Finishing options for rough cut 1x8 doug fir interior siding

ccgibson · December 04, 2023, 04:47:32 PM

Hello!

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,
-chad

doc henderson · December 04, 2023, 06:21:49 PM

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.

stavebuyer · December 04, 2023, 06:37:21 PM

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.

ccgibson · December 04, 2023, 07:16:04 PM

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 · December 04, 2023, 08:12:31 PM

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.

doc henderson · December 04, 2023, 08:24:03 PM

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.

Oth · December 15, 2023, 08:58:43 AM

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.

SwampDonkey · December 16, 2023, 02:08:22 AM

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.

scsmith42 · December 16, 2023, 08:58:20 AM

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.

Oth · December 16, 2023, 10:54:26 AM

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.

ccgibson · May 04, 2024, 09:33:56 PM

Hello and thanks to all who commented on this thread so far. I wanted to provide a bit of an update.

1) The wood was milled and has been drying nicely. Most of the boards are ~18% now so planning on hanging this summer.
2) I'm very close to buying a planer and planing them all based upon your feedback.

That said, I did a few test boards with oil based products and I didn't quite realize how long the curing and off-gasing would take. With the volume of siding I want to put up, and the fact that I'll be doing this "part time" I'm leaning heavily away from any method that would basically render the interior of the shop un-usable. Plus my wife is extra sensitive to that type of vapor, so I was curious if you all could help me decide:

A) I could just plane and hang naked. I suspect I could use a water based finish later.
B) Hang and use a water based product. From what I've read these all require multiple coats, but fast drying so theoretically I could do 2 of the coats in one day and hang the next.

Since I have a large volume I'm anxious about multi-stage logistics.

Much thanks,
-chad

ccgibson · May 04, 2024, 09:37:21 PM

Here are some pics of both the siding and the intended destination

SwampDonkey · May 05, 2024, 04:58:22 AM

My shop has spruce plywood walls and ceiling. I'm going to be using linseed oil, two coats. I got it in 5 gallon pales. No cheaper than any other finish. But locally they only sell it by the litre jug and three times the price for the same volume. It arrived here 2 business days after I ordered it. Maybe that is an option for you since it would not have all those noxious vapours.

scsmith42 · May 06, 2024, 04:50:20 AM

Quote from: ccgibson on May 04, 2024, 09:37:21 PMHere are some pics of both the siding and the intended destination

Good choice re planing.

If I were you, I'd lean more towards a water based finish. I'd probably lay out a bunch of boards in 5' widths on the floor, with a 2' walkway in-between them, and use a roller with an extension handle on it to apply the finish before installing.

You could also spray the finish after installation using a commercial sprayer (such as a Graco type). The finishing would go extremely quickly but you'd have to be careful not to get runs (plus you'd have to mask / tarp everything off before spraying).