Outdoor Finishes Update

[Coop]

I’ve watched Marc’s 2021 video on outdoor finishes several times and his 2024 review on Rubio Monocoat Durogrit. I understand his experience and theory or maybe reality on the UV effect on finishes but still don’t care for the color the UV protection products carry with them. I am building this mailbox post/holder from cedar on the viewers side and treated posts frame on the inside. Has anyone used a clear or semi-clear outdoor finish that they liked or didn’t dislike-like? Looks and future maintenance are the concerns. 
 

[fcschoenthal]

I've used Totalboat's Halcyon on some outdoor projects with good results. It's a water based marine varnish, so no yellowing (unless you want that). It'll take several coats, but it sprays really well and dries in a very short time, so multiple coats in a day is no problem. I haven't had to recoat mine, but since it's a varnish, you shouldn't have to do anything more than spray on some more to freshen it up.

[RichardA]

I was going to recomend trying to get in touch with a high end Yacht manufacturer. Ask to speak to their finish department, then speak to their shop steward or their supervisor, and find out what they use.  Yachts are in the weather 24/7 365 and from what I remember there were finishes that stayed clear without yellowing, that only needed a light sanding every 5 years or so and reapplication.  I would try  Yacht companies like  Outer Reef yachts, Marlow yachts, and Bering yachts, there are others but my memory tells me these are classic yacht companies dedicated to owners that would have someone else do the work of finishing, and those guys would want the very best so they don't have to do it every hour or so.    Just a thought!

[wtnhighlander]

As a low initial cost alternative, there are multiple clear products in the wooden deck market. Most will leave little to no film or gloss, and most will require annual, maybe semi-annual re-application. A pump garden sprayer will do for that. I have had success with these keeping the wood surface clear and smooth, but the color still fades under the relentless sun.

[Chestnut]

2 hours ago, wtnhighlander said:

still fades under the relentless sun.

I personally love the silver look that wood gets when it's sunbleached.  I feel like your advice is best.

A product that has pigment and doesn't fom film that may come in a color similar to your wood is Penofin Blue.

 https://www.penofin.com/wood-stains/blue-label-wood-stain

 https://www.penofin.com/homeowner-resources/where-to-buy

[Coop]

@Chestnut, I tried to call the location that you linked and they no longer have a location in Dickinson, TX. I remember having bought from them before. @RichardA, I contacted three marinas in the Seabrook and Galveston areas and they all buy their finishes in 5 gal. and 55 gal containers. I offered to buy a half gallon from each and they just kinda laughed and blew me off. One gave me a source to their supplier and it was $300 per gallon plus shipping. I ended up using some Cabot Australian Timber Oil that I’ve used on a pair of Adirondack chairs a couple of years ago. I don’t particularly care for the orangish color but my wife approved and maybe the postman will notice and give us our mail instead of our neighbors! 

[Chestnut]

13 minutes ago, Coop said:

Cabot Australian Timber Oil

I think this is a good suggestion. I could have sworn it was mentioned on this site as well with very favorable reviews. I thought it was @wtnhighlander. I always forget about that product but for some reason remember Penofin.

[Coop]

These boards are a full 3/4”, kiln dried cedar, not the picket fence stuff. I plan on a 1/8” separation between the horizontal boards for expansion. Agreed? 

[Chestnut]

If that's anything like the KD cedar I get you'll need to account for shrinkage not expansion. Do you have a moisture meter? Most of the Cedar I can get is around 15%-20% MC.

[Coop]

I do. Pin meter shows 10% on the surface. 

[Mark J]

12 hours ago, Coop said:

I ended up using some Cabot Australian Timber Oil

That's the stuff I used on my (cedar) tree house way back when.  In my experience it will look good for one to perhaps two years before it needs to be reapplied. 

Here's a  crazy thought that's probably too late to think about.  If the mail box were actually supported by the treated lumber inside, the cedar part could be designed as removable cladding.  That way the cladding could be taken to the shop and the flat boards easily sanded and re-coated.

[Coop]

@Mark J, good point. Yes, the frame is substantial and self supporting and the horizontal cedar boards will be attached with treated lumber approved screws which will allow for easy removal. The diagonals are to keep it square and from racking until it is placed in the ground.

[Chet]

On 3/27/2025 at 6:39 PM, Coop said:

the postman will notice and give us our mail instead of our neighbors! 

That's interesting, I live about 1800 miles from you and yet it seems we have the same postal worker.

[Enzo Caleb]

If you're looking for a clear or semi-clear finish that won’t alter the natural color of cedar, there are a few options. General Finishes Exterior 450 is a durable, clear water-based finish that provides UV protection without heavily affecting the wood’s color. Sikkens ProLuxe Cetol also offers a good balance of UV protection and clarity, with a slightly amber tint but still maintains cedar's natural look. For minimal color change, Penofin also makes a semi-transparent oil finish that penetrates well without darkening too much. As for maintenance, oil-based finishes tend to require reapplication every year or two, while water-based options might need less frequent touch-ups. Be sure to test a small area first to see how it reacts with your cedar, as results can vary.