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PostPosted: January 27th, 2013, 8:47 am 
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Location: Freeland, Maryland USA
In June 2008 I set up an experiment using various oil, varnish, urethane and epoxy as wood finish products.

The test: I coated sections of finish sanded ash gunwale with a variety of varnishes, urethanes, epoxies and oil treatments. All the varnishes were thinned (or not) as recommended.

The labeled sections of gunwale are screwed (left over stainless screws) into a piece of vinyl siding. All the screw holes were countersunk and varnish/epoxy/oil finished inside using a pipe cleaner. The test panel was screwed vertically onto my canoe rack out in the weather in partial shade.

http://i1285.photobucket.com/albums/a59 ... 250600.jpg

The finish coats
Top row:
Helmsman Spar Urethane (3 coats)
Sikkens Cetol Marine (3 coats)
Sikkens Cetol Marine Lite (3 coats)
Epifanes Clear Spar (3 coats)
Epifanes Rapidclear (3 coats)
Coronado Marine Spar (3 coats)

Bottom row:
Control (no finish)
West System Epoxy (105/206, two coats)
West System (two coats) with one coat of Coronado varnish overtop
GunwaleGuard (3 coats)
Oil mix (1/3 varnish, 1/3 boiled linseed, 1/3 turpentine) x 3 coats
Watco exterior oil (3 coats)


+++

4 ½ year results (June 2008 – January 2013)

I’m ready to take this ugly test board off of my canoe rack. I don’t think the results are going to change much at this point and I am curious to more closely inspect the various treated wood pieces.

Note: I did no maintenance to any of the pieces except for reoiling the GunwaleGuard, Watco and DIY oil mix pieces after the first year’s exposure.


Top row, from worst to best:

Epifanes Rapidclear – The most worn and discolored of the top row bunch. Rough feeling with no shine or gloss.

http://i1285.photobucket.com/albums/a59 ... 250608.jpg

Cetol Marine – Not as badly discolored as the Rapidclear, but little gloss/shine left.

http://i1285.photobucket.com/albums/a59 ... 250609.jpg

Epifanes Clear Spar – Starting to wear in places, some discoloration, some shine/gloss.

http://i1285.photobucket.com/albums/a59 ... 250610.jpg

Coronado Marine Spar – Starting to wear but still good gloss/shine. However this is the only test piece among the varnish row on which the wood began to split or crack as badly.

http://i1285.photobucket.com/albums/a59 ... 250611.jpg

Cetol Marine Lite – Little discoloration. Still smooth with consistent dull gloss.

http://i1285.photobucket.com/albums/a59 ... 250612.jpg

Helmsman Spar Urethane – Still the best of the “varnishes”. Smoothest, shiniest, and the least discoloration.

http://i1285.photobucket.com/albums/a59 ... 250613.jpg

Bottom row, from worst to best:

Control (no finish) – The surface is very rough and the wood has many small splits on the front and bottom.

http://i1285.photobucket.com/albums/a59 ... 250614.jpg

West System (105/206) – The resin coat is completely gone from the sun exposed top and front of the test piece and the exposed wood has begun to split in those areas.

http://i1285.photobucket.com/albums/a59 ... 250615.jpg

Varnish (one coat) over West System – the varnish coat is gone or lifted and peeling on the top and front and the exposed wood has begun to split. Wins the ugliest award.

http://i1285.photobucket.com/albums/a59 ... 250616.jpg

GunwaleGuard and Watco Exterior – Unlike the control and epoxy pieces the wood is not splitting, but the grain is raised and rough.

http://i1285.photobucket.com/albums/a59 ... 250617.jpg

DIY oil mix – The smoothest of the oiled pieces, no raised grain or wood splits, and the exposed wood has not begun to split as on the others.

http://i1285.photobucket.com/albums/a59 ... 250618.jpg

Overall some things are obvious and were predictable. UV exposure is a killer, the top and front edges of all of the test pieces faired much worse that the sun-protected bottom edge. The undersides and drilled screw holes are all still sound (I varnished or oiled the insides of the screw holes)

Lightly sanding and re-oiling or re-varnishing every year or two if stored weather exposed is needed. Once the single varnish coat over epoxy started to go around year 3 it went bad fast and fugly in another year’s time. Multiple coats of varnish might have helped, but refinishing that one would be the most work.

Nothing is soft or punky on any test piece; all of the pieces are still sound and would be salvageable with sanding and recoating. I expect that it helped immensely that all 12 pieces were 3 feet or more off the ground, and were never used in canoe-like applications where rot-hastening dirt and debris can accumulate under the wood (think ends of thwarts, yoke and decks especially).

Sanding and resealing any of the varnish or epoxy coated pieces would be a lot more work than doing so with the oiled pieces at this stage of degradation.

After 55 months of sun, rain and snow exposure my favorite of the varnishes is still the not-varnish, Helmsman’s Spar Urethane.

Of the oils the DIY mix of 1/3 boiled linseed oil, 1/3 spar varnish and 1/3 turpentine seems superior to any of the store bought mixes. Watco Teak would have been a better choice than Watco Exterior, but I used what I had.

(Thanks to friend Dave for providing many of the varnishes used).

For further comparison the one and three year results are below. The amount of degradation and order of preference changed somewhat during the years of exposure.

+++

The one year results:

Top row from worst to best

Sikkens Cetol Marine and Sikkens Cetol Marine Lite. Not terrible, but both show a little more weathering already than any of the other varnished pieces.

Epifanes Clear Spar and Epifanes Rapidclear. Still pretty good, with just a tiny bit of weathering.

Coronado Marine Spar. A bit of a surprise as the best of the “real” varnishes.

Helmsman Spar Urethane. The real shocker. By far the most commonly available and least expensive, and by far the best so far. Straight outa the can.

Bottom row from worst to best:

West System Epoxy. I’m astounded how bad epoxy went in 14 months time without a UV protective top coat. Flaking, cracking and peeling, it looks like wood leprosy.

Gunwale Guard. Also nasty. Although all of the test pieces of scrap gunwale were dry, aged and sanded down to 400 grit the GunwaleGuard treated piece has raised wood fuzz and separating grain.

Control (no finish). Actually better than the gawdful unprotected epoxy or the fuzzing GunwaleGuard.

Watco – Not as good as I thought it would be.

DIY oil mix – Marginally better than the Watco. I’m thinking the oiled pieces need more than a one-a-year light sanding and reoiling.

West System with one coat Coronado varnish. As good as any of the top row varnishes. I’m amazed at the UV protection that a single coat of varnish over epoxy affords.

After 14 months exposure I’m liking Helmsman Spar Urethane, Coronado Marine Spar and epoxy resin with a UV varnish topcoat as the “plastic” protectants, and the DIY oil mix of varnish/boiled linseed and turpentine as the oil rub.

+++

3 year results

It had been my intention to lightly sand and re-oil the GunwaleGuard, Watco and DIY oil mix test pieces, and I did so perfunctorily after recording the year 1 (er, 14 month) results. And then I never quite got around to it again. And didn’t pay much attention to the test panel during year two.

Here’s the 3 year results:

Top row, worst to best:

Epifanes Rapidclear – Faring the worst of the varnishes or urethanes. Flaking off with discolored wood.

Coronado Marine Spar – Went from one of the best at one year to the second worst at 3 years.

Epifanes Clear Spar, Cetol Marine Light and Cetol Marine – Much better after 3 years than the Coronado or Rapidclear.

Helmsman Spar Urethane – Still the surprising winner. As smooth and sound as the day I put it on.

Bottom row, worst to best:

West System Epoxy – Nasty. Most of the epoxy coat has flaked off and what remains is fugly. The exposed wood is actually worst than the control piece.

Control – Bad, but at least it doesn’t have flaking epoxy remnants.

GunwaleGuard and Watco – Better than the control, and a sanding and re-oiling would bring them back to life.

DIY oil mix – Noticeably better than the GunwaleGuard or Watco

West System with one coat Coronado varnish. I am still amazed at the UV protection afforded by a single coat of varnish over epoxy resin. It is just starting to degrade at one end where I was probably a little thin with the varnish coat. I expect if I had triple coated it with varnish it would now be the best of the lot.


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PostPosted: January 27th, 2013, 12:12 pm 
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Location: Lower Saranac Lake, NY
Mike;

This was a larger undertaking with huge consequences for boatbuilders and owners. Thank you for the significant efforts.

Who'd a thunk that the most expedient solution, MinWax Spar, which is available everywhere, would happen to also be the best?


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PostPosted: January 27th, 2013, 1:19 pm 
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:clap:

Thanks Mike, awesome info as always.


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PostPosted: January 27th, 2013, 1:23 pm 
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Location: Freeland, Maryland USA
Charlie Wilson wrote:
Who'd a thunk that the most expedient solution, MinWax Spar, which is available everywhere, would happen to also be the best?


Charlie, some geezer boat builder guy suggested Minwax Spar. The availability and ease of application are attractive. That it holds up well is a bonus.

A lot of things in that experiment were missing or hard to factor.

If this test actually applied to wood gunwales the result of any flex (or paddle scraping wear) in the test pieces was completely missing. I am not a fan of varnished or epoxied gunwales, nor of storing wood gunwaled canoes outdoors and unprotected from the elements.

If the test applied to wood yokes, thwarts and end caps (where I would use varnish, er, Helmsman Spar Urethane at this point) the usual accumulation of dirt and debris that gets trapped against those pieces was lacking. I seal the butt ends of those completely UV protected pieces with extra varnish coats even on a new hull, and of course any newly cut ends drink in sealant. Those cross pieces seem the fastest to rot and I believe many (most?) new canoes come from the manufacturer with insufficiently sealed thwart and yoke ends. That seems a sad area to cheap out on a built, since the first coat of varnish disappears into the end grain.

Also missing from that experiment was good quality control in the varnish thinning schedules. I tried to follow the recommended thinning schedules as best I could, but was working with very small batches of each varnish and the proportions were probably inexact. I did increase the amount of turpentine in the first DIY oil batch, and did not thin the GunwaleGuard or Watco for initial applications.

Here’s the question though – what should I do with the 12 test pieces now? They are all marked on the bottoms indicating the varnish or oil used. I don’t want to burn them in the woodstove or campfire. Maybe give them a decent burial under a few inches of soil and dig them up after a few months to see how they faired.


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PostPosted: January 27th, 2013, 3:28 pm 
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Location: Atlanta
West 105/207 might have done better without a varnish topcoat. It has some UV protectant in it.

I have some spruce gunwales protected with 105/205 and a urethane "spar" varnish, and they have held up well over about 8 years of river trips.

I will have to try Minwax Spar. I've used Minwax 209 clear oil for furniture for many years with excellent results indoors. It also stands up tolerably as a paddle grip treatment.


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PostPosted: January 27th, 2013, 6:13 pm 
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Location: Freeland, Maryland USA
ezwater wrote:
West 105/207 might have done better without a varnish topcoat. It has some UV protectant in it.


Yeah, but I had no 207, and I believe it needs a pump for a different ratio than 205/206.

ezwater wrote:
I have some spruce gunwales protected with 105/205 and a urethane "spar" varnish, and they have held up well over about 8 years of river trips.


I have an old Independence that I rebuilt with DIY wood gunwales at least 15 years ago and I have only re-oiled the gunwale exterior a couple of times. But that canoe is stored inside. Despite a desperate lack of indoor rack space I cannot bring myself to store a wood railed canoe outside.

Does your spruce railed boat live inside or under cover?


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PostPosted: January 27th, 2013, 7:42 pm 
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I had a MR Compatriot that came with spruce rails, and it did not too well stored outside under a tarp.

I have a MR Synergy ww tandem where I replaced the clunky ash thwarts with sitka spruce thwarts. Those are the ones I referred to. That boat is stored in the carport, where it is sheltered from direct rain. The custom thwarts are still OK. They could probably use a cleaning, sanding, and re-varnishing.


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PostPosted: January 28th, 2013, 8:20 am 
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ezwater wrote:
I had a MR Compatriot that came with spruce rails, and it did not too well stored outside under a tarp.


Covers on outside boats, at least “unbreathable” covers, may do more harm than good. I think it can be similar to storing the boat inside a greenhouse, trapping moisture/humidity around the hull. Plus leaving an unbreathable tarp in direct contact with the hull can make plastic boats slimy and discolored and do worse to composite hulls.

UV is a big enemy of wood trimmed canoes stored outside, especially the outwales which take the most exposure, but constant moisture may be as bad or worse.

I have a Florida paddling friend who has (had) a couple of wood trimmed canoes. Those boats did OK when he lived in Maryland, but after moving to Florida the extreme humidity began to degrade all of the woodwork, including the thwarts and yokes, in just a few years.

He stores his canoes under a large pole barn. They are completely UV protected in storage and on a rack system with plenty of air circulation. The only difference was the more constant high humidity.

(Well, that and him doing zero maintenance on any of his boats. He also had a very nice woodstrip solo tripper that two consecutive Pennsylvania friends had owned and paddled for a decade or more. The last time I saw the stripper it was closer to compost than canoe)


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PostPosted: January 28th, 2013, 8:53 am 
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One more note on the oil & varnish test. Looking at those test pieces I noticed that on several of the varnish coated sections there is obvious degredation at the ends. Not just the open-grain butt ends, but at the outside edges of wood length.

That was the most obvious starting point of varnish failure in previous year’s inspections, and on the test pieces that have some finish remaining it is still apparent.

Image

Image

I was very careful in hanging the freshly varnished test pieces to dry after each coat, using a nail in the screw hole to handle them, and I reversed the direction they were hanging after each additional coat of varnish. If anything the varnish coats should have ended up thicker towards the ends.

I didn’t really need more convincing – it’s the open-grain butt ends you have to watch.


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PostPosted: January 28th, 2013, 4:21 pm 
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On my spruce thwarts, I actually epoxied short strips of FG over the cut ends. I epoxied plastic soda straw liners into the screw holes, and I epoxied FG slips on the thwarts, around the screw holes. All this was because of my anxiety that moisture would get in at these locations and cause wood expansion and rot.

Wood by its nature wants to pass moisture along its length, and it's hard to stop it.


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PostPosted: February 2nd, 2013, 1:47 pm 
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Thanks for posting this info again, Mike.

As you said, some of your results were quite predictable. Epoxies without UV blockers fair poorly under prolonged, continuous UV exposure. It may take 6 months or more of constant UV exposure before they start to go bad, however. Of course, most folks don't finish the wood on their boats and then set them out in the elements for years on end, so some of the treatments you used would have fared better in real-world usage.

I am not particularly surprised that a polyurethane proved to be more durable than a traditional varnish finish. I have used the Minwax Helmsman Spar urethane on livery canoes that I help maintain. I think it is a good choice for boats that are not going to see much preventative maintenance. At least in my hands, I seem to experience more runs and sags with the polyurethane than I do with conventional varnish though, and I still think that a carefully applied traditional varnish finish has a depth and luster that is not matched by polyurethane.

I have tried a variety of oil finishes over the years and some of my experience mirrors your results. I have not been particularly happy with Watco exterior. If I am going to use Watco I use either the Teak oil (which contains some varnish) or the conventional interior Watco oil. I haven't seen any problems using the Watco interior oil on wood trimmed boats that get only periodic UV exposure.

I think Gunwale Guard sucks. Better than nothing, no doubt, but it has no merits relative to boiled linseed oil concoctions or Watco oil.

I suspect that your home-brewed "oil" mixture fared better than Watco exterior because you mixed varnish in with it.

I have found Tung oil finishes to be somewhat more durable and somewhat nicer-looking than Watco oils , including the Teak oil.

The very nicest results I ever got with a penetrating oil finish was using Deks Olje Number 1, but only if it was applied according to directions. Deks can be applied in multiple coats (up to 8 or more) within a few hours time and if done properly you can achieve a depth of luster that I at least cannot obtain with Watco oil. If you try doing the same thing with Watco oil you wind up with a gummy mess.

Oil finishes are definitely not an "apply once and forget about it for a few years" proposition. Oil finishes work very well for those willing to reapply oil several times a year, and reapplication is much simpler than it is with a varnish or urethane finish gone bad. On the other hand, oil finishes are probably a poor choice for those disinclined to give their boats much maintenance, especially if they see much outdoor storage or use.

In future, I plan to bright finish wood trim by first applying a clear coat epoxy such as System 3 Clear Coat (which I hope will seal the grain of the wood better than varnish alone) then cover it with at least three coats of varnish (or polyurethane). It will be interesting to see if the epoxy adds durability to the finish.


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PostPosted: February 2nd, 2013, 6:59 pm 
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pblanc wrote:
Of course, most folks don't finish the wood on their boats and then set them out in the elements for years on end


Pete, it is a sin to treat a canoe that way. On the other hand two of the canoes I’ve rebuilt, the Independence and an Explorer, were treated just that way, actually resting on the ground until the gunwales literally rotted off. Re-railed, with new seats and thwarts, both are still going strong today.

Both were free, so I have a soft spot for sinners.


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PostPosted: September 19th, 2013, 8:44 am 
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Great stuff, Mike. You seem to have a real passion for experimentation!


The comment below puzzles me, though. I don't see any MinWax in your tests. Did I miss something obvious?
Thx

Charlie Wilson wrote:
Who'd a thunk that the most expedient solution, MinWax Spar, which is available everywhere, would happen to also be the best?

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PostPosted: September 19th, 2013, 9:25 am 
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The Helmsman Spar Urethane is made by MinWax.

http://www.homedepot.ca/product/gloss/911388

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PostPosted: September 19th, 2013, 9:55 am 
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wotrock wrote:
Great stuff, Mike. You seem to have a real passion for experimentation!


Wotrock. I enjoy working, and playing, in my shop. The “play” and experimentation helps slow me down. That in turn provides pause to think about the proper order of sequential steps, best technique and application and the most detailed prep work.

Prep work, especially with varnish or epoxy, is 90% of the job – the actual varnish or epoxy application usually takes minutes. And, of course, the better the prep work the less subsequent effort is required.

Sometimes going slowly gets the job done faster.

Splake wrote:
The Helmsman Spar Urethane is made by MinWax.


Yup, that’s the stuff. I was impressed enough that I am using it on a batch of paddles I am refurbishing.

http://www.myccr.com/phpbbforum/viewtop ... 0&start=15

OK, full disclosure. I am using it because I had a nearly full can of Helmsman Spar Urethane in the shop and didn’t want to spend $35 on a quart of spar varnish.


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