T&T: Two Part Polyurethane

[Alec McLocklin (amclockl)]

If you have an original couple coats of Cetol, can you give a light sand
and apply other varnishes on top, like Epifanes, or do you have to strip
off Cetol completely first?

Alec




-----Original Message-----
From: trawlers-and-trawlering-bounces@lists.samurai.com
[mailto:trawlers-and-trawlering-bounces@lists.samurai.com] On Behalf Of
Rod Mell
Sent: Friday, March 09, 2007 1:05 PM
To: TWL
Subject: Re: T&T: Two Part Polyurethane

Henry,

The whole secret to maintaining any wood finish, be it Cetol,
traditional varnish, 2 part poly, or whatever, is to have lots of base
coats (probably more than you think you need!)  and then put on
additional maintenance coats BEFORE IT NEEDS IT! This does take a good
bit of discipline, because of course if it looks good why should I put
more on? How often you need to do these maintenance coats depends
greatly on the product and the weather in your area. Here in the PNW I
can usually get by with an application of two coats once per year. These
are preceded by a very light sanding with 320. Also if any spots are bad
(dinged or just weather damaged) I will wood them and build them back up
with a bunch of coats before doing the maintenance coats. Then I will
blend the touched up spots in by sanding and put on the 2 full coats.

I am using Epifanes clear, a traditional 1 part varnish. When I was in
Mexico (on a fiberglass Valiant 40 sailboat), with weather probably
similar to yours, I used Interlux Perfection a 2 part poly. It held up
great in the heat there and I followed the regimen outlined above for
maintenance. The only problem I found with the Poly's is at the wood
joints. The varnish I believe is a harder finish, and tends to crack at
these joints which of course required regular redo of those spots.

In Mexico those that used Cetol had do additional coats every 2-3 months
for it to hold up.

In summary, build of lots and lots of original coats and do your
maintenance coats before it looks like it needs to be done That is the
only way in my opinion to not not have to be perpetually stripping. And
the wood will always look great!

Good luck.

Rod
NiSa
Monk 34 (wood)
Bellingham, WA