Replies

1. 
   sailalex | Dec 29, 2003 04:17pm | #1

   Reed, I use varnish a lot on boats but I am unfamiliar with that brand. There are a lot of varnishes that are called "spar" varnish that have never seen a spar; I think they use that term to enhance the "outside" qualities. I would suggest going to a marine store, if there is one in your area, and select from those manufactureres who regularly sell to boaters. My all around favorite is Interlux Schooner 96 or 95; it is a beautiful finish and lasts as long as any. Epiphanes is a bit more durable and thicker but after you get the hang of using it, it is outstanding. Both of these varnishes are not inexpensive (about $25-30/quart) A thinner but very popular varnish among boaters is Captains Varnish; it is cheaper than the other two, doesn't have the wear resistant qualities of the others and is easy to apply. Also, it is generally available through non-marine retail stores. Hope this helps.

   BTW, for outside use, plan to recoat (3-6 coats) at least once a year depending on your weather.

1. 
   JBD | Dec 29, 2003 05:32pm | #2

   Extensive studies have proven that the best spar varnish alone will not survive near as long as if you varnish over an epoxy sealed surface first.  I too am a boatbuilder, and this step is not only well worth it, but will save on coats of finish because the epoxy is 100% solids.  Two coats of epoxy, sanded, and one heavy (preferably two, normal coats) coat of spar varnish will outlast varnish alone by a huge margin.  Epoxy alone is no good - sunlight will damage and blush it.  Epoxy is hard, and Varnish is elastic - good combo.  I use WEST System with the 207 special coatings hardener for coatings of exterior ply, but others like System Three will work well too (non-blush formulas).  Look up http://www.westsystem.com  and find their articles on coating.

   - JB 

   "The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)

   http://www.pbase.com/dr_dichro

   
1. 
   sailalex | Dec 30, 2003 04:25pm | #7

   Perhaps you can help me understand this:<<Extensive studies have proven that the best spar varnish alone will not survive near as long as if you varnish over an epoxy sealed surface first. >>

   I always considered that what we have here is man applying varnish and sun taking it off. If you agree that epoxy has no resistance to sun without varnish then just a coat or two of varnish is only a coat or two of varnish before the epoxy starts getting eroded. Seems to me varnish is the only thing that resists the sun (and that not 100%) The surface is the only thing eroding and when it goes, its gone. WHATEVER is underneath THEN starts eroding. I have heard this arguement applied to using polyurethane (instead of epoxy) but in the end, it is whatever is exposed to the sun that deteriorates not what is underneath. I raise this question not to disagree, but to get help understanding how a subsurface somehow lasts longer than if it had been varnish, since nothing happens to it until the sun finally reaches it. I hope my question is clear.

1. 
   EdHarrow | Dec 30, 2003 05:58pm | #8

   Not an expert, and the question wasn't directed to me, but that never stopped me before, LOL.  The best way to understand a problem is to toss out one's ignorant opinion to a panel of experts ;-).

   Coatings on wood fail on both surfaces (the side of the coating towards the "sun" and the side of the surface towards the wood.  As we know, wood tends to move about some based upon moisture content and temperature.  This impacts the wood/coating interface, and is, if I understand the problem correctly, independent of the UV capabilities of the material, but it is exaccerbated by exposure to the sun, which tends to, by heating the wood, cause it to move, and for the moisture contained within to migrate towards the surface.  When the moisture reaches the surface it tends to then separate the coating from the wood.

   Those who want the exterior paint on their house to hang on for extra time will prime the backside of the wood.  This helps to minimize the migration of moisture being driven out of the house from moving through the wood, and thus promote the failure of the paint film.

2. 
   JBD | Dec 30, 2003 06:37pm | #9

   Thats very understandable Sailalex.  I does appear to be a contradiction.  As a former 100% solids UV Chemist, and mostly because I've read the studies I referred to, I think I can clear it up.

   OK, first you must understand epoxy.  In all polymer chemistry, any polymer with the  highest molecular crosslink density (hardness) is usually also the most non-permeable, or the most WATERPROOF (epoxies, 2part polyesters, 2part urethanes).  Unfortunately this polymer is also brittle and when cracked, the leaks occur (though good epoxies like WEST has some elasticity).  Epoxy is also 100% solids, which means that the volume poured on is virtually the volume when "dry".  Very good pore filling ability.  Therefore, in the SEALING stage, epoxy is superior to any polymer.  Many even use it in interior furniture due to its filling/nonshrinking ability.

   Another great property of epoxy is that it is one of the most fully reacted polymers out there, therefore less shrinkage over time if protected*.  All other polymers (varnish) will continue to shrink for months/years due to off-gassing of unreacted monomers/non-linked molecular chains.

   Now epoxy's weakness is UV light, which "disconnects" the molecular chains, causing blushing, and lessened waterproofing.  This is from oxidation / free radical degradation.  Here's where Varnish comes in.

   Exterior varnishes not only are less vulnerable to sunlight due to the aliphatic urethanes, but they have additives to negate the UV.   Good marine varnishes have two kinds - Tetratrazioles - actual "blockers" of UV light, and Hindered Amine Light Stabilizers (HALS) that "soak up" the free-radicals that breakdown the molecular chains.  Very expensive additives - I used to use them in my formulas.  These keep the finish very supple, elastic, and best of all it blocks the harmful sun from penetrating the subcoats (epoxy).

   Even better news is that WEST system's 207 Special Coatings Hardener is formulated with UV blockers and non-blush catalysts to make it an even better epoxy sealer for bightwork.

   In an extreme example, that I visualize - its like laying down window glass on wood (epoxy) for solvent/water resistance, then laying down a rubber protective coat (marine urethane)

   Varnish alone won't be a good finish because varnish cannot "lock the grain" the way epoxy does.  It is also not 100% waterproof, so in hot/cold cycling and wet/dry cycling, the wood pores/checks open and shut, tearing the varnish film.  Once a minute fissure opens a little, then moistures gets in and works under the film.  That won't happen with epoxy (as quickly).  Ever see old varnish peeling?  Thats due to the post-cure shrinkage I was talking about. 

   Sailor magazine has run longevity tests and so far the best is varnish over epoxy.

   I personally love the epoxy subcoats for speedy filling of the grain, so that my varnish topcoat will flow out like glass in one, heavy coat.

   Click the link below to see my mahogony decked boat, that took two sealer coats of epoxy, and ONE heavy coat of Marine urethane varnish. 

   "The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)

   http://www.pbase.com/dr_dichro

1. 
   sailalex | Dec 31, 2003 04:09pm | #11

   Thanks, DrDichroic; golly, a UV chemeist, I feel I should pay for this explaination (but I won't).  :) If I get your drift, it is the combo of epoxy and varnish that gets the good results. We are working on a 21' Handy Billy power boat now and encapsulating all the frames with epoxy; we were planning to use polyurethane on the planks but from your explaination, maybe we should use epoxy, although it is very difficult to sand that stuff. Thanks for your explaination; makes sense now.

2. 
   JBD | Dec 31, 2003 07:25pm | #12

   Thanks for the comments.  I hope you're not referring to hull planks.  If your Handy Billy is a traditional carvel plank on frame, then don't epoxy it - you need to allow moisture in to create the seal from swelling.  If the hull is cold-molded or ply, then epoxy/glass the hell out of it. 

   If you were referring to above waterline brightwork, then your good.  I learned most of the plank - on - frame debate from the woodenboat forum, have you checked there? 

   Happy boating - JB 

   "The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)

   http://www.pbase.com/dr_dichro

3. 
   sailalex | Jan 01, 2004 04:38pm | #13

   Actually, it is carvel planking using seam batten construction. You may remember a year or so ago the article in Wooden Boat mag concerning Harry Bryan's redesign and we are doing that one. Yes, I am aware of the Wooden Boat forum.

    Since this boat will not be in the water all the time, I question how much moisture/swelling will take place. The hull planks will be painted white but we were considering epoxying them as we screw/glue them in place. Maybe we should reconsider?

2. 
   EdHarrow | Dec 29, 2003 10:00pm | #3

   Reed - Man-o-War has been around forever.  It was the only thing Dad used, that Great Uncle Dick used, and that "Poppie" used. 

   The first coat was always thinned, maybe 10% with turp or mineral spirits, when applied over bare wood.  If you take the suggestion to seal the wood first (a good suggestion IMHO), then I wouldn't thin the first coat.  I do use Penetrol however - it promotes leveling and helps to keep the edge wet.  Some folks swear by CPES, made by Smith and Company out of the Bay area for a sealant, others use epoxy as already suggested.  What you do by using either is to reduce/eliminate moisture coming out under the varnish, which causes adhesion problems, obviously. 

   Note - there may well be other varnishes available that provide more UV inhibitors.  In any case, more coats are better - four is probably a good starting point.  I often use green scotch-brite between coats so as to avoid sanding off too much of the previous coat - you just want to "scratch" the surface to promote adhesion. 

   JB - a work of art... What are you building?

   
   

   ---

   Edited 12/29/2003 2:03:55 PM ET by EdHarrow

1. 
   JBD | Dec 30, 2003 12:25am | #4

   Hey Fellow WB Forumite whassup?

   That photo is the spray stage of the mahogony electric runabout I'm finishing up.  It has seen the water this past fall, and was a blast.  I already saw schools of fish through the glass-bottoms already. 

   My next step is to make the stern deck out of the rest of the ribbon-stripe mahogony veneer I got from Certainly Wood, and add the compound curved coaming.  I have a few months to go yet before its warm enough to re-launch, so it'll be a while yet before I have time.

   See the construction pics - http://www.pbase.com/dr_dichro

    - Thanks for the comment - JB 

   "The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)

   http://www.pbase.com/dr_dichro

3. 
   HowardAcheson | Dec 30, 2003 03:45am | #5

   The product you have is made by McCloskey.  It is not a very good spar varnish and I know of no marine finishers that use it.  At one time McCloskey made some good products but they have removed so much of the thinners and solvents to meet VOC regulations that it does not perform well.

   Now let me ask, why do you want to use a "spar" varnish?  Spar varnishes are formulated to be very soft and flexible to be able to survive the rapid temperature and humidity changes in a marine environment.  They are used on wooden spars and are not intended for use where they will be walked on or otherwise subject to wear.  They are not used on decks, for example.

   What you want is an exterior marine varnish.  This product is designed for exterior use and is quite a bit harder.  It will stand up to much more abrasion.  If you want a true marine product look for Interlux, Woolsey, Pettit or Epifanes.  Go to a marine hardware store or chandlery.

1. 
   Reed | Dec 30, 2003 07:13am | #6

   wow, you guys sure know the answer to everything, well i am building those bean bag toss games, that have grown very very popular (midwest) the last couple of summers, i make them out of plywood and i was referred to use a marine varnish because it will withstand high temperatures and moisture; the gallon cost about 30-35 dollars at menards and just curious if i am using the best stuff, although i am using plywood (which wont last forever), i just want a great protective and nice gloss shine....it has worked in the past but maybe has worn off by now ?; well i hope this helps and thank you very much for everyone's help; you guys sure do fill my brain with a lot of knowlege...... happy new year to all.....later reed

1. 
   DavidCockey | Jan 04, 2004 07:21am | #17

   I've used Epiphanes varnish on the cabin sides of our boat with very good success. The varnish lasts for several years but the boat is also kept under a tarp and not exposed to sunlight.

   $30/gal is cheap for a good marine varnish. My recollection is that Epiphanes runs around $20/qt. And I use the manufactuers recommended thinner. More expensive than generic mineral spirits or turps but many fewer problems.

4. 
   Mackwood | Dec 30, 2003 11:18pm | #10

   "Manowar" is a very common brand here in the Pac. NW.  It's carried by most hrdwr and even most paint stores.  I have used it quite a bit and it's very good.  That being said, I'm sure there are better products available like the one previously mentioned.

   Daly's (again, a NW outfit) makes a great line of marine grade products.  Try http://www.dalyspaint.com if you're interested. I have no vested interest BTW. 

   How good is "good enough" and how much do you want to spend?  How much difference between $30 per gallon and $50.  Any finish exposed to the elements will require maintenance over the years.  How many years do you want your project to last and how much maint. are you willing to give it?  More questions than answers hugh?!  Best of luck!  Enjoy!

   Mack

5. 
   Gretchen | Jan 01, 2004 05:12pm | #14

   I believe it it McCloskey's--certainly a good enough brand.

   Gretchen
1. 
   Reed | Jan 04, 2004 05:29am | #15

   U guys have had some very valid points and boats in the pictures are great, now on these bean bag boxes that are constructed out of 3/4" plywood, i paint logos and pictures on the plywood and stain them with a basic minwax stain (trying to cut costs--cheap), and then cover with a marine spar varnish, now i am going to put epoxy down on the boards to soak up (plug) up the pores in the wood, however will this affect the paint that is on the boards by discoloring them or peeling the paint or will it have any effect.  thanks for you input and info you guys are very very helpful......happy new year everyone   reed

1. 
   EdHarrow | Jan 04, 2004 05:37am | #16

   Reed, if you've not yet painted them, then paint over the epoxy, and varnish over that.  If you've painted already, well then I don't know the answer.