a pretty good filler for finishing putt! ! ies.

STRUCTURAL JOINTS
A fiberglass-epoxy butt joint of plywood can be as strong as the plywood itself. See "Invisible Butt Joints" above. Right-angle
joints in -1/4" plywood for rowing seat boxes, etc. can be made with just a 1/4"
radius bead of epoxy putty on the inside of the joint. I tack such a box
together with brass brads and then make the epoxy fillet joints. For angle joints
such as chines in -1/4" plywood a 1-1/2" fiberglass strip laid over a -1/4"
radius epoxy fillet on the inside and a 1-1/2" strip on the rounded outside edge
gives a joint that breaks by pulling the plywood apart. Bulkheads secured by a
1-1/2" glass strip over a -1/4" radius epoxy fillet on each side fail in the
plywood. All joints must have the weave of the glass cloth filled smooth for
maximum strength. Many designs specify much more glass than needed. Make up
short specimens of your joints, cure them, and test them-in a vise, by
standing or jumping on them, or by running your truck over them. If ! ! the joint
holds and the material breaks, your joint is strong enough.

SAFETY
The principal hazard of working with epoxy resins is from skin contact. The hardeners are the offenders. As a general rule, the
lower the mix ratio, the less the hazard (2:1 is less apt to irritate than 4:1),
but you should avoid all skin contact and wash thoroughly after any contact.
Wash thoroughly before eating, drinking, or going to the bathroom. Gloves
and clothing help protect you, if they are clean.

ENCAPSULATION
You will note that I have not mentioned epoxy encapsulation; i.e., coating both sides of everything with several
coats of epoxy resin. It has no advantages and is a waste of money and time that
adds useless weight. It won't turn lauan underlayment into marine plywood,
though it will make it cost nearly as much. It does not keep the water out of the
wood boat that lives in the water and a dry sailed boat doesn't need it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Gent, T-Town, OK (Billgent) on Monday, November 25, 2002 - 08:00 am:

Hi, Jim,

This is Reallly Amazing!
I'm going to get a copy to my podiatrist, who has been treating a toenail fungus I've had since the '50's.

The info on woodworking and rot treatment will also be Most Useful for numerous jobs I can think of; for example, two of the heavy oak doors of our church, which is about 75 years old, has had a problem with rot for some time.
We've tried to cope with this problem in a number of ways, none of which worked.

Your information will be most useful to us, because we're short of funds these days, and would cost about $4K to replace the doors.

Thanks__ Much__!!

Bill Gent


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Braymen (Sbraymen) on Monday, November 25, 2002 - 08:13 am:

Fantastic write-up. Thank you.
Steve


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joseph A. Stearns (Jstearns) on Monday, November 25, 2002 - 11:04 pm:

This was a great write-up. Thanks much for all the good information. I will be restoring my 1962 Century wood boat in the spring and it needs some bottom work. Your info will come in handy I'm sure.
Well, I must go now and give my yellow toe nails a little treatment. Thanks again. JOE


Top of pagePrevious messageNext messageBottom of page Link to this message  By Nicholas L Unger (Nick) on Friday, November 29, 2002 - 10:05 am:

Great write up. Will try on outside door frame of side door that is always wet. This is why I check this site every day. Learn so much about T and meet such good people. If you see a beat up 1923 Hack, say a big HI, Nick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Gent, T-Town, OK (Billgent) on Tuesday, December 03, 2002 - 09:14 pm:

The latest on Rot Prevdention; it's EEzy!
Sent a note to Dave Carnell, and here's the reply.
Most Interesting!! BG

Bill,

The percentages are by weight. My article included a recipe for making
an antifreeze solution that includes boiling away the water of
crystallization in the borax. I don't know your applications, but in
the five years since I wrote the article I have found that just
antifreeze is usually more efetive because it penetrates farthest
fastest.

Dave


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