wood preservative

[mpeverly]

Hello. I am finishing a small skiff made of eastern white pine with tung oil over raw wood all over inside and out, wondering if anyone knows a good wood preservative to mix in to prevent mold and fungus. Copper naphthenate has been suggested but seems pretty hard to find and I suspect would make the finish green. i considered using tar but have been told would alwyas be sticky. Not interested in anything epoxy or urethane related, definitely going to use oil...thanks

[Cuyahoga Chuck]

You're going two different directions. Anti-microbials are poisons. The water and the microbes get in but the microbes get deep-sixed.
Surface coatings, paint, varnish, urethanes and epoxies are barriers with varying abilities to keep moisture out. Tung oil doesn't fit in either catagory and will need a better barrier. The question then becomes what coating will bond over the tung oil.
I use epoxy and always apply it to a clean, uncoated surface. Epoxy is one of the best water barriers and it's protective ability and lifespan depend on being able to lock on to the surface it's applied to. Since epoxy needs UV protection I always apply varnish or urethane for that purpose and will choose a tinted product if I want to alter the shade of the finish.
Charlie

[Terry Etapa]

I've found that unless some "bug killer" is added, mold will grow on the linseed/turp mix. I've got steel nails as plank fasteners, and couldn't use the copper naphthenate (USCG NVIC 7-95) (http://www.uscg.mil/hq/g%2Dm/nvic/7%5F95/n7%2D95.htm) . I ended up adding about 10 - 15% by volume of a zinc naphthenate wood preservative to my mixture.

The zinc isn't as good as the copper, but it's clear and doesn't effect ferrous fasteners.

[mpeverly]

Thanks for your input Charlie. But I have made enough boats with epoxy and it doesnt suit me. I have heard of formulas for impregnating a boat with oil which call for 1 part oil, 1 part turp and 1 part "clear wood preservative" but cant get a very good idea exactly what this wood preservative is or what would be a good one to put in one of these old fashioned recipes. so if anyone knows about impregnating wood with linseed or tung oil and the best preservative to add, I would be curious...

[mpeverly]

Originally posted by Terry Etapa:
I've found that unless some "bug killer" is added, mold will grow on the linseed/turp mix. I've got steel nails as plank fasteners, and couldn't use the copper naphthenate (USCG NVIC 7-95) (http://www.uscg.mil/hq/g%2Dm/nvic/7%5F95/n7%2D95.htm) . I ended up adding about 10 - 15% by volume of a zinc naphthenate wood preservative to my mixture.

The zinc isn't as good as the copper, but it's clear and doesn't effect ferrous fasteners.

[Bruce Hooke]

Ummm...I certainly would not try to apply epoxy over tung oil! I don't think the epoxy is going to stick very well! Using an oil finish on boats without anything on top has a long history.

It seems like most of the mixes I've heard about have been based on linseed oil rather than tung oil. Among other things, tung oil is kind of pricy. I've used plenty of tung oil, but always on furniture. I just pulled down off the shelf my copy of Finishing by Walt Simmons (which is my bible when it comes to finishing boats), and one traditional oil finish he recommends is RAW linseed oil with a bit of Japan Drier (quarter pint drier to a gallon of Linseed Oil). He also goes into some more complicated mixes that include some varnish, as well as a tung oil based mix as well as lots of useful information about the prep-work for an oil finish.

As to your original question...I have never heard of anyone adding anti-microbials to an oil finish. The oil itself should do quite a bit to resist that sort of stuff, but maybe there is something out there that you could add for even more effectiveness. I know they put some sort of anti-microbial in exterior house paints...

[mpeverly]

oops, I messed up my reply. anyway, thanks terry. I think that's the stuff I am looking for. When you say 15% of the zinc naphthenate is that 15% of some product with the zinc in it or of "straight" zinc naphthenate? I have looked for this a little but have had trouble. Can you reccomend a product for this or a place to get zinc naphthenate? thanks!

[mpeverly]

thanks Bruce, I'll check out that book. I wanted to just use oil, but many people have told me mold would develop. I've also been told to use raw, boiled, tung instead of linseed. I guess I should just try something and see what happens...

[Bruce Hooke]

Don't use raw linseed oil without something added to get it to dry. Either varnish and Japan Drier will do the trick. Walt Simmons claims that of late the quality of the boiled linseed oil he's seen has been pretty poor, which is why he went back to creating his own mixes using the raw stuff.

I should note that this book is 20 years old so I'm not sure what might have changed in the interim. It looks like he has come out with an updated version: http://www.boatbuildingbooks.com/finish.html

The Jamestown Distributors website seems to be having problems, but I'm pretty sure I've seen in their catalog some of the preservatives that have been discussed.

[ 11-15-2005, 03:48 PM: Message edited by: Bruce Hooke ]

[Dan Lindberg]

FWIW, when I "oil" an old canoe, I add one of those little packets of mold/bug killer sold in "home stores" as paint additives to prevent mold. When well mixed, you can't tell it's there.
It usually comes in 1 oz packets sized for 1 gal paint.

Dan

[Terry Etapa]

I use an oil base zinc naphthenate wood preservative. It's about 3-4% zinc naphthenate. I believe I bought it at a Home Hardware store in Canada. When I looked for it in Seattle, all I could find was water base.

I'll try to find a jug, and see what brand I bought.

[mpeverly]

thanks Dan and Terry. The packet sounds extremely easy. I'd be curious to see what chemical they use, but if you say it works for oiling an old canoe, that's perfect. as far as zinc naphthenate I just found a company online, "jasco" that makes zinc naphthenate and copper naphthenate based wood preservatives, some water based and some oil based. They have one called "copper clear" which is oil-based, seems like it might be good and presumably clear.

[Bruce Hooke]

Jamestown Distrubutors sells Cuprinol Clear. I can't get the URL to work as a link so you will have to copy and paste it:
[http://www.jamestowndistributors.com/product;part;10240;process;search;ID;,Paints,Teak. Oils...Wood.Finish,Finishes, Cuprinol]

[ 11-15-2005, 06:09 PM: Message edited by: Bruce Hooke ]

[RosJoh]

I think the wood preservative that you should use is Behr Clear Wood Preservative, which is available at Home Depot or Lowe's [can't remember which]. It is copper presevative in a clear water repellent petroleum distillate solution. It should be put on bare wood, let dry before using tung oil sealer. I suggest using Waterlox tung oil sealer, reported to be the best. See www.waterlox.com (http://www.waterlox.com) for dealers in your area.

[Ken Hutchins]

Here is the latest info on green and clear preservatives. Cuprinol made both the clear and green for many years, Sherwin Williams bought Cuprinol and like so many other company mergers something has to go, well finally they decided to quit making the preservatives, I recently bought 4 of the last 5 gallons of green that Jamestown had after not being able to get it at SW, by now the last gallon is probably gone.
So what else has happened? Well recently Lowes opened a store up here in New Hampshire and what do I find sitting on the shelf Jasco GREEN AND ALSO BROWN preservative the green is 25% copper Napthanate which is 2% higher than Cuprinol was. So I went to the Jasco website and found that they also make CLEAR copper based. The WEB site lists the clear as available at Home Depot, Ace Hardware, Do It Best Hardware, and other places so I ordered 3 gals. of clear from the local Best store, Ace would only get it if I got a full case.
So screw Sherwin Williams, it is available from Jasco. I have used the Jasco clear and I like the results.

[Thorne]

Sounds like you folks have it pretty well figured out.

One possible resource might be our forum members in Scandanavia, as I understand finishing boats just using oil is a fine old tradition there that is still actively followed. I've read somewhere that the process takes many, many coats and involves some pretty exotic oils and natural additives -- possibly pine tar?

[mpeverly]

thanks to everyone for advice. I think I'm going to try the jasco copper clear. I will let you know how it goes...

[J P]

I wonder about using something like Tim-bor or Bora-care/Mold-care.
http://www.nisuscorp.com/timbor.html

[seo]

Most of the Cuprinol-style copper napathanate preservatives are mainly mineral spirts. Spirits is the vehicle, CN is the active ingredients. So if you're going to thin the oil, whether it's tung or linseed, raw or boiled, why not use Cuprinol to thin it out.
As far as Raw oil vs boiled, this comes from my sister-in-law's father, who worked as a chemical engineer for Interlux for many years. According to him, the object of "boiling" linseed oil is to make it harden. To make it really harden, they add japan driers to the oil as well as boiling it. That's why it's labelled as being toxic. Jap driers are not good to drink. Raw linseed oil/linseed cake can be used as a livestock feed supplement.
This does raise the question of whether it makes sense to buy raw linseed oil and add driers. If you want it to dry, buy "boiled." If not, buy raw. If you want it halfway in between, mix the two half and half. I have spent lots of time over the past twenty-some years mixing my own special paint mixtures. Haven't struck gold, but it's interesting, and doesn't seem to hurt anything.
I think the big advantage of Tung over linseed is that Tung doesn't turn black in sunlight.
seo