Varnishing mahogany tirm

heartofgold · Post by **heartofgold** » Sat Mar 27, 2004 9:05 am

A question for everyone.

I am about to add a fair amount of mahogany to my boat. How many coats of varnish should I apply? More importantly, how many do I apply prior to installation? And lastly, in the case of a mahogany rubrail or similar brightwork, how many coats do I apply to the inside, hidden edge prior to securing?

I look forward to everyones opinions on this one.

Post by **dasein668** » Sat Mar 27, 2004 10:18 am

Interior or exterior?

I generally try to get a couple or 3 coats on hidden surfaces for exterior wood. One or none for interior. Interior wood I generally finish with 3 coats of gloss and one coat of rubbed effect varnish. (I like the satin look for interior). Exterior wood I try for a minimum of 6 coats. 8 to 10 is better.

Hope that helps.

Post by **Tim** » Sat Mar 27, 2004 11:16 am

For a rubrail or other relatively permanent installation, how much varnish you apply to the back side depends on how you are securing it. If the piece will be well-bedded, you might want a coat or two just to seal the wood, but too much may prevent the sealant from working properly. For an epoxied, permanent piece, I would use no varnish on the back side.

For removable stuff, I'd go a few coats on the back side--doesn't have to be fancy. Interior I would go one coat on the back side as a sealer--maybe more, but not necessary.

Mahogany will turn black if any water gets into it. Therefore, many coats of varnish are a requirement for exterior mahogany (and good maintenance thereafter). For that nice super-smooth glossy mirror look, count on 10 coats at the start--4-6 coats to build thickness, then sand flat and smooth, and then another 4-6 coats on top to build up the ultimate thickness and depth of shine. A maintenance coat at least once a year (for northern boats) and probably 2-3 times a year for more southern craft should keep the finish not only looking good, but also prevent any significant deterioration.

At a minimum, though, 5-6 coats on new exterior mahogany is required, I think. Anything less will fail too fast, and won't fill the grain, either. (I hate mahogany filler stains, but if you like the look you can go that route too.)

Do as much varnish as you can off the boat. It's easier and more effective to do all your work this way, so keep as many pieces removable as you can. If building up 10 coats, do all ten on the bench before installation.

heartofgold · Post by **heartofgold** » Sun Mar 28, 2004 12:00 am

That was exactly what I was looking for. Thank you very much. I have a unique situation with my rubrail, though. I have to really bend the mahogany strips to fit, and then I am epoxying a second piece to the first to fit flush with the hull. Because of this, I believe I will apply my first 3 coats of varnish in the workshop and then permanently secure the rubail to the hull-deck joint. I am currenly using stainless screws, but will also intend to use 5200 for the final connection. I will apply all additional coats (ten is the goal) once all trim is on the boat. I will actually have 4 different mahogany trim projects which will be "tied" together via the rubrail, so hopefully adding the final coats while on the boat will make them appear as a "seamless" project.

My whole reason for adding this rubrail is that at the end of the fall when I finally parked the boat for the winter, the first thing I did was pull off the aluminum rubrail. What I found concerned me greatly. The edge deck, which overlapped the hull, was in sad shape. I ended up grinding off much of the end deck piece at the joint--it was that bad. I filled the joint with 5200 (applied very neatly) and finally finished the exterior to the hull with 2 strips of fiberglass tape and epoxy. I plugged all the original holes (interior) with epoxy filler. So to make a long story short, I am hiding a less than perfect looking hull-deck joint. I believe, though, that with 5200 filling the inside of the seam, 2 layers of glass on the outside, and screws every 6" that I have a very secure joint.

Thanks again for the input. Please feel free to add anything else about this project you think might apply.

heartofgold · Post by **heartofgold** » Sun Mar 28, 2004 12:01 am

That was exactly what I was looking for. Thank you very much. I have a unique situation with my rubrail, though. I have to really bend the mahogany strips to fit, and then I am epoxying a second piece to the first to fit flush with the hull. Because of this, I believe I will apply my first 3 coats of varnish in the workshop and then permanently secure the rubail to the hull-deck joint. I am currenly using stainless screws, but will also intend to use 5200 for the final connection. I will apply all additional coats (ten is the goal) once all trim is on the boat. I will actually have 4 different mahogany trim projects which will be "tied" together via the rubrail, so hopefully adding the final coats while on the boat will make them appear as a "seamless" project.

My whole reason for adding this rubrail is that at the end of the fall when I finally parked the boat for the winter, the first thing I did was pull off the aluminum rubrail. What I found concerned me greatly. The edge deck, which overlapped the hull, was in sad shape. I ended up grinding off much of the end deck piece at the joint--it was that bad. I filled the joint with 5200 (applied very neatly) and finally finished the exterior to the hull with 2 strips of fiberglass tape and epoxy. I plugged all the original holes (interior) with epoxy filler. So to make a long story short, I am hiding a less than perfect looking hull-deck joint. I believe, though, that with 5200 filling the inside of the seam, 2 layers of glass on the outside, and screws every 6" that I have a very secure joint.

Thanks again for the input. Please feel free to add anything else about this project you think might apply.

Post by **Tim** » Sun Mar 28, 2004 8:34 am

heartofgold wrote:I have to really bend the mahogany strips to fit, and then I am epoxying a second piece to the first to fit flush with the hull. Because of this, I believe I will apply my first 3 coats of varnish in the workshop and then permanently secure the rubail to the hull-deck joint. I am currenly using stainless screws, but will also intend to use 5200 for the final connection. I will apply all additional coats (ten is the goal) once all trim is on the boat. I will actually have 4 different mahogany trim projects which will be "tied" together via the rubrail, so hopefully adding the final coats while on the boat will make them appear as a "seamless" project.

That's exactly (for all intents and purposes) what I did when I added my rubrail last December. Good plan--flowing the varnish over the joints between the installed pieces definitely unifies the whole look.

Glissando's New Rubrail