Knotty Pine interior finish for temp swings

[pago cruiser]

Have just ordered about 2300 SF of knotty-ish pine (local lumer yard calls it "Cactus Pine"?) for my 36x26 stick garage, and have been trying to find a finish for the hundreds of 1x6x16 boards. Several threads on this site, and I mostly settled upon an amber shellac, followed by a light sanding and then a final of clear shellac. Not too light, not too dark, not 3 coats...

Except.
Read some of the product reviews on Home Depot. Guy asked a question about its use for an exterior patio, and the factory (Zinsser) replay was:
"Thank you for reaching out! Our Zinsser Bulls Eye Shellac is not recommended for exterior applications. Shellac is a natural resin, and cures to a very hard, inflexible surface that will not expand and contract with wood through seasonal temperature changes."

Whoa. Have not seen this limitation previously: "will not expand and contract with wood through seasonal temp changes".
This garage will only be heated or cooled if I am in it working. Other than that, it will be at, or near ambient.

It will be insulated, but after a week of 20F temps, the temp inside will be really close to 20F... And after a week of 105F, closed up, it will be 120F.

So...is shellac still a good fit through almost 100F temp seasonal swings? I did post a query to the Zinsser folks, but who knows if I will ever get a reply...

 

[RivennHewn]

Interesting little read for ya:

Shellac as a sealer? Its all just hype

You’ll hear shellac tossed around a lot as the “best” sealer, mostly in woodworking magazines targeting amateurs. I’ve come across many professional finishers, however, who believe they should be using shellac rather than the finish itself, a sanding sealer, vinyl sealer or a catalyzed sealer...

www.woodshopnews.com

 

[kbs2244]

use a finish ment for floors
there are many to choose from

 

[PugetDude]

Waterbased polyurethane if you want to keep it light.

Oil-based poly will react with the natural pitch in the pine, turning it darker over time.
Think ("old motel")

 

[The Cobbler]

I used the steel wool and vinegar trick for staining my pine, followed with 3 or 4 coats of oil base urethane.no problems or issues. and the stain looks great & it's cheap.

 

[bb29510]

knotty pine is so nice, i love it, but boy is it a fire hazard with all that turppintine in the wood.

 

[strutaeng]

Yeah, shellac has never been an outdoor product.

Except for maybe knot sealing to prevent bleed though, but still topcoated with something else.

This is an outdoor application? Says interior on your title.

 

[pago cruiser]

Wow. Fast responses. Thanks all.
My bad - interior; but those 100F temp swings are real.
I took a shot in the dark and called the Zinsser tech line - the lady agreed with the recommendation that their shellac product could not handle the temps. She recommended their Varathane (apparently Rustoleum owns both Zinsser and Varathane) Spar Urethane for meeting these temp swings. It is an outdoor product, with (2 me) useless UV protection as well; 2 coats recommend for oil and 3 for water based. 8 hours drying for oil and 2 hours for water.

I'm 68 YO, so if I can avoid applying a third coat to 2400 SF, I'm in...
OTOH, with only 2 hours drying time for water based, I could get 3 coats done in a day... if my back agrees...
Then again, as I do not need UV, maybe the 2 coats water based would be sufficient..

While I admire the "steel wool and vinegar" stain, it would seem to be adding another task, trying to get the right color, and then duplicating that as exterior ambient conditions change; reactions differ at 45 F to 85F, an easy swing on a spring day.

So darn many choices, with "gotchas" to avoid for each product.

Will be picking up some quarts to try this weekend on some samples of my "Cactus Pine".

 

[RivennHewn]

My favorite finish is equal parts Spar varnish, Tung oil, and Turpentine.

One of the easiest finishes to apply, and repair.

The turpentine soaks into the wood, carrying the tung and spar, so you get a penetrating and surface build finish.

And, the turpentine smells great!

 

[tarmy]

We have had this about 20 years…snow country. It was built in 55, so it has seen earthquakes and lots of hot and cold. Looks great still.

 

[Augus7us]

I built a wall in my shop to make a few rooms and have a mezzanine. I used amber shellac on all the boards. I think I went with two coats.

It has been that way for two seasons with no climate control and I don't notice any issues. I did stain each board individually before nailing them to the wall. If you were going to do it after with a roller or something, you may have issues with it separating in-between boards.

 

[strutaeng]

Wow. Fast responses. Thanks all.
My bad - interior; but those 100F temp swings are real.
I took a shot in the dark and called the Zinsser tech line - the lady agreed with the recommendation that their shellac product could not handle the temps. She recommended their Varathane (apparently Rustoleum owns both Zinsser and Varathane) Spar Urethane for meeting these temp swings. It is an outdoor product, with (2 me) useless UV protection as well; 2 coats recommend for oil and 3 for water based. 8 hours drying for oil and 2 hours for water.

I'm 68 YO, so if I can avoid applying a third coat to 2400 SF, I'm in...
OTOH, with only 2 hours drying time for water based, I could get 3 coats done in a day... if my back agrees...
Then again, as I do not need UV, maybe the 2 coats water based would be sufficient..

While I admire the "steel wool and vinegar" stain, it would seem to be adding another task, trying to get the right color, and then duplicating that as exterior ambient conditions change; reactions differ at 45 F to 85F, an easy swing on a spring day.

So darn many choices, with "gotchas" to avoid for each product.

Will be picking up some quarts to try this weekend on some samples of my "Cactus Pine".

Good call on the samples.

Are you looking for any protection from the finish? Any scratches, scuffing and smearing?

The spar varnish is good for outside because it's flexible and allows for expansion and contraction. Yeah indoors with no UV light maybe not a big reason to use it. It will be pretty stinky and pricey. You can probably use the regular oil polyurethane instead. Again it will be smelly. They have the newer formulas that you can recoat in like 4 hours (?) instead of 8 hours. 2 coats should be more than plenty.

I've used the waterborne clears (most are technically waterborne acrylics in spite of what the can label says) and they are really nice. Fast dry time is a big plus. Some tend to impart a very slight blue-green hue, so be mindful of that. I like the Baltic birch or maple with these. Think Scandinavian plywood furniture. They slightly raise the grain of the wood on the first coat. A quick scuff sand takes care of that. Maybe only in the tactile ares in your case.

The diy oil concoctions are not a film finish so they don't really provide any protection. But they do add a nice amber color if you are only looking for appearance.

Bear in mind that the wood would natural amber over time too.

I would probably do waterborne personally. Knock it out in a day if the temperature is right.

 

[charbar]

At a previous job where we did custom trailer interiors (think horse trailer with living quarters in the front) we would use polyurethane and cut it with lacquer thinner to spray though a gun. Usually did three coats with a light sanding in between (back and forth a few times with a sanding sponge to knock the high spots down), but two worked well also depending on the finish you were looking for and how handy you were with the spray gun. Depending on weather conditions and how thick or thin you sprayed it you could recoat in an hour sometimes.

The trailers went from sitting in the Canadian cold to the Texas heat and I never seen a single issue with the finish on any of the hundreds of trailers we did.

 

[BruceMc]

The builder of my cabin used log oil on the interior T&G. Worked well and is still nice 23 years later.

 

[Prospecter]

I have T&G Pine walls & ceiling in my shop. I haven't put any finish at all on the boards. These were factory seconds, less expensive than OSB at the time, and I figured it was just a shop. YMMV.

 

[Hank11]

A couple of suggestions:

DEFT Interior Clear Waterborne Acrylic Wood Finish - Professional Quality Paint Products - PPG

www.ppgpaints.com

DEFT Interior Clear Brushing Lacquer - Professional Quality Paint Products - PPG

www.ppgpaints.com

Coat the backs, edges, ends, faces and install.

The lacquer will roll on and give a nicer finish than you might think possible and will be slightly warm amberish (about what you ask for). The waterborne acrylic will be pale, pretty much completely clear.

 

[ItsNemo]

I love spar urethane (helmsman in particular), have had it on my workbench for 6-7 years now, garage is not normally heated, it has seen all types of chemicals dirt and mess, no issues whatsoever.

 

[jack stand]

EWP (shiplap) with no finish @ 15 years.
Used to be bright almost white and has mellowed to this. (for comparison)

 

[TTTTTT]

Have done lots of T&G pine on interior walls including my garage wood shop. Water based poly is what I use on everything. Easy to apply,dries fast, quite tough. Pick your finish, satin,semi or high gloss.

 

[duneslider]

I have T&G pine on the underside of my porch and I stained it and then put a water based floor poly on it and it has been doing fine. We see a little over 100 in the summer and it is currently 12 deg at night. Doesn't get any direct water on it but it is exposed to the elements and sees temp and humidity swings.

 

[Alchase]

For interior I would use General Finishes arm-R-Seal or de-waxed amber shellac for two or three coats with a 220 grit light sanding between coats.
then Top Coat = Seal A Cell clear varnish.
I have had great luck with this combination. It really makes the grain pop.

You can even add Transtint (colors of your choice ) to the first coats to create subtle color changes room to room.

 

[Firebrick43]

I have some white oak tables finished in shellac in the pole barn that isn't heated regularly so swings from 105 degrees to -20 degrees over the last 5 years with no ill effects.

I think you will be much happier just finishing with blond shellac, not amber and clear. First coat normally is spotchy in color and second finishes it out. And shoot for three coats, it goes on so fast, you can do the second coat immediately after the first coat is finished if the amount is of any size. You really do need to wait 24 ish hours before another coat after the second.

Also make sure you put at least one coat on the back side to prevent cupping.

 

[K'ledgeBldr]

“Garage” interior walls-

Why would they need any kind of finish??? Especially if there is a wide temperature swing-

 

[pago cruiser]

Thanks all for the continued responses.
Picked up some water based stain, water based polycrylic, as well as Varathane Spare Urethane, and a rather unique "Minwax Polyshade satin honey ale" combo stain and polyurethane in one coat. Have seen both good and...not so good reviews on each of these; interestingly enough, most of the bad reviews were for re-finishing existing wood, and most of the good reviews were for a virgin application. Wanted to try them this weekend, but has been **** cold and nowhere to work; until the garage gets the roof on next week.

As far as ...why? Guess I blame my old high school wood shop teacher, Mr Wright. "Wood is meant to be finished, and the right product for the application will last longer than you". Guess he was correct, as we are still using the DEFT finished walnut salt and pepper mill shakers I made in his class in 1969.

Back on topic... I talked with my framers yesterday, asking them to give me a price for installing the R30 in the roof and R19 in the walls, with the pine T&G boards. They looked at me like I was crazy when I said I needed to brush on, then sand, then re-brush the finish on every board before installation. "Mucho trabajo, mi amigo". They said that they had installed pine boards in another garage unfinished, then sprayed on a water-based poly product. Then sanded with those poles intended for drywall ceiling sanding, wiped down with damp rags, then sprayed again. 2 days, start to finish for 1200 SF. Monday (or Tuesday, as we are expecting rain, so they may not show up - but the TJI's installed are all wrapped in plastic) I will ask them if the owner will let me see how it turned out.

Any thoughts on this process? Obviously, only the front of the T&G will be coated; actually, probably sealed. But we are in the desert, so high humidity is something we rarely see except for monsoon storms; during which times the garage would be closed up anyhow.

??

 

[Firebrick43]

If you place finish on only one side, moisture enters, and escapes unevenly. I have seen 20" panels built with seasoned wood cup with the edges 1" with a strait edge placed across. The back unfinished side will grow and shrink more than the finished side. The back finish doesn't need to be pretty or sanded, it just needs slopped on before putting it up. An airless sprayer would be my preferred applicator. The front face could absolutely be finished in place.

 

[pago cruiser]

Firebrick43 - well put. That seems a reasonable effort for a good insurance policy.

 

[never enuf time]

It doesn't matter what your framers ( not finishers) did on another job. All being said ,.I know nothing about a finish in a dry climate. Find an older seasoned painter, ask him what he would do in your situation.

 

[PugetDude]

It doesn't matter what your framers ( not finishers) did on another job. All being said ,.I know nothing about a finish in a dry climate. Find an older seasoned painter, ask him what he would do in your situation.

If you place finish on only one side, moisture enters, and escapes unevenly. I have seen 20" panels built with seasoned wood cup with the edges 1" with a strait edge placed across. The back unfinished side will grow and shrink more than the finished side. The back finish doesn't need to be pretty or sanded, it just needs slopped on before putting it up. An airless sprayer would be my preferred applicator. The front face could absolutely be finished in place.

Asked and Answered.

 

[rnixon]

Here is 2500 L FT. 1x6 t&g select eastern white pine. Finish is water base poly, 3 coats on the face, 2 coats on the back . Working alone, nights and weekends, start to finish took 5 weeks

 

[pago cruiser]

Superb work!
Can I ask how you supported the vertical wall boards? Battens on top of the vertical studs?
I was planning on the simplest means; horizontal boards perpendicular to the studs; but I reall like how yours turned out.

 

[Jakemedic]

Water based poly would be my choice. Like others have said, something that is made for floors would be even better. Lots of work anyway you look at it. Makes me wish I could have afforded tongue and groove, but it wasn’t in the cards when I built mine.

 

[rnixon]

I used furring strips and with a little math , was able to buy board lengths that allowed me to do it without any **** joints and almost zero waste

 

[ybnormal]

Wow. Fast responses. Thanks all.
My bad - interior; but those 100F temp swings are real.

yeah, I believed you, I saw your profile says Tucson

Then again, as I do not need UV, maybe the 2 coats water based would be sufficient..

well, you may THINK you don't need UV protection but that depends. are you going to be sitting there in nice weather with the garage door open? even reflected light will cause possible issues (like reflected light from snow causing faceburns in winter)

example- 20 yrs ago the wife and I had a business, selling baby furniture and kids clothes. we had beautiful hard maple furniture from Canada with a clear finish and some fancy dresses for 5 yr olds. some of the furniture (dressers) were near the front window while the dresses were hung up about 7ft off the floor about 10-15 back from the window. furniture had placards on it with prices. after about a year we moved those placards and found that where the sunlight had not hit the top was still like new, the rest of it had acquired a slight tan. the dress hanging up also suffered some damage and turned from white to cream. and our east facing store front had a covered walkway as seen below. the last thing you want is an uneven color-fade in your nice wood.
good luck with it!