How do you finish wood?

[asianflava]

I finally decided to end my break from the teardrop and get back to work. I am not a woodworker so I've never had any projects worthy of finishing. I bought a gallon of Minwax Helmsman Spar Urethane to finish the inside of the tear and the galley. I'm not using any stains or dye, strictly the natural wood color.

The general understanding I have is to:
1. sand the wood smooth
2. apply finish
3. sand finish
4. repeat 2 and 3

My questions are:
What grit sandpaper do you use for steps 1 and 3?
What is the purpose of step 3, to scuff the finish for better adhesion or for smoothness?
What determines how many coats to apply?
Do you finish the insides of cabinets/drawers?
Do you sand the final coat then buff? or is it left as is?

Help, I'm too far along to screw this up.

[ralaco]

asianflava:

What grit sandpaper do you use for steps 1 and 3?
Step 1 – 150 and 180
Step 3 - 220

What is the purpose of step 3, to scuff the finish for better adhesion or for smoothness?
Both

What determines how many coats to apply?
Just go with 3 coats and no problem

Do you finish the insides of cabinets/drawers?
Yes

Do you sand the final coat then buff? or is it left as is?
Just left as is, if you are going to sand you will need to finish it with wax (you will get a very smooth finish).

Raul

[madjack]

Rocky, I like to spray my finishes, if at all possible. You can get an automotive type pneumatic sprayer for under 20 bucks at HF, you shold also get an air/water seperator for the compressor. You will haveta thin the urethane to get a good spray patern,
# 1 start with 80 to 120 grit paper depending on how rough surface is to start and work your way up to a 220 grit...about 3 steps
# 2 spray finish...if you have not done this before practice on some scrap first until you get the hang of it
# 3 use the 220 grit paper here, this step is essentially for smoothness
# 4 repeat 2 and 3, here is where you determine number of coats. As you add coats and sand in between you will be able to feel(with your hand)the smoothness and see the look of the finish...the number of coats will be up to you...the more coats the "deeper" the look of the finish
# 5 cabinets and drawers, I find a couple or three coats with some light sanding is sufficient...mainly you are going for a "seal" coat on them
# 6 if you have done the above correctly no "buffing" will be necessary

the above technique has worked well for me in the past. Some of the fine furniture mavens may have other techniques and steps

madjack

p.s. remember that no matter how you finish your wood to practice on some scrap first to get your application technique down before you start on the real thing

[cracker39]

My technique is pretty much what Madjack does. I made lots of crafts finished with stain/varnish that I sold. I didn't like the mess or extra time associated with staining, so I like to use Minwax Polyshades, a stain and varnish mix that puts on the stain and the varnish in one application. For additional applications, if the color was deep enough, I'd use regular Minwax Poly Varnish for addional finishes. If I needed a darker finish, I'd use the Polyshades again for the next application to deepen it. It requires an even coating, or it will be darker where the finish is applied heavier.

Compressor? Yes, I used my compressor with a filtering system on it to catch water, oil, etc. I used a medium grade auto type paint gun that does either pressure or siphon applications. Siphon for thin paints like varnish, and pressure setting to spray latex based finishes, and it did a great job for both...you can spray latex well when you thin it with water (usually 1 pt water to 4 pts latex paint). I believe I did less thinning with the poly varnishs, maybe 10%-15% thinner. You can also buy the polyshades and clear varnish in spray cans, but it may take a quite a few to do an interior.

Using satin varnish finishes, I could usually get by with just two coats. The first coat seals and raises grain somewhat, so that is why the first sanding with 180 or 220 depending on how smooth it was after the first coat. The sanding smoths down the grain in the wood so that the next coat goes on smoother. For a really nice finish, and I'll probably do this on my trailer, the 2nd application and sanding with finer grit and a 3rd application. I've never had to sand after the final coat, and don't see the need for it if the first coats are applied and sanded properly (no dust or bugs getting onto the surface of the final application before it dries). Buffing with a fine rubbing compound might help, but make sure the finish is completely dry before trying that. I think a gloss coat needs more care and work to bring out a really nice finish, but I hardly ever used gloss. Mostly, I used satin and sometimes semi-gloss.

Here is the top of a narrow trestle table I made for my wife's plants by the window. It is finished in just two coats of Light Oak Polyshades satin on spruce that I will use for my cabinetry.

[cracker39]

P. S.

If you've never used Polyshades and want to try it, buy one spray can and try it first. If you'd rather apply and wipe off stain, then you are only out a few bucks and didn't have to clean up a sprayer or brush. BTW, If I used a brush, it was a good bristle brush, not a foam brush. I don'l like the foam ones for applying varnish.

[asianflava]

Thanks guys, I bought a semi-disposable sprayer from HF. I got lucky because it was on sale for $15. It's a regular 1qt cup gun, should work good enough for what I need it for. I did buy a spray can of the stuff for places where I can't get the sprayer.

[cracker39]

I bought one of those a couple of weeks ago to try out. I am hoping it will spray the varnish well enough for a decent finish. If not, I still have my paint guns that will. If it works, it will make spraying the top sealer easier. I don't like spraying down with a gun with the paint cup underneath. I sometimes touch the bottom of the cup to the painted surface if I'm not careful.

[madjack]

...we have a couple of those HF cheapies...they work just fine...as with all such things, practice, practice, practice 'cause YMMV
madjack

[cracker39]

YMMV? Your mileage may vary???

[Steve Frederick]

You will haveta thin the urethane to get a good spray patern,

Got a rough recipe?? I have a gravity gun..HVLP??
Thanx!!

[madjack]

You will haveta thin the urethane to get a good spray patern,

Got a rough recipe?? I have a gravity gun..HVLP??
Thanx!!

Steve, start around 10% or until it thins enough to start looking "watery"(technical term). Regardless of how I am applying urethanes I have always thinned them a little to help them setup a little faster
madjack

Dale...YES

[asianflava]

What do you use to thin it? The can said Mineral Spirits OR Paint Thinner. What's the difference? Is one better than the other?

[madjack]

...I prefer lacquer thinner, I have used mineral spirits and paint thinner, don't really know what the diff is but they all seem to work....
madjack

p.s. I prefer the laquer thinner as the "volatiles" seem to evaporate faster than the others, causing the urethane to setup quicker

[madjack]

...just a note...if you over thin, you haven't actually hurt anything, you just might haveta put an extra coat or two on to make up for it
madjack

[doug hodder]

Just a heads up....don't get just the lacquer thinner in the can at Home Depot....it typically is pretty "hot" If it were me, I'd check with a paint supplier....lacquer thinners come in a variety of temperature ranges...and if you ask for "lacquer thinner" most automotive finish places will ask if you are wanting to spray with it or use it for clean up..use the "hot" stuff for clean up....I'm no expert, but just ask....the big box stores aren't going to have it in different temp ranges though....and recently some of the lacquer paints, clears, have changed their bases to meet the EPA requirements...and they flash off a lot quicker....just my experience Doug