Counsel About Varnish

I posted this over on GuillemotKayaks - doing the same here to cast a wider goes:

I'm about to sand the 'final' coat of varnish off an S&G Petrel for the fourth time due to a dissatisfying finish. I'm giving it one more try, and will then call it and take this vessel for a paddle, no matter the results. I'm sharing issues encountered and application methods used, with hope that folks on this forum have suggestions I can use towards better results.

On the first four (base) coats of varnish, I masked off the hull, varnished the deck, let this cure, then did the same on the hull. This worked well using 2" foam brushes as an applicator, inasmuch as the coats were smooth and even. However, a raised seam at the meeting place of hull and deck coats required sanding, so I switched things up to apply the final coat.

I hung the boat for my "first" final coat, the notion being that I'd work 6-12" sections around the boat and do the whole thing at once. Using 2" foam brushes again, I found that by the time I got around the boat, the previous section had set up to the point of creating permanent brush marks. In other words, I wasn't able to move fast enough. This was particularly true around the cockpit - where the beam is greatest (i.e. the most surface area to cover), and where there are many details to address while applying varnish.

I tried a 3/16" x 4" mohair roller as the applicator on my "second" final coat. The roller covers surface area faster, but despite vigorously rolling it over tape before starting, too many fibers we deposited into the varnish. I was again left with permanent brush marks around the cockpit, too.

For my third and fourth final coats, I tried a 4" foam roller, smoothing off with a badger hair brush. I switched up the process additionally by first doing the deck and immediately afterwards doing the hull, rather than working in full vertical sections.

Foam rollers leave bubbles in the varnish (more so than other applicators I've used) and hold too much varnish, creating perfect conditions for runs. On the last coat I was extra mindful about lightly applying the roller (i.e. to avoid squeezing out excess varnish) but still, runs. 

In addition to previous issues, just enough varnish pushes over the shear seam in places to create a noticeable extra build up. This has happened even though I have been careful about applying and spreading varnish evenly. Hence, varnishing the entire boat in one go may not be the ticket.

One final note about working conditions -- my "shop" is in an unheated basement. I have the shop area insulated in a manner, and get temps to ~65 degrees with a single, radiant space heater. The application specs on the product I'm using (Interlux Schooner 96) indicate nothing contrary for this as a working temp.
So here I am, contemplating a TENTH coat of varnish (but really, the fifth-ish), unsure of how to improve the outcome...

I've considered masking again, but only the deck. In this revised scenario I'd mask off and varnish the deck, sand smooth the seam at the mask line, and varnish the hull, varnishing right over the smooth seam. I'd use foam brushes as applicators, since these have provided the best results to date. 

This approach seems to leave a lot to chance, with no real mitigation against aforementioned issues, and I'm not convinced I'd get a smooth deck-to-hull transition.

Any additional ideas from the crew on this forum is greatly appreciated. Mainly, feedback focused on how to get a good, final coat over the entire boat surface is what I'm after. That said, open questions that I have:

- Would thinning the varnish help (1) with the speed of application and (2) mitigation against runs?
- Would getting the shop warmer do anything other than decrease the cure time? 

Thanks in advance...

2 replies:

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RE: Counsel About Varnish

i have had very happy results just using the technique recommended on the CLC site:

a couple other notes:

for a stitch and glue kayak, you have relatively sharp chines.  so when i varnish, i usually pick the sheer line to seperate varnishing the top from the bottom.  i don't use any masking tape because the varnish joint is very easily hidden in the sheer line.  usually what i will do is take a nice swipe with my foam brush on the sheer line to ensure i don't have any 'bump' or varnish line.

when i come then from the other side, i just follow the same technique using the chine as my edge and the 'swipe' on the seam to blend the two side together with no discernable line.

ensuring your varnish is 'fresh' or thin to ensure it is not too thick is important.   i find that if i have had the varnish around for a bit, it thickens and is difficult to work with.

thin coats.....i am stingy on how thick my coats are.    i do lots of thin coats.

temperature is important....i want it warm enough not to sit wet and collect dust, but not so hot that i have no time to work.  i find mid to high 70's my favorite temperature.

dust management is important....i try to make sure my work place is clean before varnishing.  i turn off fans and heaters or anything that blows dust around while i am working and before the varnish sets....which should not really be that long....certainly less than an hour in my optimal varnish conditions.

not sure if there is any silver bullet here.   i can also say that owners tend to see every flaw amplified in a way that most people will never notice.  so your idea of just calling it a day and going paddling is not a bad idea 



RE: Counsel About Varnish

Unless you are selling the boat or it will be put in a museum and never paddled, you are worrying way to much about this.  I assure you that after a couple paddling trips, you won't be able to tell the difference between a fair varnish job and one that is perfect.  Get you boat out on the water, that is what it is made for!


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