Surface prep

[Ed Nye]

OK, I used search and all that. Now, two coats of CPES like the can says. How long does it need to cure? What's next before the varnish? Do you sand one of those coats off? This is pretty thin stuff, sanding seems sort of agressive.
Ed

[Scott Rosen]

Ed,

The idea is to apply the first coat of varnish BEFORE the CPES cures. That way the CPES and the varnish will bond chemically, thereby "gluing" the varnish to the wood. I wouldn't let more than 24 hours pass between applying the CPES and the varnish. I've applied varnish as soon as a couple of hours, so long as the CPES was dry enough to touch.

If the CPES cures for more than a couple of days, simply apply another very thin coat of CPES (no need to sand, as it will stick to itself regardless of the cure) and then varnish.

CPES greatly improves adhesion, especially on difficult woods like teak.

[Art Read]

Ed, what I've been doing is putting the second coat of CPES down as soon as the first is dry to the touch, then the varnish a couple hours later, (or more likely, the next morning...) No sanding at all 'till the varnish has had a few days to "harden up". Most of the varnish is going to "go away" when you sand, but the wood will be really well sealed and the second coat will go on beatifully. If I really have to get aggressive with the sanding, I'll slap another coat of CPES on any obvious "bare" wood before the second of varnish as well. Being this is the "real world" however, this routine is often varied... Some times I wind up waiting a day between coats of CPES or the first coat of varnish goes on a little sooner than I'd like, but it hasn't seemed to make a big difference in the end results. I'm just careful not to start any job I can't go from fresh, sanded wood to the sealer coat of varnish within 48 hours or so.

[Ed Nye]

Thanks Scott and Art, That was exactly the information I was after. That's the same way I did the first coat of bottom paint when putting a barrier coat on plastic boats.
Ed

[ 05-06-2002, 03:06 PM: Message edited by: Ed Nye ]

[Bob Cleek]

Just another two cent's worth on sanding and varnishing. Recently (news to me!) I started using Scotchbrite pads (the burgundy ones... get 'em at the paint store, the "grit" is color coded) for "sanding" between varnish coats. An auto body and fender guy turned me on to the trick. Regular sanding takes off a fair amount of varnish and leaves scratch marks that the next coat won't really fill until you get down to maybe 320 grit. The Scotchbrite pads take the gloss off, which is all you need to key the next coat, and yet are not aggressive in removing varnish. They can also be used on fairly new varnish, right after it gets dry to the touch, without worrying about gouging and gumming. The residue is so fine that dust problems are hugely reduced. I built up six coats and then let it dry well before I took the Speedbloc to it to get it perfectly fair. Then another three coats with the Scotchbrite pad and it looks fantastic. Also, I did a whole twenty foot boom, two cockpit seats and a spinnaker pole with one pad and it's still pretty much like new. Cost $1.89. I'd have used maybe five bucks worth of sandpaper for the same job. Try it, you'll like it. Not only that, but if you want a nice "hand rubbed" finish, the Scotchbrite pad will give you that easily. No need to waste money on lower quality "satin sheen" varnish (with no UV inhibitors).