It will gray, to an old wood look, not a nice silver gray like cedar if nothing is done to it. It will also check and it could check quite bad.

Find a scrap and use a clear waterproofing sealer to see how dark it gets and how long it stays dark.

Any suggestions for the specific sealer or would any of the big name players be good?

For a different thought, why don't you just make the posts match the rest of the trim on your house and be consistent? Why make the posts something different and contrast with everything else? Just curious...

Go to permachink.com, search around for what they sell for outdoor wood preservative/sealants. While they're geared towards log homes, they may have what you are looking for. And, no, you don't have to buy in volume!

Virgil there really isn't any other trim on the house - full brick with thin brick mold around windows and doors, gables are clad.

I use Arborcoat by Benjamin Moore, and I'm happy with it. You can get it in a translucent or opaque look, it comes in a lot of stock colors, and it can be tinted.

LDA Inc those are beautiful projects - the mantel is gorgeous! I'll look into that product as well. Right now I'm experimenting with a scrap piece of post and Penofin because my son has some and it might work for us.

Have you looked at Rubio Monocoat Hybrid Wood Protector? I used it on my cedar fence and it is really lovely. Matte but has a lot of depth and protection for the wood. A little pricey though.

Good luck!

I have a number of exterior doors that are Douglas Fir, and the product I have been most impressed with is the line of exterior coatings by Sikkens called "Cetol." They have a wide range of tones available. All my doors are finished in one of the lighter tones that gives a slight honey color to the wood and brings out the natural beauty of the grain. The doors most protected from the weather are still looking good after 15 years. The ones that get hit regularly by rain get re-coated every 4-5 years.

I'm interested in this question as well. We have a doug fir timber frame, and have some exterior doug fir as well. There seem to be as many answers about finishing as people answering. I'm very unsure about what to do, despite a bunch of reading.

Heritage Natural Finishes (formerly Land Ark I think?) is persuasive to me: http://www.heritagenaturalfinishes.com/SearchResults.asp?Cat=17

They have interior and exterior products: http://www.heritagenaturalfinishes.com/default.asp

am-e I'm doing some experimenting now with clear Penofin because I have some available. It has fantastic water resistance - that much is visible to the eye. No way to know about the UV but it's supposed to be excellent. The color deepens to a beautiful gold/orange but I'm probably going to get some samples with a bit of tint as well to see what happens. With a translucent sealer I can't imagine the tint will make a big change but maybe a bit. Otherwise for more color change it will require a semi-transparent stain/sealer. Now is the time for us to do this, before the brick is in proximity (and at risk!) and while the windows are fully covered so I'm scrambling to make a decision and it will be easier if we use a product that is available locally.

Good suggestions so far. I would avoid anything that forms a surface film, sticking with penetrating products, for easier future prep and coats. The darker the stain, the better the UV protection, and potentially longer time needed between coats.

Ive read Penofin is made from Brazilian Rosewood so unless you want to contribute to unsustainable forestry in tropical rainforests, it may be better to choose something else. There also seems to be cases of unwanted darkening with Penofin.

We've had good success with the Sikkens products, transparent and semi-transparent stains only. Vinegar with steel wool is increasingly popular and might be worth trying a sample but could go too dark or inconsistent with future recoats

Thanks for your suggestions, Springtime Builders. I absolutely don't want anything with a surface film and am only considering penetrating products. The rosewood oil is from "sustainably harvested seeds" - per the Penofin website but I share your concern. Petroleum based products are another concern. There are trade-offs, to be sure. I've done the vinegar/steel wool thing on small furniture projects where exterior protection and consistency are not issues but this would isn't a good place for that application.

Yes perhaps the vinegar steel wool thing is better for more rot resistant species. A builder friend of mine is using it almost exclusively for his exterior siding finishes, but I think it's all cypress which is known for exterior durability. Still, doug fir is better than most woods outside, especially if mostly protected with roof.

Interesting about the seeds, I suppose if they are harvesting seeds from trees that are being cut for timber anyways, there is a case for sustainability. Just don't choose tropical hardwoods for flooring!

Hmm...Reading up on Penofin and Sikkens as I get time.....DLM, I would be interested if you could post pics of your clear and tinted Penofin samples. (I would not mind the darkening if it happened, so that part is not a concern for me). My GC just uses Behr stain for his timber frames. I'm not sure I agree with that. Semi-transparent at most, but I think I just want to leave the color alone (other than mostly natural darkening).

SB - No, not using tropical wood flooring for sure! Our posts are under generous overhangs but will certainly be exposed to UV and wind blown rain and snow - no getting away from that. We had original Doug fir sills on our old house (built in 1936) that were rock solid when we sold 2 years ago. They were painted but even so, the wood will last when taken care of which is one of the reasons we opted to use it here. The other reason being there weren't a lot of choices for 8 x 8 posts :-/

am_e here are a couple of quick pics I just grabbed. Our posts arrived pretty rough sawn. Before they were set in place I used a belt sander to smooth them out a bit - they're not baby butt smooth by any stretch but I wanted a little less texture and splinters!

This is a post cut off that I sanded and put clear Penofin on the left. when they're first sanded the wood is very light as you can see but it begins to darken really fast.

Here are the front porch posts in place. They were all sanded and looked like the sample above 5 or 6 weeks ago and they've already darkened.

Getting color samples of the Penofin is proving to be difficult - none of the places here that sell it have the sample color tubes so I called CA. The website says they will ship but when I told them I'm in NC they directed me to a place in IL. Called them (they have no website) and if I email a list of what I want and my phone # they'll call me for a cc# to charge me for the shipping - oy. I'd like to get this done, like soon, ya know! Could be a week + till I even see a sample then test, then decide then order the color I want..... The clear is beginning to look ok to me.

Thanks DLM! Those doug fir posts looks just like mine:) The penofin looks exactly Danish oil does to me, and I think it looks good. (I suppose any clear oil will look roughly similar).

Watco danish oil or the Heritage Natural Finishes are what my timber frame builder said many homeowners choose. My issue is its not clear to me what the differences are between these various products, so I'm not sure how to choose between them. I may just have to order more samples, both penofin and Heritage, since I already have the danish oil. Penofin more easily allows a tint. I have been interested in a little bit of tint, but I did not like the tinted Danish oils. They did not take evenly, and I did not like the colors. I'm not sure if using some sort of prep/wood conditioner would be worth it. I've had no luck finding other timber frame owners who can just tell me what they did, and the internet has surprisingly not helped. (ok, /whining off).

Which penofin product is that? (Verde?)

No, the one I tried was the Ultra Premium Red Label. My son is building a tiny house and got samples of that and their marine finish to test and visually there was no difference at all. He went with the marine finish because it has the highest mildew resistance and at some point he knows he'll be back in the PNW and figures that's a better product for him. I think you're right that any clear penetrating oil will look pretty much the same - probably Canola oil would look the same for a while as well! I just did a test on a stir stick with Ben Mo Arborcoat Translucent Classic Oil Finish and it looks the same as the Penofin. I've used Watco oil in furniture finishing - which danish oil do you have?