Prep for Varnish

[Thomas1985]

When working on previously varnished surfaces that have weathered spots…

Do you strip the entire surface to bare wood, or just sand off the weathered area and leave the decent existing varnish for over coating?

For example… companionway slider has area about 1” x 3” that is weathered. Rest looks good. Should I just sand the bad spot, or do you have to strip the entire slider?

[Thomas1985]

Secondary question… is brightwork stained before varnish, or does it get all richness from the varnish?

[Jammer]

Originally Posted by Thomas1985

When working on previously varnished surfaces that have weathered spots…

Do you strip the entire surface to bare wood, or just sand off the weathered area and leave the decent existing varnish for over coating?

For example… companionway slider has area about 1” x 3” that is weathered. Rest looks good. Should I just sand the bad spot, or do you have to strip the entire slider?

It depends on several factors.


Generally, when varnish known to be compatible over varnish in overall good condition, it is only necessary to sand good areas lightly with somewhat more attention on bad spots. This is far less work then sanding off all the existing varnish and starting over. The first drawback is that any areas sanded down to wood will not match other areas, especially at first, exposure to sunlight over a period of months will reduce the difference. The second drawback is that you have to know that the varnishes are compatible -- which in particular means that you can't apply two pack unless you know for certain that the existing varnish is two pack.


So you might sand it down to wood because you want it to look perfect when you're done with no color blotches.



Or you might sand it down to wood because you want to switch to two pack for reasons of durability.


Or you might sand it down to wood because the existing finish is in poor overall condition.

[Jammer]

Originally Posted by Thomas1985

Secondary question… is brightwork stained before varnish, or does it get all richness from the varnish?

Typically most of the color comes from the wood itself combined with some tint from the varnish. The wood will darken and change color away from green and towards yellow and red with exposure to light.

[Thomas1985]

Sounds like I'll try spot prep first and see if I'm happy with the end result. I'm using 1 part figuring it's easy and I've conceded I'll be applying coats every few months... A price I'm willing to pay for my pretty wood . I'm even adding more wood to my bow as we speak

I'm also not super worked up about perfect. I just want the brightwork to look good and be protected. Color variance and "character" don't bother me so much

[keepondancin]

You can try using wood bleach or oxalic acid, which is pretty much the same thing, to bring the color back on the weathered area. That might save a deep sanding. Then build up the area with varnish. You can use Epifanes Rapid Coat to build up varnish without sanding between coats. Follow the directions.

[OldManMirage]

I worked for a master marine carpenter when I was young. A guy who had been on the cover of Wooden Boat magazine. He taught me how to varnish. He could get the "mirror" look, I never quite got there. It's a lot of work.

I'm not saying you "have" to take it all down, it's just what he would tell you to do - if you want it done right.

He would start with a good set of scrapers, carefully peeling off old varnish. Move on to 60 grit and then down to 100, then 150, and ending with 220. All sanding down by hand with blocks. No mechanical stuff.

1st coat cut 50/50 with paint thinner, 2nd coat 80/20, next FIVE coats full varnish. Always a minimum of 7 coats.

I've never done it like this since I worked for him. It's just too much work and nobody was paying me for it.

Believe it or not on my current boat I am about to paint all my exterior teak using TotalBoat products, primer and topside paint. I want to preserve the teak but I am done with trying to keep varnish nice. Over the years I've also tried all the other normal stuff too - sealers and oils. Nope, they are all just about as much work as varnish.

Sacrilege I know - but I'm painting mine.

[Thomas1985]

Hey, when you own the boat you can paint anything you want any color you want