How much varnish is enough?

Builder's Forum
1

Using Interlux Schooner varnish on my WD12, applied two coats and then wet sanded with 340 grit W/D sandpaper, then last night added third coat.  Thinking I will do a fourth coat then light sand then a fifth final light coat and call it good - do you think that is overkill?  

Hull has two coats of k-coat primer (Interlux) on it now after a filler epoxy /microballoon fairing and I plan on three light coats of black Interlux paint. 

Then add padeyes, contact cement the seat (happy bottom) and backrest and then ready to spash in a week+/-. 

How many varnish coats have the rest of you applied?   Starting to wonder - "is this a coffee table, or a boat?"  

 

 

2

   My thoughts on varnish:

At some point (about 3 coats) you'll typically have achieved the finished look you are trying to achieve.  (Almost) smooth, (almost) blemish free, and with some visual "depth."  Thus, you could call that done.  Yes, it is just a boat and not a coffee table, but remember, the purpose of the varnish is to protect the wood (and epoxy).  The fact that a good varnish job looks nice is actually just an added benefit.

Here is my big "However!"  At this point in the build your boat is clean, dry, on the sawhorses, and the sandpaper, varnish, brushes, etc. are all out and ready to be used. It will never be easier to add coats of varnish than now.  The real trick to maintaining a bright finish is to keep these first coats of varnish from ever degrading (which, of course is a very long time and not achievable).  The way to protect the base coats of varnish is to add additional top/sacrificial coats of varnish.  The longer you can go before ever having to strip back down to bare wood (or epoxy) the better - and the less overall work is involved.

Salt, ultraviolet rays, abrasion, oxygen/ozone/pollution, micro-flora (mold, mildew, lichen, marine growth, etc.) and temperature fluctuations (expansion/contraction) are things that degrade the varnish.  And yep, these are all just a normal part of the environment in which a boat exists.  All these things either harden/craze/crack varnish or otherwise try to eat into its surface.  

So, some years of personal experience and many varnish pros much more knowledgable and experienced than myself recommend that you add at least 2 coats of "sacrificial" varnish.  These protect your base coats and keeps them plastic.  I also believe regular waxing (but never wax fresh varnish within about the first 30 days of the final coat) helps extend varnish life.  Wax provides additional U/V and oxidation protection for your sacrificial top coats.

Once you put the boat in service, do occasional touch-ups of deep scratches - especially any that might allow water to penetrate the wood.  Then, depending upon the usage, climate and storage conditions your boat experiences, expect to do a light all-over sanding (of these sacrificial coats only) and re-varnish with at least 2 top coats every 1-5 years; this needs to be done BEFORE you start to see obvious degradation of the varnish finish.  I know that this a big range for time-span, but the differences in the environment experienced by a freshwater, garage kept, often-waxed boat in NY finger lakes as compared to a boat left out on the beach in the FL keys is immense.

I have less expereince with varnish over epoxy (I'm newer to this game) than varnish over bare wood, but I can certainly say that the time and effort spent to maintain and periodically replace varnish top coats is MUCH less than you'll experience if you use fewer coats of varnish, then allow them to degrade to the point of needing to do a complete strip/revarnish job.

In summary, maintaining varnish might be like maintaining clothing (or sails?) - a stitch in time saves nine.

3

...or, maybe it just never is enough.  Puts me in mind of Proverbs 30:15b-16

There are three things that are never satisfied,
    four that never say, ‘Enough!’:
 the grave, the barren womb,
    land, which is never satisfied with water,
    and fire, which never says, ‘Enough!’

...and maybe varnish.  <;-)

.....Michael

4

   The whole bueaty of it is that it is your boat. Enough is when you say it is.

5

i typically do between 3 and 5.

just depends on how it is going....sometimes at 3 i am totally happy.

if on the 3rd, i have a goof like a run or a sag, i will sand it out and do another one or two.

that said, never less than three for me

h

 

6

The only thing I can think of to adding to that long anonymous post, is that epoxy underneath actually makes varnish maintenance easier than for varnish on bare wood. The surface is more stable, does not absorb water and it's much easier to clean down varnish to bare epoxy than to bare wood. This is especially true for epoxy and glass, versus just epoxy, over wood.

Laszlo

 

7

   I think there are three answers to this. How many coats are needed to achieve a certain "look", how many coats to protect against UV getting to the epoxy, and how many as protection against wear and tear? I'm interested in the second two. I'll know when the look is right; it's my boat (Skerry.) But for wear and tear and UV protection, what do the experts say?

8

From John C. Harris (about as expert as it gets) via the Shop Tips:

The kayak will require a minimum of three coats for protection of the epoxy. It will start to look really glossy at five coats. More than 7 or 8 coats is probably overkill.

That's good enough for me.

Laszlo

9

   Wow, Adamwood answered every single post on the forum in one night! That's pretty impressive, except that his answer is exactly the same for every post. 
 

George K