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Finishing options for rough cut 1x8 doug fir interior siding

Started by ccgibson, December 04, 2023, 04:47:32 PM

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I'm getting ready for the next stage of my project and one aspect of this I've been trying to research and I'd love any wisdom from this forum.

Now I had ~400+ 1x8 (13' long) doug fir boards milled on site that I plan to use for interior vertical siding in a new workshop/garage here in the Pacific Northwest.  When the milling was happening I took lots of notes about suggestions on hanging, finishing, etc.

I plan to just hang the rough cut boards (no planing, routing, or sanding planned) and as for finishing the local mill guy suggested "a mix of Danish Oil and Varathane works well".  I've read that it is fairly common to mix Danish Oil and various forms of Polyurethane, but I'm having troubles understanding if this is the best method for this large volume of interior siding.  Most examples of Danish Oil also involve a "wipe on, wipe off" approach which is more challenging with such large area of interior siding.

I wonder if I can mix the Danish Oil & Poly and then simply roll it on a rough cut vertical siding. 

Any suggestions for the right & efficient way to finish rough cut Doug Fir hung vertically in the interior?

Thanks much,

doc henderson

I have rolled poly on ERC prior to installation.  it goes fast if you have a spot and some sawhorses to stage it on.  I have done the poly and Danish oil and that helps it set up after is soaks in.  you could wipe off excess, but you have to be careful not to leave cotton from the rag on the wood.  It should cure up dry.  there will be some smell if done in the house.  so, I would probably do it preinstallation.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor


I love the look of rough cut but for any inside use{where the wind and rain can't clean it off) it will collect dust, dirt, and cobwebs that are a real challenge to clean. My interior is all planed and sanded shiplap but even with 3 coats of poly it sure attracts plenty of cobwebs and dust in spots.


Quote from: doc henderson on December 04, 2023, 06:21:49 PM
I have done the poly and Danish oil and that helps it set up after is soaks in.
Thanks Doc, did you do poly after Danish oil or did you mix them and apply together?
Thanks for your thoughts on applying pre-installation.  I could do that pretty easily in the space I have and I imagine it would be way easier then doing it after they are hung.

Old Greenhorn

That was my concern. All that fuzz and rough surface on those boards will soak up a lot of finish and hold a lot of dust and cobwebs, etc. Just saying that borrowing a planer to run them all through on one side might save you a tone of work down the road. Also save you a bunch of finish material, whatever you settle in on.
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

doc henderson

ERC was just poly.  a walnut jewelry box made in 1979 for a girlfriend was the combo, and it worked well.  for this volume and especially rough sawn, I agree the finish will still be rough and not bring out the grain but may make it easier to clean.  the idea of the combo is to really bring out the luster, and deep grain and character.  It will be a waste in my opinion unless the wood is planed and sanded.  the poly will make the wood less apt to hold dust ect. but may have to vacuum the walls on occasion. :)   I used minwax spar urethane in satin on the ERC.  It is to go up on the front porch ceiling.


rolled with a roller handle and a 3/8th inch nap roller, brushed the edges.  this is about 42 bucks a gallon at Lowes if IRC.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor


Second or third planing the boards, if they're rough the dust will cling to em. Assuming you've dried these boards...

For penetrating oil there are a lot of good options out there, takes a lot of coats to finish properly and you'll have to re-applicate eventually. Pretty sure they make Daly's in your neck of the woods.
I'd recommend using a 1k waterbased acrylic poly. Sherwin Williams has one now called Gallery, for whatever reason they don't recommend brushing or rolling it but other manufacturers say you can brush/roll theirs... Idk.
If you can spray it, do that- much faster.


You should really plane (and sand) that interior wood, get yourself a spiral head planer. A good excuse for a new tool. ;D Planed wood will also show off the grain much nicer when you apply your finish. Doug fir can be pretty wood. :)
"No amount of belief makes something a fact." James Randi

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2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))


As others have indicated, rough sawn interior siding can be problematic.

Regarding finishing, the "oil / varnish" mix has been around for years and is commonly referred to as the Sam Maloof finish.  As you've indicated, wiping off an oil based finish on rough sawn lumber may be difficult.

I'd also stay away from poly for a finish, as it will typically yellow over time. Poly's claim to fame is that it is abrasion resistant, which is why it is popular for floors. 

There are some water based finishes that shouldn't yellow over time, and other urethane based finishes other than poly that would be a better choice.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.


You're referring to oil based poly urethane. I only correct because many of the foremost water based finished are being marketed as 'poly' right now. The important part is whether they are 'water White' or non-yellowing. Plenty of the waterbased stuff also yellows over time.
All that being said once your workshop is full of stuff I don't think you're going to notice or care if the finish on your walls has yellowed a bit. Just do whatever is the easiest and wear a respirator while applicating.

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