Hand sanding wood until the surface is 100% flat?

[Ed_Flecko]

I have a wood sanding 101 question...if you properly, and progressively use finer and finer sandpaper you shouldn't need to rely on your wood finish to fill in the pores and level the hills and valleys of the wood, do you? In other words, can't you achieve a perfectly flat wood surface with only sandpaper?

I was watching a video on refinishing a gun stock and the instructor starts with 120 grit, then 220, then 320 and finishes with wet sanding 600 grit. He then puts on about 12 coats of a spray on finish (http://www.brownells.com/gunsmith-tools-...h-prod5529.aspx) and wet sands in between many of the coats.

It's been a long time since I've really tried to finish a piece of wood and make it look beautiful, but isn't relying on your finish to, effectively, create a perfectly flat and smooth finish "cheating"? *I* think you should do a better job sanding.

Am I wrong?

Ed

 

[bioburner]

Wood will like to raise some grain when one puts a finish on it so more sanding if going with traditional finishes.

 

[EdwardC]

I'm no expert, but I always thought of wood as something like a sponge. No matter how far down you go, there are always more holes/pores/grain.

Maybe you mean something different by "perfectly flat", but I take it to mean "perfectly smooth", for which I would think that you'd have to use some kind of finish to fill in the wood to achieve.

 

[sleddriver]

Wood will always have pores. It's the nature of the wood. However hills & valleys are entirely different.

You can achieve a flat wood surface with sandpaper but you have to use a rigid sanding block.

His wet sanding (solvent?) allows the sawdust + solvent to fill in the pores. Multiple coats builds the finish to provide protection.

Some wood has lots of pores...even more if it's cut parallel to them. Oak. Brazillian Cherry. Walnut. Some fill the pores, some don't. I go for the former as it provides a superior finish. It also takes far more time.

Here's a write-up I did a few years back when I refinished a loudspeaker I built:
https://bobistheoilguy.com/forums/ubbthr...nee#Post3503645

 

[spasm3]

Wood is not dimensionaly stable. It will expand and contract with temperature. It will absorb some of the solvent and not be "perfectly" flat. Sanding between coats helps.

 

[ironman_gq]

It would really depend on the finish your using. Paint is very insensitive to final smoothness as far as finishes go, penetrating finishes with pigment are much more sensitive. Get the sanding wrong when using stain or dye on certain woods and you can be absolutely sure to end up with an uneven blotchy finish, linseed oil and other non-catalyzed finishes can be either very difficult or very easy if you follow the right steps. You'll see a lot of oil finishes used on gunstocks because they not only look amazing when done right but are very durable (can't chip off) and scratches can be easily repaired. With an oil finish it's common to use a very fine paper to sand in the first or second coat of oil to fill the pores in the wood and make the surface porosity even out. After that they apply progressively smaller amounts of oil until the wood won't take any more and the finish is even. A good linseed oil finish will make the grain of the wood take on a deep almost three dimensional appearance that glows in the light, they can also take days to weeks to apply and fully cure. Hard finishes just can't match that but they can be applied quickly and more easily and get close.

 

[Vern_in_IL]

You want flat wood? Make sure it is dry, and use a hand plane. Not sure which "number" you would need.

 

[Ducked]

Originally Posted By: Vern_in_IL
You want flat wood? Make sure it is dry, and use a hand plane. Not sure which "number" you would need.


Then a cabinet scraper. No good for a gun stock though, since there are no flat surfaces. I guess "flat" here means no raised grain.