Author Topic: Varnish vs. Polyurethane  (Read 9672 times)

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Offline Dave Blake

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Varnish vs. Polyurethane
« on: May 17, 2010, 05:47:11 PM »
I'm nearing the varnishing stage for my brightwork (all spars, mast, interior and usual deck fittings like hatches, grab rails, coaming etc.  I've heard the pro-varnish arguments:  more flexible, easier repair, but the cost is a little off-putting: $83/gallon for Z-Spar Flagship varnish.  Polyurethane "spar varnish" like Varthane and others runs less than half that.  Anyone have favorable experiences using the polyurethanes for brightwork?  How about using polyurethane inside the cabin, and traditional varnish outside, on parts directly exposed to the sun?

Dave

Offline Paul Riccelli PE,NA

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Re: Varnish vs. Polyurethane
« Reply #1 on: May 17, 2010, 06:00:30 PM »
Polyurethanes dry fast and cure hard. They are less flexible, but on epoxied surfaces this isn't very important, as the epoxy locks the wood down (assumed encapsulation). The ability to apply three or four coats a day is appealing too. The good stuff will cost just as much as good varnish. I'm paying $130 a gallon for poly. Be sure you get what you need, as the polys are much clearer and have less color then the real varnishes.

Varnish isn't as durable, nor as glossy as polyurethane. It's easy (relatively) to repair and will flex with the wood. The good varnishes will add a lot of color to the wood and they can take what seems like a life time to fully cure.

Polyurethane will out preform even the best varnish, in gloss retention, UV protection, etc., some times by 2:1, but mostly by about 50% as much better. In the sunny Florida climate, good varnish will last a year, before you need to make repairs, polyurethane about 18 months. They both will still look good at these time intervals, but damage will begin to show and if you don't "catch it" when you can, you're screwed and the whole finish and likely some wood will need to be removed, restored and refinished.

Offline Dave Blake

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Re: Varnish vs. Polyurethane
« Reply #2 on: May 18, 2010, 07:58:21 AM »
Paul:  The poly you refer to that allows 3-4 coats per day is water-based, correct?  What about oil based polys like Varthane Spar urethane?

Dave

Offline Paul Riccelli PE,NA

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Re: Varnish vs. Polyurethane
« Reply #3 on: May 18, 2010, 04:31:24 PM »
I wouldn't recommend any of the water born clear coatings, some of which are partly polyurethane. Most of these water based systems are in their second generation and much better then the first products that showed up over a decade ago, but they still suck.

The word "spar" in the name of the product usually means coloring. A "spar" urethane would be regular urethane with amber color added.

The polyurethanes I'm using dry in minutes and can be sanded in hours. I don't recommend these for novices, as they literally dry while they come out of the gun, so some skill and considerable prep is required. You can't roll and tip these finishes, though there are some brands that permit slower activators and wetting agents.

Offline Dave Blake

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Re: Varnish vs. Polyurethane
« Reply #4 on: May 18, 2010, 07:52:12 PM »
Paul:  My brightwork is all epoxy encasulated.  Would you have a problem using an oil based poly like Varthane's Spar urethane or Minwax's Helmsman spar urethane?  IO don't think I'm up to the pro stuff you use!

Dave

Offline Paul Riccelli PE,NA

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Re: Varnish vs. Polyurethane
« Reply #5 on: May 18, 2010, 08:49:36 PM »
Minwax products suck, don't even think about using them, unless it's aunt Millie's rocking chair and you don't like her all that much. Valspar products I don't have much information about, just that it's also a DIY type product and probably about the same as the Minwax stuff (I'm assuming).

System Three polyurethane is getting popular. Epifanes PP varnish is well liked. Pettit Z-Spar and Interlux Goldspar or Schooner are also well used. Bristol Finish is also very good and I use it fairly often (they're local to me)

The home owner stuff does a decent job, but you'll be recoating it sooner and damage can occur faster with the Minwax type products. Most of the real marine clear coatings will cost about $20 to $40 a quart and some of the fancy stuff can cost a lot more. Which you elect to use is more about comfort level and experience.

Offline Dave Blake

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Re: Varnish vs. Polyurethane
« Reply #6 on: May 19, 2010, 12:05:07 PM »
Thanks, Paul.  I talked to a local boat guy today.  He uses Petitt Captain or Flagship.  He felt that 3 coats over my 3 coats of epoxy were enough for a trailered boat kept in a garage.  What do you think?

Dave
« Last Edit: May 19, 2010, 12:10:21 PM by Dave Blake »

Offline Paul Riccelli PE,NA

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Re: Varnish vs. Polyurethane
« Reply #7 on: May 19, 2010, 10:12:04 PM »
Three coats leaves no margin for error, wear or UV degradation. If the boat is kept indoors and doesn't have any sunlight (including reflected) touch the surface, yes, 3 coats will do.

It doesn't take much time at all to damage a coat or two of varnish. One missed step, one dropped what ever and you've now got a direct path to the stuff under it, which you really don't want to have to fix or refinish.

I consider 3 coats a tease. The bottom line with clear coating anything and the outdoors, is film thickness with effective UV inhibitors. The more you got, the better off you'll be. 3 coats is like a hot fudge sundae that has just a drop of hot fudge, slithering down the side of a scoop of vanilla.

Offline Terry Peterson

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Re: Varnish vs. Polyurethane
« Reply #8 on: May 20, 2010, 04:22:14 AM »
Paul, Please remember that some of us are on diets trying to lose a bit of weight.  Your hot fudge sundae comparison lead to me eating a dish of the stuff at 4 am.  :P  Actually after reading your comments I will head to the shop later this morning and add a couple more coats to my oars and tiller handle.  Those are the only bright work I on my boat.  Got lots of varnish left, don't take much for 2 oars and a tiller handle, so may as well make use of it.
aargh Matey!

Offline Dave Blake

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Re: Varnish vs. Polyurethane
« Reply #9 on: May 20, 2010, 06:52:43 AM »
Paul:  Thanks for all the great advice!  I've checked out Bristol finishes, and although the price is huge, the advantages may be worth it.  Is it true?  No sanding between coats?  One hour to recoat?  Seems to good to be true!  Their website claims 133 sq. ft/gallon with 6 coats.  Can I brush it on, roll and tip or must it be sprayed?

Sorry for all the questions but before I invest almost $400 for 2 gallons I want to be sure I know what I'm getting!

Dave

Offline Dave Blake

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Re: Varnish vs. Polyurethane
« Reply #10 on: May 20, 2010, 08:44:20 AM »
How about Epifanes Rapid Coat?  No sanding between coats, but dries a bit slower.  Is it glossy enough?

Dave
« Last Edit: May 20, 2010, 09:14:38 AM by Dave Blake »

Offline Paul Riccelli PE,NA

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Re: Varnish vs. Polyurethane
« Reply #11 on: May 20, 2010, 10:09:20 AM »
Bristol isn't the easiest finish to apply. Getting the right speed activator and other curing agents mixed for the local environment can be daunting. It does produce a really nice finish, but you have to pay for it both in cost and application skill.

In fact all the multi part, fast drying stuff will challenge the novice. There's a lot to go wrong and not much time to fix it. Also, never believe the manufacture's suggestion about coverage. Their coverage figures come from "in lab" testing with a perfectly controlled environment. You'll never be able to apply the finish as uniformly, nor in the same conditions, so it's best to knock at least 25% off any coverage claim.

Most will be more then satisfied with a single part polyurethane, which dries fairly fast. In warm weather you can get a few coats per day. Humidity slows things down with these types of urethanes, but they still dry fast compared to regular varnish.

Leave the fancy stuff for the mirror finish work, which requires perfect surface prep. So, unless you can make flawless surfaces, that these high tech (and costly) finishes can really show off, you'll be better served with a slightly less fancy coating that is nearly as durable and shinny.

Offline Dave Blake

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Re: Varnish vs. Polyurethane
« Reply #12 on: May 20, 2010, 11:12:05 AM »
Paul:  Does Epifanes Rapid Coat fit the bill?

Dave

Offline Barry Pyeatt

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Re: Varnish vs. Polyurethane
« Reply #13 on: May 20, 2010, 12:59:26 PM »
If you live and keep your boat outdoors in the deep South.  The UV deterioration is so dramatically higher than in the North or even middle reaches of the country.  Hawaii and Florida are two areas where the degradation in the finish is much more dramatic.  I have Used the Varathane products since their introduction and never had issues with them in use for Marine applications.  They have exceeded my expectations by a considerable margin.  Their UV protection is high and effective.  Application isn't nearly as critical as "Marine products".  Nor does it need to be redone as frequently as "Marine Varnishes and Marine Polys" 

The quality of the finish is only as good as the preparation that goes into it.  If you want a flawless finish, you need to have flawless preparation.  Not many are capable of applying a mirror like finish in a home built situation.  Very few have the lighting that is needed to expose the flaws or are willing to go the extend of primer coats and filling and preparing to apply a mirror like finish.   

The Marine products are outstanding for the most part, but you pay a real premium for a very specialized market product.  Many of them not realistic to consider applying yourself.  Most are designed to be used on boats that live in the water exposed to the elements 24/7.  Not many of these need that kind of protection. Stored in a garage or protected from the elements except when it is being used is an entirely different matter.

 I know a lot of boat owners who simply are not willing to put the work into maintaining the high gloss finishes and are so worried that they might scratch it that they don't get any use or enjoyment out of their boats. I enjoy maintaining brightwork and the warmth and character of woods.  But I save the Grand Piano finishes for furniture that lives inside and isn't ever exposed to the elements.  I use my boats, enjoy them and take the time to maintain them so that they are servicable for many years.  I take care of normal wear and tear, don't fret about a ding or scratch that might mar an otherwise perfect looking finish.  I finish so it looks great at 20 feet and still looks good at 5 feet.

The Marine Specific Finishing  products simply don't provide a good return on investment for me on this type of boat.  I find that there are plenty of lower cost finishing products that provide superior returns on effort, cost and ease of application and are easily maintained as well.  Products that are subjected to 24/7 to the outdoors environment in tough places to live.  And they hold up well.  But I don't try to take interior furniture finish or paint products and expect them to hold up on a boat.  They simply don't. A good exterior oil based  semi-gloss porch and deck enamel will provide good protection, same with a good single part exterior polyurethane will hold up well for many years with an occasional touchup. And they ae far more forgiving in application.  A good coat of wax over them, buffed out and they can look great and perform great as well.

I personally would rather see a well enjoyed and well used boat with a little care out sailing than seeing a lot of the really nice boats never really used or enjoyed for fear they will not look good.  But I do agree that a little extra effort in finishing bright work is well worth that effort in personal satisfaction. 
Weekender, Spiritwind
Mukilteo, Washington

Offline Dave Blake

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Re: Varnish vs. Polyurethane
« Reply #14 on: May 20, 2010, 08:20:46 PM »
Barry:  I share many of your opinions.  My boat will be trailered, stored indoors and sailed in Wisconsin...not exactly the Sun 'n'  Fun capital of the world!  I'd use a Varthane product, but what attracts me to the Epifanes product is the fact that there is no sanding between coats!  This is a huge timesaver considering the fact that the interior of my boat is bright.  I hate sanding.

Dave