Unfinished Birch Cabinets- sanding prior to clear coating?

[heresyForthe1sttime]

Prior to applying a coat or 2 of clear coat - what grade of sandpaper should I use to clean up the unfinished birch cabinets?    Or is there another way of finishing these you would recommend?  thanks. 

[jason str]

 

 

Pictures of the product will help and if you are refinishing a old cabinet or new.

 

Plywood ? Veneer ?

 

Plywood can normally handle much more sanding than veneer.

[tigerwoodKhorns]

4 hours ago, heresyForthe1sttime said:

Prior to applying a coat or 2 of clear coat - what grade of sandpaper should I use to clean up the unfinished birch cabinets?    Or is there another way of finishing these you would recommend?  thanks. 

 

What does the can of clear coat say?

 

FYI, I just finished some wood on a small project using an old can of Deft that I had. 

 

I think I used 220.  Then cleaned the dust with a rag and then with another rag mineral spirits.  Brushed on, light sanding with an ultra-fine pad from Home Depot, then two more coats.  The finish looks sprayed.  Very happy with the results.  I have a few speakers to do, hope they turn out as well.  Water cleanup as well.  I think Varathane makes a similar product as the Deft seems hard to get anymore. 

[OO1]

4 hours ago, heresyForthe1sttime said:

Prior to applying a coat or 2 of clear coat - what grade of sandpaper should I use to clean up the unfinished birch cabinets? 

do not use sand paper right away ,   start with mineral spirits and 0000  steel wool pad /super fine grade  wool to  clean up the birch , then let the wood dry completely , and if there is any residue ,  use 400 grit sandpaper .

[captainbeefheart]

Furniture grade plywood typically has two face veneer layers of around 1.2mm thickness each. Sandpaper grit will depend on how bad the outside face veneer is. If it's in decent shape you shouldn't need to sand much so use 400 grit sandpaper and then a last light sand of 800 grit to really smooth it.

 

When you say clear coat are you talking about poly or epoxy? I did my unfinished birch La Scala's and after sanding used a Tung Oil to finish it off. I am not sure what exactly Klipsch used for their finished birch speakers but I believe it is an oil/varnish finish and not polyurethane or epoxy.

[carnc1]

Face veneers on most cabinet plywoods are extremely thin these days (as in <1/64" (looks like the new heritage veneers are even thinner), so you have to be real careful with them while sanding or cutting.   A random-orbit pad sander (not disc-sander (too aggressive)) is ok to use (be very careful, or hand-sand near edges and corners).  

My standard way of finishing birch plywood  with oil-based polyurethane (durable):

sand with 220 if needed (plywoods are "sanded" to begin with), 320, 400 (optional) (I generally don't use steel-wool on unfinished wood, it easily snags in the grain, depending on the wood)

apply a coat of minwax pre-stain "wood conditioner" (this is optional but tends to eliminate blotchiness), wipe off (this replaces the wiping the dust off with mineral spirits step)

something as large as a speaker, I have an inexpensive gravity-fed spray gun (medium size cup on the top), and I take things outside, fill the cup with polyurethane and spray 2-3 light coats, sanding with wet/dry 320 grit and mineral spirits between coats. On a warm day, or room, these polyurethanes will dry in a couple hours enough for re-coating. The sraygun is easy to clean, pour in some mineral spirits, spray.  The oil-based poly is not too obnoxious, like lacquers (having acetone, toluene etc), but wear a respirator. 

 

Oil finish (tung oils, Minwax "antique oil" etc), is easier to apply, but not as durable, also easy to repair.  The main issue is with tops, where water or alcohol will easily stain oil finishes.  

Sand as above

wipe off with mineral spirits dampened rag

apply 2-3 coats by brushing and wiping off.

Apply two coats of paste wood wax, buff.

 

Agan, have to be very careful with the thin veneers used. 

[captainbeefheart]

14 minutes ago, carnc1 said:

Face veneers on most cabinet plywoods are extremely thin these days (as in <1/64" (looks like the new heritage veneers are even thinner), so you have to be real careful with them while sanding or cutting. 

 

That's less than .4mm wow!!!  

 

When shopping for veneer I have never seen anything thinner than .6mm being sold, typically .6mm-1.5mm are common thicknesses I see. I guess they do have a cost curve to beat every year for the shareholders to see increased profit margins.