Thanks, Lomo. My concern with shellac has been that I just don't know much about it. I know people like to formulate it, making their own custom batches, but that's a trap for a guy like me who get's paralyzed by too many options. Do you know of an off the shelf brand that sprays well?

If the ceiling is up already you will spray. If you want it ‘warmer’ use an oil based polyurethane, if you want a clear finish use a water based poly. Regardless they will get darker with time (pine naturally ages darker as anyone with pine floors and carpets can attest). I would skip staining unless you are skilled and can do it prior to install. Regardless of all of my suggestions make lots of test boards on the actual wood, it’s the only way to find a finish that YOU like. Spar varnish and deck finishes are designed for outdoor use and I would avoid them here- unnecessary and possibly not good for indoor air quality.

I have to agree this would have been best done before install. All would ages and gets darker with time. Waht was the reason for pine if you did not love the natural beuty of it ? Now IMO spray it with a poly finish that does not stink for weeks and be done

It will change color with time, no matter what you do.

Shellac is a wonderful finish for this kind of project, the pre-mix Zinnser stuff sprays beautifully. Google how to read the date codes and be sure to get fresh material. Use clear for lightest, amber for a darker more traditional look, or a blend of the two to get something in between. You'll want both organic and particulate respiratory protection when spraying that much.

Poyurethane can also be used, I'd test different brands to see what outcome you prefer. Many look very plasticy unless you are able to rub out the finish, not practical on a big ceiling. This is a real problem with most of the water-based uretnanes, My personal favorite poly is called Last-n-Last (oil based), as it looks much more like a traditional varnish. Spraying oil based finishes is not much fun in my limited experience. I'd apply it by brush before installation. General FInishes and Target Coatings both sell WB urethanes that look much better than the big brand name stuff.

Whatever you do make test boards using a range of actual wood that's used in the ceiling. Do the entire finishing schedule, including all sanding steps, on your test pieces to have a more accurate idea of what the final result will be.

A water based top coat product that I've had great success with is Target Coatings EM-6000 WB lacquer. Sprays perfectly, dries quickly and looks great. You can add crosslinker to make it quite tough. A seal coat of colored shellac can be used under it if you want to adjust the color. This would probably be my top choice for your application.

I don't want to beat a dead horse... I agree with @HALLETT & Co.

If it were mine, I would leave it. Live with it, as is. enjoy it.

Who installs that much wood overhead without finishing it first??? Someone with scaffolding and a Michaelangelo fixation to do it all laying on their back 20’ in the air?

Shellac is traditional with pine. It gives it a soft warm glow, and accents the grain nicely.

Take comfort in knowing, in most cases, nobody will be walking on the finish and it will receive little wear.

To be clear... The Pine T&G isn't installed yet. I'm not totally crazy :)

Thanks for all the replies

One of the beauties of shellac is that cleanup is easy-- you don't really need to clean brushes or roller covers except maybe for a quick rinse. Just let them harden and then a quick soak in denatured alcohol the next time you want to use them and you're good to go.

I'm not at all sure I'd use a roller in this situation (well, I'm sure I wouldn't); shellac is the easiest finish there is to spray if you're set up to do that, even the cheapest Horrible Freight conversion gun works well with it, or if not, splurge on a Grammercy shellac brush. You won't believe how much difference a brush can make. It will be quick work with the 3" brush and look better than with a roller.

I would suggest a rub-on stain and a rub-on polyurethane. It will be more time consuming but I think you might like the results. The rub-on stain should give you a nice color and the rub-on polyurethance will seal without making the wood look plastic. Good luck!

The main reason for spraying is ease of application of larger amounts. The main reason not to spray is everything else. Cleaning the spray rig. Wearing a respirator for hours. Overspray, if you haven't dialed it in good, or are inexperienced. Lots of "learning opportunities" that will come n useful if you are going to do other finishing work. And shellac is far more forgiving than polyurethane for drips and runs, or areas without enough coverage. A new coat just melts into the old coat. Razor blade the drips, sand, and a light mist, and it looks like it never happened.

I did a 2500 sq ft home with every ceiling in tongue and groove pine. For a finish?

Nothing!

In has slightly darkened, but that is it. People comment today how good they look and they have been up for 30 years.

No expense

No time loss

No funky smell for weeks in the house

To me, doing nothing simetimes makes the most sense. In 30 years I have yet to walk or scrub the ceilings.

The main reason for finishing is that wood is porous. It will absorb dirt and odors if left in the raw state. Ever see a ceiling over where someone has one of those smelly candles burning? Or smell a home that doesn't have a good kitchen vent, and believes cabbage is the way to good health?

A topcoat helps to deter moisture. And wood movement. Best to finish TnG before installing in case it shrinks. Laquer would work great, water borne is good. A roller will work fine just don't over

Just don't overwork it.