Replies

1. 
   EdHarrow | Jul 24, 2003 04:25am | #1

   In general, wet sanding should be fine, but four coats is a bit thin, especially if you did much sanding between coats.  Scuffing with a 3M pad should be sufficient to provide enough "tooth" for the next coat.  Starting from a bare surface, for an item to be in the sun and weather, I'd figure 8 coats.  Also, if not coated on all surfaces, moisture can work in behind the varnish and start to lift it.  Many wooden boat folks swear by Clear Penetrating Epoxy Sealer by Smith and Company.  It tends to seal the wood and limit moisture problems. 

   There's a great book on the subject by two woman who've done more brightwork than most of us will ever see.  I think the title is simply "brightwork", but I'll check and post it later. 

2. 
   swines | Jul 25, 2003 12:10am | #2

   We just got done with varnishing my 1941 Chris Craft Custom Runabout.  The deck has 14 new coats, and the topsides have 4 new coats applied over the existing 12 coats. 

   I would suggest that you use a quality marine varnish and not use varnishes generically labeled as "spar varnish."  

   Here's the deal with marine varnishes.  They protect wood as follows.  The good ones have UV inhibitors in them.  This keeps the varnish from breaking down from UV light outdoors.  The UV inhibitors actually float to the top of the varnish as it cures.  The more coats you put on, the better to protect the very first coat applied onto the wood. 

   Varnish breaksdown from prolonged UV.  First, the top coats begin to turn "milky" and the varnish no longer looks crystal clear.  If this is allowed to continue without revarnishing,  the very first coat applied on the wood starts to breakdown and that's when the varnish begins to "checker" and then peel.   At that point, it's too late and all of the varnish has to be stripped off.

   If you are going to try and use a wood piece outdoors with varnish, I would suggest that you first coat all sides with Clear Penetrating Epoxy Sealer (CPES) made by Smith and Company (http://www.smithandcompany.org).    This will seal the wood completely and provides a base for the the varnish to adhere.  If the varnish is put on during the first 48 hours after treating with CPES it will be "glued" to the wood as the CPES continues to dry.

   If you only rub on varnish or sand it off, you will not get the UV protection built into the varnish because it has not been applied thickly enough for the UV protectorants to float to the surface, or they will have been taken away by the sanding.  The only way to get lasting outdoor protection from varnish is to apply multiple coats & build it up.  If you don't do that, don't expect the varnish to last any length of time as it is not being used correctly.

   Quality marine varnishes are made by: Interlux, Pettit, Detco, and Epifanes.  Most wooden boat restorers seem to use either the Interlux or Epifanes products.  We tried the Detco on my boat as a test - we'll see what happens in about 4 years....

   
   

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   Edited 7/24/2003 5:20:21 PM ET by ARTPILE

1. 
   DavidP52 | Jul 25, 2003 03:45am | #3

   I agree, you don't want to scratch the varnish gloss with sandpaper. That causes minute crevices that accelerate UV deterioration and aid in water penetration.

   I don't understand why you'd want a rubbed varnish appearance for outdoor furniture anyway. Ok for inside, but not out. Note that the Bruce Hoadly book indicates that at least 3 full coats of varnish only begin to seal the wood. 3 isn't enough and to be safe, you need 6 but I've often gotten away with 5 because we always add more later.

   RE; spar varnish, it had lower dissolved solids and cures much less hard and is less durable in the ways landlubbers would want. It was designed for spars (masts) which take a lot of impacting and denting, so the varnish is quite soft and stays soft for a long time. It also stretches as wood wets and shrinks without the severe checking that occurs with harder varnishes. Anyone who advocates sanding an polish this stuff doesn't know what they're doing.

   Epoxy is the only truly water proof finish, followed by linear urethane (not poly).

   Boat captains say Epiphanes is the best, but Ive never used it. Pricy at around $40 quart.

   Edited 7/24/2003 8:49:30 PM ET by boatman

   Edited 7/24/2003 8:56:54 PM ET by boatman

1. 
   user-302616 | Jul 25, 2003 05:05am | #4

   How long do you expect a 6 coat single part marine finish to last in the outdoors? How long for a 2 part marine polyurethane varnish? I get a lot of requests for outdoor projects but I am always very cautious as my finishes dont last more than 2 years. Wonder if you guys are able to get anything to last longer than that.

   Shane

1. 
   EdHarrow | Jul 25, 2003 06:55am | #5

   Brightwork.  Rebecca Wittman.  Photos alone are fabulous. 

   "Poppie" would use nothing but Man-o-War spar varnish on whatever it was.  Inside, outside, furniture, whatever.  Dad likewise (Even the inside of the garage doors, LOL).  Today there are many more options, and as I sit here I'm wracking my brain trying to remember what I used on a boat a month or two ago - ahh, Deck's Ole (sp?).  Interesting stuff.  Seemed more forgiving than the varnishes/polys with which I've worked before.  Anyway, it was what the guy wanted, and he was buying.

   Getting two years, on an exterior "working" surface seems a reach to me, tho the folks that use CPES claim to do better.  Smith also makes a "varnish" he calls five-year clear, or something close to that.  Reports seem good, but I understand that once it starts to go it must all come off...

   A party on the WoodenBoat Forum has commented that he doesn't think varnish over CPES looks as good as over untreated wood.  I can't comment on that.

2. 
   DavidP52 | Jul 25, 2003 07:29pm | #6

   Don't know about other places but there isn't anything that would last two years in Florida or anywhere else with a lot of sun. Look what sun does to your car!!! You add one new coat each year in a moderate climate and that way you are replacing the erroded surface before it it is too far gone. It's easier to simply cover it up when your not using it. Saves a lot of grief. Took my wife about 30 mins to make a canvass cover for a teak table. Now it only needs refinish every two years and that job takes an hour.

1. 
   DavidP52 | Jul 25, 2003 07:46pm | #7

   Here's the thing about varnishes in wet environments. Wood is dimensionally unstable unless you can completely seal it. That includes all joints. It only takes a tiny amount of moisture to penetrate and cause it to swell. We learn this on boats the hard way. When the wood swells, the finishdevelopes hundreds of cracks, so the deterioration rate procedes exponentially. This is why nobody can keep a finish on doors - too many unsealed joints. I've got a couple living room end tables with urethaned tops that just keep on checking no matter how many coats I put on them - the undersides aren't sealed and can't be.

   Marine varnishes are formulated to cure "soft", they stay rather pliable so that they can expand with swelling and minimize cracking. They tried the epoxies and urethanes, which is too strong to crack. Instead it breaks away from the wood in sheets and starts to peel bit-time. Then just try to strip it off!! Whatever you do, don't use urethanes on outdoor stuff because it is unlikely that you can seal the wood completely unless all joints are MADE with epoxy glue.

   An old myth says that marine varnish "breathes". That's nonsense, of course, but it does stretch and cannot be rubbed out very well unless it is really aged well. Use satin, if you want a duller finish, tho satin is considerably less durable.

2. 
   RdrgzDesign | Jul 25, 2003 10:58pm | #8

   Hi -

   Excellent information! I knew you would be able to shed some light on the situation. It seems that Lon's technique is meant to be limited to interior use, although he never says as much in the article and the use of spar varnish could be misleading - it was for me. As I've done some further research on this subject I've run across a product - Penofin - that seems to fit the bill for me. This client definitely doesn't want the film-type finish look. So an oil is attractive, which is what Penofin is. Thanks again for the education on spar varnish. Understanding the mechanics of it definitely helps me.

   -R.