Douglas Fir Mast, CPES - use in restore/refinish?

[rmiller3]

I am presently stripping many coats of varnish from 40 year old Doug fir rectangular hollow mast. Varnish had broken down in many places and water certainly did track under the neighboring areas for some distance. All glue joints appear to be nice and tight.

Some such areas are stained black (on which I intend to try oxalic acid prior to serious sanding), others seem quite unharmed.

My concern is a few areas which ironically seem quite dry, where the grain has risen a bit (slightly fuzzy to the touch in spots), and I can get my knife in about 1/16" to 1/8" in places.

My question is whether it would be reasonable to coat the entire exterior of the mast with CPES, prior to multiple coats of varnish?

Obviously, I will not be able to coat interior surfaces. Further, many pieces of hardware and screws for sail-track, etc, will have to penetrate the surface, albeit with plenty of bedding compound (eg: Boat Caulk, or the like).

The goals of CPES application in this case would be to stop any rot, (if there is any active rot at this point), and increase strength if that is compromised to some dgree at areas described.

Any thoughts?

Thanks very much.

Robert

[Peter Malcolm Jardine]

Oh oh... Here we go with another CPES controversy. :D

But seriously...I have used CPES fairly often on a number of outside varnished surfaces... My rails, which are six inches wide and completely bright (36 foot boat) and I report good results. I also did my transom, which is bright, and I would have to say mediocre results. I use CPES to shoot into soft or suspect areas of wood in my superstructure, which are maybe a couple of small places a year.

Hey... CPES is one way to skin the cat, and it works reasonably well. I can recommend it and feel okay about the product. If your mast is nice and dry and bare, Warm Linseed and Turps works pretty damn well too. All my smaller pieces of brightwork I use linseed and turps. Hard to argue with history and natural products I say.

[JimConlin]

If memory serves, CPES was originally developed for treating superficial rot in punky architectural trim. If I have some punky pine in the base of a porch column, and this stuff firms it up so that it'll hold paint(Kirby's if you like), that's fine. Such trim work is expensive to replace. If it fails, the house won't come down. Worth a try.
I do recollect the gougeon's testing which revealed that solvented epoxy's strength was badly degraded, and I therefore would be very reluctant to assume that CPES had structural values approaching tat of the compromised material until I see lab test data proving otherwise.

[Jagermeister]

According to Smith & Co., their CPES is not simply thined epoxy. They specifically say that just adding solvents won't accomplish the same things because the solvents just evaporate before the CPES can soak in. I don't recollect exactly of what their formulation consists, but they say its different.

As I'm refinishing a 40' solid spruce mast, which the former owner only varnished as far as he could reach on ladder (fear of heights?), I am planning on at least a couple of coats of CPES prior to 2-part polyurethane. The upper two thirds look very much like the mast Robert describes - blackening, raised grain, roughness. As the stick isn't beefy to begin with, I'm leary of sanding it away.

The choice of CPES stems party from my desire to use the 2-part poly, so I won't have to do this again anytime soon. Although linseed oil & turpentine works great for things I can get to easily, it is my thought that using it on the mast would pretty much dictate a varnish overcoast, with attendent frequent refinishing. In this case it is my innate laziness that leads me towards CPES with 2-par poly overcoat.

At least its better than wrapping it in fiberglass, eh?

[Scott Rosen]

To answer your questions--yes it would be reasonable to apply CPES to your mast, after you have stripped all old coatings, and after you have removed any obvious rot. I don't think the areas you describe are compromised in strength to any meaningful degree. If there is a structural weakness, you should not look to CPES for a quick fix. It's great stuff, but it's not a substitute for a proper mast repair.

It would not be reasonable for you to think the CPES will miraculously stop all future rot. Hollow masts are a special case. If you're going to get rot, you are just as likely, maybe more so, to get it from the inside. The key to longevity is to keep water out of the inside of the mast, which is easier said than done. If the glue lines are sound, that's a good sign.

[paladin]

...and I think ONE coat is advised...multiple coats lead to a shiny finish and must be sanded prior to painting on other stuff....

[Bob Cleek]

What Scott said. You will not be able to bleach the black out of doug fir. It will even the color overall some, and should be used, but only after you have sanded out the black. Remember, everything on the spar will look darker when you put finish on it. Sand well (you aren't going to take more that 1/8" at very most) and bleach. Make sure it all dries well. Then soak it (one good coat until it stops drinking it) with CPES, paying particular attention to all the fastening holes. Lay on your finish (varnish or LPU) and then reinstall your hardware.

DO NOT use any bedding compound other than Dolphinite for the fittings. They will have to come off again some day. DO NOT use polysulfide bedding compounds!!!

DO NOT expect CPES to "cure" rot. It is only a SEALER (Clear Penetrating Epoxy SEALER). As such, it is an excellent foundation for later coatings. It will not make wood "waterproof" or "plastic" or anything else. Despite what the "Rot Doctor" says, it cannot be used to "plasticize" any STRUCTURAL rot. I wouldn't use it for that ever. (The "Rot Doctor" is some outfit that simply buys Smith's industrial CPES and puts it in a can with a boat on it and a much higher retail price!... along with making a lot of very questionable claims for the product.)

[rmiller3]

DO NOT use any bedding compound other than Dolphinite for the fittings. They will have to come off again some day. DO NOT use polysulfide bedding compounds!!! Thanks to all for the many replies and good advice.

I think I have used mostly polysulfide products over the years... on several wooden boats and spars. If this is not the best choice, I thank you for letting me know that... but I wonder if I might ask you to expand on this a bit?

What are the constituents of Dolphinite that make it the better way to go? And what are the weaknesses of polysulfides in this use of which I should be aware (I guess I personally haven't had these products fail as I've used them)?

Thanks for any info.

Robert

[Scott Rosen]

There's been a lot written on bedding compounds.

Polysulfide will do an excellent job of keeping water out. The downside is that it is a strong adhesive and may cause some damage when you try to remove the fittings for painting, inspection, etc. If you are bedding fittings to a varnished surface, then the PS will probably cause the varnish to rip off when you remove the fitting.

Dolfinite and other oil-based compounds are made to be easily removable. They are ideal for bedding fittings on painted and varnished surfaces. They are not 'permanent'; nor are they intended to be.

[rmiller3]

Addendum to above post:

I should say that my staement above assumes that Life-Caulk is a polysulfide...
I guess I'm not even certain of that.. and should look it up. It is Life-Caulk that I've used for... what seems like forever.

And it is that that I would like to address as to whether or not that is the best choice for bedding hardware. (polysulfide or not)

Thanks again.

[Matt Cohen]

Yes, Boatlife Life Calk is a polysulfide

[westinghouse]

Yeah it's the Life Seal that's a silicone polyurethane mix, but the Life Calk is polysulphide.

[rmiller3]

If I may, ... I'm still not certain WHY polysulfides should be avoided in bedding hardware.

Info?

Thanks.

Robert

[Nicholas Carey]

Originally posted by rmiller3:
If I may, ... I'm still not certain WHY polysulfides should be avoided in bedding hardware.See this thread:: Removing Sikaflex (http://www.woodenboat-ubb.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=012305)