While I've built 5 S&G boats, I know very little about how to varnish them; I just blindly did as I was told. That's no longer satisfactory. Lately I've been reading forums, etc, about the subject but I still have a couple unresolved questions. And I think the answers would be of interest to other builders.
First, a two part question: with regard to Pettit Captain and Pettit Flagship, I understand that these are very similar but Flagship has stronger UV protection while Captain is much easier to apply. I've used 4 to 5 coats of Flagship in the past but I'm thinking I might find it easier to use Captain and apply 6 to 7 coats; would I get equivalent UV protection? But then I've recently become aware that System Three is now selling a varnish, and since the boats are System Three epoxy, would it make sense to use their varnish? It looks like that would be a cost savings of 20% or more. I'd like to see enough differing opinions on this to get totally confused, since in my experience I tend to make better decisions when I'm confused by too many facts.
Second, I've always used a final dry brushing when applying coats of resin or varnish to break any bubbles and smooth the coat. But lately I tried using a heat gun (with great delicacy) on epoxy coats, and I've been getting better results ---really smooth finish that needs no sanding (but see below; YMMV). Can I use a heat gun on varnish? Does anyone use a heat gun on varnish?
Uh, about what I consider a really smooth finish ---it may not meet anyone else's standard. I figure that my boat is only going to be viewed up close when it is on the car or after a trip to or from a launch point, so any minor flaws in the finish will disappear under the road dust. I have no intention of using any of my boats as mantle pieces. They are for play, not pieces of art.
I've got a newly finished boat and a recently renovated boat to varnish before sunny days become a concern next Spring. Perhaps I'll have yet another newly done boat by then, too. Much depends on reorganizing outbuildings and moving stuff from garage to shed...
---Will_S
Heat Gun on Epoxy
I don't know the answer to your varnish questions but I like the idea of using a heat gun on epoxy...I will be trying this next spring when I finish my epoxy work on my kayak. You have answered a question I had about getting that nice smooth epoxy finish...thank you.
Robert N Pruden
heat gun
I would not use a heat gun on varnish. Besides the obvious concern of blowing dust into the varnish you could also get the outside drying faster than it should creating a skin and the varnish under the skin would take forever to dry. I have never been disappointed with anything from System 3. Applying more layers does give more UV protection but it will also make the finish more amber which is neither good or bad it just depends on the look you are trying for. To eliminate bubbles in varnish just tip it of very softly with a foam brush. That's my opinion on your questions.
varnishing
Here's Nick's video on varnishing.
https://www.youtube.com/watch?v=XS67zGTGuuQ
I would add. Foam brushes work great. And my favorite varnish - Epifhanes. You just get better with experience. Work fast so the varnish areas gets covered and let the varnish lay smooth as it settles and eventually dries. Try to maintain the viscosity like when you first open the can. As the can gets lower, more air causes the varnish to thicken. You may have to thin it a bit as the can gets old. Good luck.
Foam brush vs varnish brush
The problem I've always had with foam brushes is that they are too soft, and they break down fairly quickly. I use them for touch-ups sometimes.
Using a foam 'brush', I can't get a thin coat of varnish on the project (kayak,canoe,sailboat trim) unless the varnish is very low viscosity.
With a 'proper' varnish brush it's easier for me to get a uniform thin coat. It's a common beginner mistake to 'flow on' a too-thick coat of varnish, and that can cause problems when the surface cures before the inner layer.
When I learned to varnish, all the 'pro' advice I got was to invest in a good brush.
Perhaps that's changed, or the foam brushes I see for sale are different from the ones that Jay, Nick, and Scott are using.
100% foam
100% what Mr. Abercrombie said. I tried using foam brushes years ago. They soak up to much varnish from the can and they fall apart very quickly becoming mushy. The only time I use foam for is to tip off the varnish and epoxy to pop the bubbles
foam brushes
No doubt, there are crummy cheap foam brushes as there are bristle brushes. I think if you buy some at a paint store or good hardware store vs. discount store you might find some decent ones. I bought some in a package at a discount store and they were absolutely terrible. Its worth the search considering cleaning good brushes is a chore. I have some good varnish brushes, but I never use them anymore. Whatever works, works.
Another varnishing video
Here's a good video on varnishing with a roller and brush:
https://www.youtube.com/watch?v=_VdFzj48BOQ
(YouTube has lots of other good boatbuilding videos from Louis Sauzedde as well..., including a good video on using epoxy and Dynel)
High Density Foam Roller
...it's what I use to good effect. Tried the foam brush gig, too, fell apart.
Robert N Pruden