Mahogany restoration

[steveroo]

I've posted a few times and really appreciate the collective knowledge base available here. So I need to ask a question(s) regarding restoring exterior solid mahogany rubrails on my 1955,36' Monk. She's got the traditional solid 2X2 Gunwale/deck interface rail which may or may not be removed to deal with a couple small rot areas on the deck, and a spray rail mid boot that runs 1/2 the length. These are in relatively good condition, but very dry and lacking any type of protection I would like to refinish them as close to original as possible using the BEST possible prime coat, and multiple varnish coats and still have them maintain that red mahogany look. I'm not opposed to oiling them but I'm looking for a product that I can leave alone for 3 years or so. Certainly they will need to be sanded. So has anyone had extreme success with an ultra UV resistant varnish or polyurethane finish. I see these old mahogany runabouts that have been restored and the finish on them is outstanding...My old Tub won't be in a garage, so I need something that will stand up to the wonderful weather we have in Oregon. Also to anyone repainting, I have discovered probably THE best paint remover I've ever seen..it's called PeelAway by Dumond (website) I'm using it to remove 53 years of paint on some beautiful brass running lights and maybe 8 coats of paint on my searchlite..one application can remove up to 30 coats ( their words) but I know it'll handle many coats when applied per direction. It's fantastic stuff and very eco friendly. Lastly..is there something I can apply to the head of a fastener that inhibits rusting and bleed thru? Thanx all I value your input.

[robherc]

I don't know exactly how well it'd work in a marine application, but when I'm working on my tabletops, I want to be SURE that my base wood won't be damaged by kids scraping knives/forks across the finish, then spilling kool-aid all over it.
In order to protect against this, I thin my first three (3) coats of spar Urethane (claims extremely good UV stability, we'll see in 5-10 years of porch use ) at about 30%, 50%, then 70% urethane + 70%, 50%, then 30% mineral spirits thinner. Then, prior to the first coat, I prep the surface with a cloth that is WET (not damp, but not saturated) with mineral spirits, and apply the first coat while the surface is still slightly damp.
This lets me get the Urethane soaked DEEPLY into the wood before I start working on the surface coats, which gives me much better peace-of-mind about the table being saturated (and thus water/rot/stain-proof) deeper into the wood.

Notes:
1. The thinned-out Urethane takes longer to set completely (especially since it's deeper in the wood), so don't skimp on drying time (try double-recommended for the first 1-2 coats.
2. Thinned-out Urethane doesn't develop properties that are as favorable as non-thinned, but it's the only way to get it to soak in deeper -- tradeoff.
3. I ignore the first 3 thinned-coats when counting coats towards the final finish-coat. They all soak-in anywise, so I start counting from coat 1/"base-coat" with the first full-strength urethane coat.
4. My Urethane (Minwax Helmsman Spar Urethane) contains about 35-40% solids, if yours has more/less, change proportions appropriately.

[alan white]

Note that no urethane company ever recommends thinned initial coats (or I've never seen it). I used to thin the first coat but l;ately I've been experimenting with full strength (or what thinning I do, is only to help flow characteristics). Yet many pros do thin their first coat or coats. Who can say whether a side by side comparison has been done? I'd like to hear about it.
In any case, in dealing with old mahogany, use a red-colored epoxy filler, pushing it into any cracks, sand, stain, and varnish (I say varnish because I prefer an annual recoat rather than wooding the job every three-five years.
It's not just the recoating time. It's the removal of old urethane, the sanding, staining, masking, and on and on.
Pick your poison. You should use something like paste filler stain, which goes under the name of Chris Craft red mahogany stain or similar (Google it). Don't use any stain available at the hardware store! You will waste your money. They are too thin and won't do the job.
Others might advise on urethane finishes but I think you'll find there's no magic bullet, just different sorts of hard work.

[PAR]

You can alter the properties and qualities of urethanes if you thin them, especially if you use a fairly low molecular weight solvent. Yep, it'll soak in all right, but then you have a deeply penetrated material, that has a poor bond, which will receive over coats, all of which is relying on this poor bond to stay stuck.

To do your rub rail properly, so you can have long periods in between re-coatings, you have to pull it off. Stabilize the rail with at least three coats of unaltered epoxy (including screw holes). Re-bed the rail, preferably with polysulfide (3M-101 is an example), then over coat with your clear finish of choice.

The longest protection will be from solvent based LPU's, but the jury is still out on their real long term ability to stand up against the elements. Second on the list will be the two part polyurethane varnishes, like "Bristol". These are chemically closely related to the LPU's, but usually have higher UV inhibitors and other "modifiers". Third up to bat are the WR-LPU's which are water based versions of the solvent based LPU's, like that offered by System Three. They're not quite as glossy, have slightly less retention and durability, but are still better then traditional finishes. Batting in the clean up position is the single part urethanes. These are about the easiest to apply and offer pretty good protection. Next is traditional varnish, which is harder to apply (well) and doesn't last as long, but does have a glow that is hard to match by the plastized clear coats. Lastly is traditional oil finish. In Portland's climate you might get by with only two coats per year, but it's an easy upkeep material. It doesn't have high gloss and has to be re-applied often, but is an easy way to go. In my environment in Florida, oil finishes need re-coating every other month to stay pretty, which is more then most are willing to do.

Mahogany doesn't have the "red" color, at least most of the good mahogany. They're red, but not like what you see on furniture, which is stained. Natural mahogany is beautiful, resist staining if you can. To get an idea of the color, rub a mineral spirits dampened rag over some raw mahogany, which will reveal what it'll look like finished with a clear coat. Remember, most clear coats (the LPU's are an exception) will impart some amber to the color, making a warmer glow.

Eventually you'll have to make a choice. Above are some options.

[steveroo]

Wow...2 great chunks of information....so here's what I've settled on after many hours of research, and of course your input...I'm going to wet sand the rails using 320 grit wet/dry and Seafin teak oil as a wetting agent, this should encourage a "filigree" of "original wood " filler to any weathering cracks. Once dry I'll tack-rag them and then prime them with a 50% thinned coat of Interthane, followed by 4 to 6 coats of Epifane Urethane... it appears that this should get about 3 years, ( 2 1/2 in OR ) before it needs recoating, I've also heard from several sources that when the "original sheen" gets to be about 50%, it's time to recoat...that sounds pretty good to me , so I think I'll follow thru and keep up a posting on this lil experiment. BTW as anyone who has done a serious search on this subject... there seems to be as many solutions as there are captains....Bless us every one...

[steveroo]

PAR...didn't see your post until now...you have always had solid Info and I will ruminate on your wisdom LOL Thanx

[PAR]

Don't bother with the teak oil/filler idea. Unless you remove a substantial amount of material, down below the original surface of the raw wood, it'll be sealed with whatever was on there and an oil will just screw with adhesion on new coatings.

Don't thin urethane. The only thing you thin is traditional oil or true varnishes. If it says Spar Varnish Urethane or Urethane Spar Varnish, or similar on the can, it's not a traditional varnish, but a urethane and you really should use it straight from the can. If you want better penetration, warm it up to 90 degrees.

You'll make a career out of trying fix your finish with 320 grit. Start with something more aggressive like 150 or 180, then progress up to 220 for the first two coats. Use 320 after that. Of course sand with the grain.

Single part urethanes will offer you a few years of service in your climate. Don't let this coating get away from you. If it's damaged (cracked, peeling, etc.) then it all has to come off and get re-done. For the most part, you should go over your bright work every year and touch up spots as you find them.

[robherc]

Par-

The 1-part "spar" urethanes are really already thinned a good deal (up to 65-70%) when they come from the factory. I know that several people have said not to thin them any more, but will it really affect the bond much to add more thinner to what's already in the mixture?? Now, don't get me wrong, I know it adds substantially to the drying time for proper adhesion, but I don't see where more of an already-included non-reactive ingredient will fould the mix to a very high extent.