Definitely epoxy at least the bare spots. A thin layer of epoxy over the whole deck could be a good idea, depending on the age and condition of the surface. The varnish will eventually fail and at that point the only protection is the epoxy, so it needs to be in good shape under the varnish.

Laszlo

The condition of the deck is very good.  If I want to epoxy the entire deck over, is it ok to epoxy over the remaining varnish provided it is well sanded?

Ingrid,

Nope, sorry. Varnish acts as a contaminant to an epoxy bond and the bond will fail. If you're going to apply epoxy, you have to completely remove the varnish and the very top of the old epoxy layer, at least.

Laszlo 

   Laszlo,

How do you know that you have completely removed the varnish and the very top layer of epoxy? 

Thank you,

Brian

Wow. Talk about resurrecting an old thread! 6 years almost to the day.

Anyway, the way I tell is by wiping the surface with a rag damp with denatured alcohol. The rag will stick and slow down on varnish,  but glide smoothly on epoxy.

Hope that helps,

Laszlo

   I always forgot to check dates, trying to be a good forum user and not ask the same refinishing question over and over :)

What type of denatured alcohol is best, isopropanol, methanol, or ethanol?

Thank you for the help

B

Brian,

I use Klean Strip S-L-X because that's what's available in the paint department of my local DIY store. I believe that it's ethanol with methanol added to keep you from drinking it.

Laszlo
 

   So I sanded my boat and there was lots of white dust. I tried to wipe up the dust with a rag damp with denatured alcohol. Instead of coming clean, the wood cleared up and logged good then turned cloudy. What am I doing wrong? 

thanks for helping a newbie out

BV

Brian,

Not a thing. That's exactly what's supposed to happen.

When you sanded, you left the top of the epoxy layer with a matte finish. Then, when you wiped it with alcohol, you left a thin film of liquid on it that filled in the matte finish and made the epoxy turn perfectly transparent. Finally, when the alcohol evaporated, the matte finish became visible again. Not only is that normal, it shows that you've done it right.

The wet look shows you what the boat will look like with either the next coat of epoxy or a coat of varnish on it. When it's dry, the foggy matte finish shows where you've sanded. Shiny spots are where you've missed or where there's a low spot. The goal is to have the entire boat smooth and foggy, then varnish it.

If you have pinholes that are not going away with #220 sandpaper, stop sanding, put on another thin coat of epoxy over the whole boat and sand again. If you have larger shiny spots that aren't going away, they're low spots. Put a thin layer or 2 of epoxy just on the low spots and sand again. The spots should at least get smaller as the epoxy fills them in. Repeat until the whole boat is smooth and foggy.

Again, it sounds as if everything is going exactly right.

Have fun,

Laszlo

   Laszlo,

I appreaciate the help. Thanks for being a great resource for newbies like me

BV