How many coats of spar urethane

[InNae]

I received my olivewood handles from the bay and they were in pretty rough shape. Not smooth and drips in the finish so i sanded them down and now I'm putting spar urethane on them. I'm ussing the spray on from minwax. How many coats do you recommend I put on? When I'm done there will be some pictures.

InNae

 

[chamm]

In general, I don't think the spray urethane topcoats work as well as the brush-on or rub-on types. I've been using an old-school oil based urethane topcoat (Arm-R-Seal, if you're interested) and it works spectacularly. It penetrates the wood very well, and seems to do a great job of protecting from water infiltration. I really like it because it looks less "plasticky" than spray-on topcoats. It brings out the natural beauty of the wood.

It's not all unicorns and rainbows, though. That stuff takes a long time to cure, especially if you lay it on thick. I allow 3-5 days minimum per coat, which takes a long time if you lay on 4 coats. Also, if you put on an additional coat before the under coat dries, that bottom coat can take weeks to dry, or even not dry at all.

My projects are brush hanging racks, so they aren't immersed directly in water, but mine sits next to my sink and gets an awful lot of splashing.

 

[Garth Libre]

I am opposed to using a poly or any finish which protects against water intrusion. The reason? Simple ... never use a finish which will block the passage of water and moisture unless you have all your bases covered. So if you coat the handle that means water that enters the wood through the knot can not get out. (You didn't coat the socket before the knot was glued in did you? If you did then you are properly protecting against water intrusion .. If not you are allowing water to enter through the knot but not allowing water to evaporate naturally). I think a better finish would be a natural oil finish which allows moisture to enter and exit (breathe).

 

[ks6c]

For another approach, I use CA coating (super glue) - find the thin stuff at a Woodcraft store. I grab the knot in my left hand, apply the CA to the handle, and with my right hand, wrap the handle with a paper towel and make believe I'm a lathe. Turn the brush with my left, spread the CA with the towel in my right. 10 coats and I call it good.

Here's an example:

 

[Zumkopf]

I am opposed to using a poly or any finish which protects against water intrusion. The reason? Simple ... never use a finish which will block the passage of water and moisture unless you have all your bases covered. [snip] I think a better finish would be a natural oil finish which allows moisture to enter and exit (breathe).

+1. Try Tung Oil. Use at least three coats, five is better. It sinks in deep and thus helps prevent water penetration from inside as well as from the surface. And it allows you to feel the wood instead of a plastic surface. I use it on shotgun stocks.

 

[InNae]

Well... I'm four coats in and the whole has been sealed since the knot is not in. I'll take a picture of how I'm spraying it. I feel like I'm getting good coats in it. It looks nice so far. I guess if the wood rots then I'll put tbe knot in a different handle.

InNae

 

[Mr Bob]

+1. Try Tung Oil. Use at least three coats, five is better. It sinks in deep and thus helps prevent water penetration from inside as well as from the surface. And it allows you to feel the wood instead of a plastic surface. I use it on shotgun stocks.

Tung oil is a great finish. It is hard and water resistant, but allows gas exchange. But, be aware of what you buy. Pure tung oil is expensive. On most home store or hardware store shelves, they carry products that are called, Tung Oil Finish... if they do have any tung oil in them, it's minimal. They will generally contain more linseed oil, solvents, and plasticizers than tung oil. There is nothing wrong with this, but they are borderline varnishes, not tung oil.

Get pure tung oil. A little bottle goes a long way. With a dense, hard wood like olivewood, you would need to start with a thin solution of tung oil. Mix tung oil with turpentine, 70/30 to as much as 50/50, and do the first two coats with the thin solution. This will make getting the oil deep inside easier. On successive coats, decrease the turp, or just go straight oil.

In my opinion, tung oil is the foundation for the most beautiful finish you can put on a piece of wood, but it's also next to the most time consuming. Why? Because you add a coat and give it 24 hours to dry before adding the next coat. The first two thinned coats you can get by waiting 12 hours, but the undiluted tung needs 24. So if doing four coats, anticipate 3 to 4 days of waiting.

But wait, there's more waiting... once you're done coating, you need to give the wood one month to dry. Yes, you can get by with 2 weeks, but even a small project like a handle will benefit from one month of drying to give proper time for the tung to harden. You'll be able to polish that handle to a warm, natural, soft gloss, then follow it up with wax on the buffing wheel and well... wood nirvana.

The downside is that it will need maintenance every year or two.

For another approach, I use CA coating (super glue) - find the thin stuff at a Woodcraft store. I grab the knot in my left hand, apply the CA to the handle, and with my right hand, wrap the handle with a paper towel and make believe I'm a lathe. Turn the brush with my left, spread the CA with the towel in my right. 10 coats and I call it good.

Here's an example:

Super Glue (cyanoacrylate), will give you a solid, waterproof finish, but as Garth Libre said, be sure to coat the entire handle, outside and the in the knot hole. You don't want to create a situation where moisture in the wood can not escape, or escapes at varying rates; A cracked handle will soon follow.

If you want to take the Super Glue to the next level, you can do a poor man's wood stabilization. Local hardware stores should carry a product called, wood hardener (I use Minwax). This is an acrylic resin in a solvent. Place the handle in a small Tupperware bowl, cover with the wood hardener, close the bowl and let it sit in the liquid for a few days (the denser and larger the wood, the longer you let it sit). Remove the handle and allow it dry for a few more days. You will then need to polish up the handle, but it will weather water for ages.

Being acrylic, the Super Glue or wood hardener will have a slight plastic look, similar to common polyurethane based finishes. However, the look can be warmed up with a light coat of shellac, shellac based varnish, or even with some carnuba wax off a buffing wheel.

You'll notice that a top brush maker known well to B&B uses stabilized wood for his handles. Stabilized wood is the professional version of the wood hardener process described above. This process will guarantee decades of durability for the handle.

 

[Peter_A]

Excellent info., Mr Bob. Thanks for sharing it.

 

[ks6c]

Tung oil is a great finish. It is hard and water resistant, but allows gas exchange. But, be aware of what you buy. Pure tung oil is expensive. On most home store or hardware store shelves, they carry products that are called, Tung Oil Finish... if they do have any tung oil in them, it's minimal. They will generally contain more linseed oil, solvents, and plasticizers than tung oil. There is nothing wrong with this, but they are borderline varnishes, not tung oil.

Get pure tung oil. A little bottle goes a long way. With a dense, hard wood like olivewood, you would need to start with a thin solution of tung oil. Mix tung oil with turpentine, 70/30 to as much as 50/50, and do the first two coats with the thin solution. This will make getting the oil deep inside easier. On successive coats, decrease the turp, or just go straight oil.

In my opinion, tung oil is the foundation for the most beautiful finish you can put on a piece of wood, but it's also next to the most time consuming. Why? Because you add a coat and give it 24 hours to dry before adding the next coat. The first two thinned coats you can get by waiting 12 hours, but the undiluted tung needs 24. So if doing four coats, anticipate 3 to 4 days of waiting.

But wait, there's more waiting... once you're done coating, you need to give the wood one month to dry. Yes, you can get by with 2 weeks, but even a small project like a handle will benefit from one month of drying to give proper time for the tung to harden. You'll be able to polish that handle to a warm, natural, soft gloss, then follow it up with wax on the buffing wheel and well... wood nirvana.

The downside is that it will need maintenance every year or two.



Super Glue (cyanoacrylate), will give you a solid, waterproof finish, but as Garth Libre said, be sure to coat the entire handle, outside and the in the knot hole. You don't want to create a situation where moisture in the wood can not escape, or escapes at varying rates; A cracked handle will soon follow.

If you want to take the Super Glue to the next level, you can do a poor man's wood stabilization. Local hardware stores should carry a product called, wood hardener (I use Minwax). This is an acrylic resin in a solvent. Place the handle in a small Tupperware bowl, cover with the wood hardener, close the bowl and let it sit in the liquid for a few days (the denser and larger the wood, the longer you let it sit). Remove the handle and allow it dry for a few more days. You will then need to polish up the handle, but it will weather water for ages.

Being acrylic, the Super Glue or wood hardener will have a slight plastic look, similar to common polyurethane based finishes. However, the look can be warmed up with a light coat of shellac, shellac based varnish, or even with some carnuba wax off a buffing wheel.

You'll notice that a top brush maker known well to B&B uses stabilized wood for his handles. Stabilized wood is the professional version of the wood hardener process described above. This process will guarantee decades of durability for the handle.

Great tips, Mr. Bob - thanks!

 

[parastang]

I used 4 coats of spar urethane brushed on with very light sanding with 1600 grit paper in between. Smooth, terrific finish.

 

[jKyro]

Looks great!

 

[Peter_A]

Rob, that finish looks very nice. I definitely prefer a matte finish to a shiny one.

 

[Mr Bob]

That soft matte finish looks great!

Urethanes can discolor or soften with oily woods such as olive wood. If you ever decide to redo the handle, clean it thoroughly with acetone right before the first coat, or even better, give it a couple of coats of thin cut shellac before the urethane.

 

[Big Jim]

I used Minwax water based oil modified polyurethane clear gloss. It provides superior durability, ultra fast drying, low odor, and easy water clean up. I applied several coats by brush. It seems like abut a half dozen. I allowed a day between coats.

The results were really nice.