How do I varnish old, greyed and peeling mahogany?

[Bob Macey]

My new 1962 Triton (Hull 239) is now at home in Superior, Wisconsin after her trip overland from Ohio (thanks to Cross Country Boat Transport). She needs some cosmetic work, especially her exterior woodwork and I have no knowledge on how to proceed. What are my options regarding:

The swashboards: The varnish on the inside is perfect. On the outside it has yellowed, but is not peeling. What do I do? Lightly sand the exterior sides and apply varnish? Strip down to bare wood? Strip down to bare wood on both sides?? If I need to strip, what brands of stripper would you suggest?

The Coamings: The varnish is patchy...some areas are like new, others are peeling, others have completely peeled and the wood has greyed. Do I pull the coamings off and apply stripper...then sand all the way to bare wood? Do you sand all the greyed wood off?

Thanks,
New and Confused Triton Owner

[heartofgold]

Bob,

My take on any varnished surface exposed to the weather is to sand down to bare wood and start from scratch. I would certainly discourage any strippers, sanding can do the job more effectively and in less time. The main cause of peeling varnish is moisture beneath the surface. In my case, it is moisture under the surface cooked in the semi-tropical sun; in your case, it is the moisture freezing during that other season. If some of your varnish is peeling, but the spot next to it is not, it soon will be.

The best advice I can offer you, however, is to do a search on the forum for "varnish." There have been a multitude of topics on this exact issue, and much of what you seek may already be there. Honestly, I learned more about varnishing mahogany on this forum than I ever knew before I came here (and I have a part-time woodworking hobby/business on the side). Good luck, and keep us posted.

[Dave, 397]

Ditto on the sand-vs strip advice...too many strippers cause too many problems on wood with poor adhesion and so on. Especially on a relatively open-grained wood like mahogany, it can be hard to flush out and/or neutralize.

Here is an interesting wrinkle I learned the hard way...Mahogany that has been soaked with salt water and stained will often show up dark splotches even after sanding to a uniform color and a nice surface.

The best bet is to prep the wood and do a couple coats of varnish. If you see a blackish-looking splotchiness showing up where the splotches were before, sand it back again and bleach the wood using an oxaclylic acid based 'wood bleach'. Be very sure to flush it all off and out of the wood well and let the wood air dry in the proverbial "Cool, Dry Place" (kept out of direct sunlight) for a good week before sanding down the raised grain and revarnishing. This should either eliminate the splotches or lighten them enough to make palatable.

Why not just bleach it now?

Well, that oxacylic acid is a bit hard on wood, especially a somewhat soft wood like most mahogany coamings are made of. Best to not break down the cellular structure any more than we have to, right?

Just my .02

Dave





PS---

I have said before, and will again, that I ardently dislike varnishing and as far as I am concerned I suck at it. Totally, completely suck at it.
The old guy I had as a finisher in the guitar shop was a true artist, and he made everything look exquisite the first time around...we did a few electric upright basses that were sculpted out of figured western maple, and they were finished in spar varnish. I could never, ever compare to that work he would do. I made a new altar for our home with spanish cedar and walnut a couple years ago...and it took me a whole year of frustration before I got the semi-gloss job I wanted. Of course, I followed the can directions.

There are lots of good ways to do most anything, and everyone has their own set of tricks and techniques that work well for them...

Recently I had to take the varnish issue by the horns as I have been making interior and exterior parts for the Triton (heavy on the mahogany) and had to get mary started on the job of doing it all. I started out with the unthinned method, she made a mess and got aggrevated, I sanded it all off, and then had lots of time in the process to think real hard back at how my granddad did it, which was how he had learnt from his uncle the cabinet/furniture/boat builder. As best I could recall, and tossing in a few bits of my own and a few bits from others on this forum (and boy howdy have we had discussions on varnish!)...this was what I came up with which has been working well for us:

On the lifting varnish thing, Ditto on that. You can make sure it stays a good long time by having a good low equalized moisture content before you varnish. That helps!
Then...

You notice how years ago the same brands of varnish used to tell you to put the first so many coats down thinned, etc?
Doesn't seem to me the varnish has changed, but I think they are glad to sell you a lot more varnish as you will be cutting back a lot farther to flatten between coats. They're probably in cahoots with the folks that make sandpaper and grain filler!

I dislike using grain filler, even on open-grained stuff like mahogany, as the grain filler does not stick to the wood long-term as well as the varnish will. If you do a nice smooth prep joband then start with the thinned coats, and do not use unthinned varnish until there are no grain pits left, you will have amazing looking pieces that will hold that varnish nearly forever, even underwater!

One bit of trivia---gum varnishes (like the varnishes that we are dealing with, as opposed to alcohol/shellac based 'spirit varnishes') stick a lot better to THEMSELVES than they do to the wood! By getting a good thinned set of coats down there, you give plenty of grip for the finish, as well as the fact that all the grain pits make like traction cleats for the fin. Very hard to have a lifting/peeling/chipping problem if you do a nice job this way. You also blow a lot less money on expensive varnish! Mineral Spirits are cheap, no?

That part really gets my goat, you see...like, I really like Z-Spar Captain's Varnish...but if you follow the directions (they say "DO NOT THIN") it can take forever to dry hard enough to cut back or handle, and it takes a lot of cutting back. I even thin the finish coats about 10 percent with that stuff...but it does look nince and it does go a long ways.

Everyone will either laugh, scream, or vomit...but my favorite general purpose varnish is McKloskey's Man-o-War, thinned as needed of course. Nice cheap varnish at 12.00 a quart or 30.00 a gallon, and it is tough stuff, looks good. Not as high-solids as the Z-Spar, but that's really OK by me.

Our schedule of application is something like 2-4 coats thinned 50 percent to fill most of the grain pits almost completely, cut back close to bare wood in between each with the gold kind of 320-grit paper which is more long-lasting, more uniform in result and easier cutting than the regular cheap garnet paper...followed by 2-3 coats thinned 25 percent cut back likewise to completely fill the grain pits and get a uniform coverage...followed by 4 to 5 coats thinned 10 percent and just cut back enough to get rid of any bus or zits that may have shown up. It's important to thoroughly break the gloss between coats for best adhesion...but if you have a baby's butt smooth surface going, you may also choose to use a scotchbrite instead of 320 for this.

On prep, the 5" random-orbit works well with 80 grit to knock off thick old varnish, or 100 grit if the varnish is spotty. After that we have been going to 120 grit, then 180, then 240, 280, 320. I find that past 120 grit a 1/4 sheet sander gives a better result with less tearing out of the soft grain and a commensurately FLATTER smooth surface than same with the random orbit. The 280 and 320 we have been doing by hand, as again we are going for a good flat surface and the orbital motion of the powersanders tears out the soft grain even with the fine paper. Taking the time to do it by hand is not as bad as it sounds, and it saves time in the long run.

A good varnish job takes a bit of time and is a bit of a pain...but it will last an awfully long time with periodic recoating and will be a thing of joy to look at and even to maintain.


Whew. Now it is up to a nickel's worth as everything I can think of about varnish has spilled out of the random mess in my brain.

[Figment]

Yeah, scrape and sand it all down to fresh wood. Don't be bashful with the sandpaper.... I wouldn't be afraid to be even more agressive than the sanding schedule Dave described. Maybe start with 40-grit. If nothing else, you'll eliminate the potential for chemical incompatibility between the PO's varnish and the product you choose to apply.

Do it right the first time, and the ongoing maintenance will be less arduous. Start with a band-aid, and you'll forever be replacing with a fresh band-aid. (In my opinion, this band-aid practice is what has needlessly turned so many boaters sour on brightwork)

[Mikey]

Get yourself Rebbeca Whtman's excellent books : Brightwork and Brightwork Companion. You can find them new and used on Amazon, about 40 bucks for both. They will save you lots of time and aggravation. BUT, like anything worth doing , it takes time and practice-- there's always a learing curve. Stick with it and good luck, theres nothing prettier on a boat than varnished wood . In my opinion. Michael

[Commanderpete]

I don't use chemical strippers anymore either. I had tried a few different brands over the years. All of them required multiple applications and still didn't take everything off. They don't save you any time or effort. I also worried about adhesion problems.

Sanding is the most effective method. But, you do remove some wood, more than you might think. Not much of a problem on the coamings. The swashboards, however, only have a thin face layer. Much of the wood may have been removed already.

I generally use a heat gun and a real sharp scraper. Its quite efficient, once you get the hang of it.

If the swashboards are good on one side I wouldn't strip that side. No need. It won't matter if the finish eventually looks different on one side, since you can't see both sides at one time.

I have a set of "winter swashboards" made out of plywood, so the good ones don't have to sit on the boat all year.

[Tim]

This winter, I will ebark on the new journey of trying to use a heat gun and scraper to remove paint and varnish from my 23' Lyman powerboat. Later posts and web updates will describe the process, but I have not yet tried this method, though the Lyman guys I have spoken with swear by it.

I am usually a "sand it away" person, and find this works as well as anything. Use as coarse a grit as you are comfortable with for bulk removal, but just remember that the deeper you cut into the wood, the more you'll have to sand with lighter grits to remove those scratches. Use something like 40 or 60 to remove the heaviest stuff, then switch to 80 to smooth it more before beginning with 120, 180, and 220.

I have read that most mahoganies do not react particularly well to bleaching, so do your best with sandpaper. A few dark areas will not ruin the appearance, so it's better to leave a few rather than sand too deeply or create divots that are impossible to remove--and which will show up under your new varnish.

Varnish is like a religion. Enter at your own discretion, and only if you are a true believer. Otherwise, try one of the "cheater" products that require less maintenance. Varnish is gorgeous, and everyone loves to look at it...but maintenance is constant, and unforgiving!

Good luck!

[bcooke]

I would like to hear how the varnish comes up with a heat gun. I have done a fair bit of removing bottom paint with a heat gun on wooden boats. I wouldn't say it was any faster in my opinion but it is a lot less messy and noisy. It turns a miserable job into a boring job which is definitely a step in the right direction.

I always assumed that heat guns and polyester resins don't mix too well so I have avoided it around the fiberglass. Other opinions?

-Britton