Urethane vs Varnish

Sorry for the beginner question, but my hardware store insists that Marine Spar Urethane is the same as Spar Varnish. Are they interchangeable terms? I am preserving an old Edwin Monk kit runabout, and would prefer the "fixablity" of varnish in the future on the mahogany deck. Thanks for any advice.

 

Bristol Fashion varnish

My experience long ago with 'urethane varnish', specifically clear Algrip was far less than satisfactory. Primarily it did not bond to the wood as good as diluted first coats of regular varnish, and seemed to be less flexible. When struck by some object, a whole patch area would lift from the wood substrate.

I later tried a varnish I was much happier with by the name of Bristol Fashion, which was a mixture of tradition varnish with some urethane mixed in for durability. This was exception I thought. But I don't think they manufacture it any more. This was 30 some years go, just as Algrip was coming on the market.

 

Thanks Brian. I really want to be able to fix any minor "incidents" with more ease in the future. That's why I want to use varnish, vs. polyurethanes. My problem is that in a small town, there are not a lot of choices, and I am just not buying that the because it has the word "urethane" doesn't mean that it has the negative qualities of polyurethane products, even though it is "marine urethane". I like the quality of varnish that allows for an easier fix of a blemish.

Since most of this boat is the same as it was in 1957 when it was built, I am trying real hard to be as authentic as possible in this preservation, and at the same time trying to maintain domestic bliss by not spending more time working on the boat than other "high priority" house projects.

By the way, I am failing miserably in that aforementioned altruistic goal. That's OK. It turns out that working on this old wooden boat has done more for my sanity and peace of mind than I ever could have imagined. But I am probably not alone in that sentiment.

 

Marc

I was doing some marketing for a timber coatings company that had developed an exterior finish for timber.

We had it tested at the Materials Testing Laboratory where they use a weatherometer. This subjects the finish to humidity, dry heat, water sprays and cold over a period that is supposed to similate about ten years of weathering.

We tested the coating against about ten other coatings and the thing that surprised me was all the coatings that were labelled marine finishes came out on the bottom and in fact blistered quite badly.

It seemed to me that one should not take much notice as to what is written on the can.

 

Thanks, Poida. Interesting scientific results, and probably will generate some discussion! What appeals to me about using true varnish is that scratches or dings can be lightly sanded out and touched up. But, as I said in the first post, this is all new to me, so most of my marine varnish vs. polyurethane knowledge has been gained by reading old posts here and researching on the internet.

 

I've been working on boats (my own and other people's) since the 1970s. Early on I used something called Doc Callahan's "Chilled Varnish" and always had good results (spendy at $ 15/quart back then). In August of 1975 I had "wooded down" the mahogany cabin on a 30' pleasure boat and was ready to start applying varnish. But no one in Seattle, Washington had any (run on varnish due to nice varnishing weather) and I didn't want to leave the cabin that way for the week minimum until some store got an order in. So I went to a lumber yard a few blocks down the road from Doc Freeman's to see if I couldn't come up with something. Came across a product called McClusky's "Man-o-War" spar varnish. Asked the guy at the sales counter if he would open a small can and let me feel/smell it. Felt good; smelled like the real stuff (and a lot cheaper at $ 3/quart back then). I've used it ever since with consistently good results. As long as it is applied as one should apply varnish it lasts well. One "renewal" coat a year is generally OK (lots of heatr/direct sun may require two). Most lumber yards in North America carry it and the price is reasonable. Have never tried the UV version - the regular has worked just fine.

Ron Fossum

 

whats the point, Im going to use polyurethane because ,,,,,you re do every few years anyway

 

Thanks for the feedback. Now that you brought it up, I remember using man o' war spar varnish on a wood project many years ago, and it was almost bulletproof. So, I have a plan. (Always good for a laugh)

I will invest in a good custom canvas cover, practice careful trailering, and have already arranged indoor storage for "my other wife" over the lovely Wisconsin winters. By doing this, I hope to put more time between the strip-to-the-wood-and-start-it-all-over-again process. But that's part of the "wooden boats need more maintenance" that I know I've gotten myself into--willingly and enthusiastically.

I just think that if there is an accidental ding here or there, true varnish would outperform polyurethane in terms of being able to patch over it.

Meanwhile, I am down to bare wood on the deck, and am about to give it a little naptha spongebath to see what I missed. Then, it's on to the start of the staining.

Again, thanks for all the advice. You don't know how much it is appreciated.

 

polyuethane is harder than varnishand in most cases more durable,,,time are a changing, the key for boats is UV portection,,just puchased 1 gallon of VARATHANE brand spar urathane for47 bucks ,outdoor with UV and weather protection oilbased clear gloss,in 3 to 5 years I will reapplie,longliner

 

Question from a picture framer

Hello,

We are picture framers in Berkeley CA. I need some advice and a boating forum seemed like a likely place. We have a customer for whom we had built and sold, 3 frames made from oak and stained by the supplier with a water based stain. We told the supplier that we needed a coating for an outdoor installation of the frames (they hold tiles). The frame maker sent them back with a Spar Urethane matt finish coating. The frames failed within two weeks on the client's deck in foggy weather. The mahogany stain bleached white and the surface began to crack. We sent the frames back to the manufacturer. They are sanding them down and refinishing them with the water based stain. We will provide further coatings.

I need a recommendation for a UV coating and something to make them somewhat water resistant. They can be glossy if necessary and the customer understand that he will need to coat them periodically depending on the weather. Should I be looking at a UV spar urethane and then an epoxy coating? I read this thread and am still confused.

Thanks for helping someone out of your industry. I figure if you can protect boats, you would know how to protect an oak frame subject to fog and rain.

 

I built and installed a mahogany swing on my front deck. I coat it with tung oil once a year. After winter I wash the swing with detergent, water, and a stiff nylon bush. after dring I then apply the tung oil, usually two coats.... still looks like new. i have found that wood that is sealed with varnish or poly that is exposed to sun and rain usually yellow and start peeling after a short time.

 

This subject is well covered in a number of locations, but there are some misconceptions.

Your finish failure should be examined to determine why it failed, rather then just having someone put more of the same back on it.

Typically, most stains now are not just stain, but also a sealer, which can dramatically defeat the ability of a finish coating to get a good grip on the wood. The finish grips the stain instead and is solely dependent on the stain's ability to grip the wood, which is questionable at best in most cases.

If you want a finish to stay stuck, you need much better control over it's application. Most furniture builders haven't the foggiest idea how to achieve this, in a marine or severe exterior environment.

Even if they sand down the frames, the pores of the wood will likely still be sealed with a crappy, water based stain/sealer. The first thing you need to do, is find out what products(s) specifically they've used and if these are well rated for your application (doesn't sound like it). Then you can make a reasonable assessment about which path you'd like to take.

As far as clear finishes on wood, you have several choices, from a very traditional but not very durable oil to a very hard, man made linear polyurethanes, which is quite durable. Each has it's own good and bad points to consider, so gather up the product information and get back to us.

I have no issue with the urethane, but they need to be applied properly and maintained or it'll be the devil to pay if it's "gone too far". The more traditional alkyd varnishes, are far easier to repair if necessary, but aren't as durable as the harder LPU's. The Dutch oils are a joke in regard to durability, but are very easy to apply and keep up, though you will not get a sheen, regardless of how much you use.

Tung oil (the main ingredient in Dutch oil) is a much better choice then the more common linseed, which blackens with time and UV exposure. Again, these oil finishes don't really protect the wood very well. The wood will still burn and "move" from environmental changes (humidity), which in a lot of things isn't good (joints open, wood splits, etc.). Scrubbing with a brush, just makes a wash board out of most woods, as the brush removes the burned softer wood, leaving the hard winter growth rings standing proud.

From a technical stand point there's a huge difference between marine spar urethane and spar varnish. Urethanes are harder, glossier and more durable, especially if a true LPU. They are also hard to apply well, especially if a WR-LPU and can often be too hard and brittle for some hardwoods, as Brian's experiences suggested. Spar varnish, is typical a real alkyd varnish, usually with modifiers and UV inhibitors added.

As a rule the word "varnish" no longer means an alkyd, but is representative of all clear finishes, no matter what it's made from. This is likely why your hardware store guy is saying what he is.

Again find out what they're using on your frames and post the brand and product name, so we can know precisely what you're dealing with. Given the previous attempt by your supplier, I'd be very hesitant about sending it back for them to screw it up again, but that could just be me.

 

I agree with Par, and I have not found any water based stains that are really suitable for outdoor use. Best to start with bare wood, apply oil based stains and than min seven coats an exteiror grade oil based finish. I have found the "Man-o-War" brand works well.

The problem you have in California is that the solvents in oil based stains are considered pollution generating substances, so you may have to go to a specialty supplier to get it. You might consider going to an well equipped art supply store and mixing your own finish. Also, even with costly marine finishes, it is normal to recoat every six months if you want it to look good all the time.

 

The problem is not how it goes on or lasts it is what happens when you have to renew it or stip it then poly is bad news

 

I disagree, the issues are all interconnected. "how it goes on" and how long it lasts are primary considerations, while having to strip it off means you've received unexpected damage or have neglected the finish, which isn't the fault of the finishing product.

It is more difficult to fix and repair the urethanes, but not imposable, especially if you have a regular maintenance routine.