Spar Urethane vs. Water Sealer for Raw Cedar?

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Forum topic by wilschroter posted 07-15-2019 12:36 PM 485 views 0 times favorited 9 replies Add to Favorites Watch
View wilschroter's profile


89 posts in 977 days

07-15-2019 12:36 PM

I’m finishing up a set of 12×12” vertical cedar columns to put outside my house and I’m a little stuck on the best way to treat them for maximum protection against the Midwestern elements.

One suggestion was spar urethane but I’m told it turns the product an amber/yellow tone. Mine are already stained a dark red-oak with an oil-based stain so I’m not sure that would show up.

The other options was a “water sealer” but I haven’t tried that.

In either case I’d love to use my HomeRight sprayer to apply. I did that for spraying a ton of poly a couple weeks ago and couldn’t be happier with the results.

Any help here would be much appreciated.

9 replies so far

View Fred Hargis's profile

Fred Hargis

5645 posts in 2946 days

#1 posted 07-15-2019 12:43 PM

If by chance you mean box store spar urethane, I’d use whatever is next on your list. Anything “urethane” isn’t going to do well in the UV rays outside. Should you want to stay with a spar varnish, any of the true spar varnishes (think boat store, names like Epifanes and others) you will be faced with the amber coloring that they have, and they get darker over time.

-- Our village hasn't lost it's idiot, he was elected to congress.

View John Smith's profile

John Smith

1924 posts in 615 days

#2 posted 07-15-2019 01:23 PM

already stained a dark red-oak with an oil-based stain

what kind of red oak stain did you apply? how many coats did you apply?
do the instructions on the product suggest a clear coat over it to maintain the finish?

is the cedar rough sawn with a fuzzy surface ? or smooth sanded.
what is your vision of the final results.
when it comes to a Marine Spar Varnish type of finish, the surface must
be smooth to accept several (8-15) coats. just one or two coats will not work.
varnish is a UV tolerant finish – it must be sanded and re-coated every year or two
to maintain the UV blocking properties.
if the wood is rough sawn with the fuzz , I would recommend a good quality
exterior solid clear stain. the cheaper you go, the more maintenance it will take
to maintain the look you require.
cedar is one of those woods that moves tremendously with the elements.
so you must apply the appropriate finish to move with the wood.
visit a local “paint store” to see what they have with a 25-30 year warranty.

I am beginning to think that you are looking for a product that you can apply
that will last 20 years without maintenance.
I would keep a couple of gallons of the stain you like on hand to maintain your
columns to the look you want to keep. (it is called home maintenance).
you have this same question posted in other threads. soon, you will become bewildered
and overwhelmed with all the responses and options of putting finishes on top of finishes.
IMHO, don’t put anything over it – just keep applying what you have when needed.
[you may be overthinking this just a little].



-- I am a painter. That's what I do. I paint things --

View wilschroter's profile


89 posts in 977 days

#3 posted 07-15-2019 01:26 PM

Thanks John you’re helpful as always. This is rough sawn cedar already stained with a dark oil based stain on the rough side, which is what I’m trying to protect. My main focus right now is just keeping it as weather proof (moisture) as possible since it won’t get a tremendous amount of sun.

View bondogaposis's profile


5492 posts in 2804 days

#4 posted 07-15-2019 01:27 PM

Don’t use spar urethane, it doesn’t hold up. Instead use spar varnish from a marine supplier. If it is rough then use a stain, I’ve had good luck with Australian Timber Oil.

-- Bondo Gaposis

View LesB's profile


2152 posts in 3895 days

#5 posted 07-15-2019 04:56 PM

I agree with John Smith.
You could have used or in the future use a deck stain (most places can do color matching) which will last longer than just a wood stain.
Do not apply a clear top coat or you will regret it when it comes time to refinish the rough surface.

-- Les B, Oregon

View PPK's profile


1470 posts in 1262 days

#6 posted 07-15-2019 07:56 PM

Don’t use a urethane building finish of any sort. That’s my opinion. It’ll flake off of the cedar in time. I’d use a penetrating oil stain instead. It’ll need to be re-applied periodically, but it won’t look like crap like the urethane will when it starts peeling. In other words, i agree with Bondogaposis!

-- Pete

View wilschroter's profile


89 posts in 977 days

#7 posted 07-15-2019 08:03 PM

@PPK I’ve already used a dark oil based stain. What else would I use on top of that?

View John Smith's profile

John Smith

1924 posts in 615 days

#8 posted 07-15-2019 10:22 PM

Wil – exactly what brand of stain did you use and how many coats ?



-- I am a painter. That's what I do. I paint things --

View therealSteveN's profile


3378 posts in 1027 days

#9 posted 07-16-2019 12:58 AM

21 years in an all cedar sided home. The siding was on the smooth side, and the corner boards were on the rough side. I had to finish it twice in 21 years, and it had about 8 years of good left when we sold it. The colors actually didn’t fade, they just started looking dirty, and power washing didn’t remove it.

Behr Solid Color stain. The last time we coated it would now be just over 20 years ago. Now they have Solid color stain, Premium, premiere, and probably more. Back then they had the plain we got, and some premium something or the other. We used the plain stuff, and never saw reason to spend more money.

This was 2 coats, and essentially it was much like painting it, but paint wouldn’t hang on the rough stuff for a year, much less 15. It was distinct color, as in SOLID color. People near us used Olympic, and had to recoat every 3 years. He asked me several times what I used, I guess he liked staining his house.

-- Think safe, be safe

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