Sanding grits for plywood with a clear finish

[mjchantry]

Hi everybody,

I couldn't find anything about this in the forums, so I'm hoping that I can get some feedback now.

I have a job sanding a kitchen full of cabinets built from birch plywood. I am going to use my ETS150/5 on this. The only grits of paper I could get in town are the Brilliant 320 and 400. I have one each of 120 Rubin, 180 Rubin, and 220 Brilliant. The coarser grits of the Brilliant wouldn't be in until next week sometime.

I guess I just need some general thoughts on this. What kind of results would I get starting with the 320? Is that too high to even bother with? The finish will be a clear poly of some sort. I'm going to find out specifically later this afternoon.

Thanks,
Matt Chantry

 

[eweber]

I just finish a set of kitchen cabinet made of baltic birch and had very successfull result with the following schedule:

120/150/180 rubin
220 Brilliant
Raise the grain with water
sand again at 220.
Spray 4 layer of water base poly.
Polish with 500 platin before the top coat.
Spray topcoat
Polish with 1000 platin.

Hope this help.

Emmanuel

 

[Dave Ronyak]

120 and 150 on veneered plywood?  I would be afraid of cutting through the thin veneer on most of the plywood that is the only kind commonly available where I live. 

Dave R.

 

[eweber]

On the "artic" birch I am getting there are 13 layers. The 2 outer plies are a little thiner than the inner ply.
The outer ply are rough and are between 1/32 and 1/16. I use the RS2 to do the sanding on the plywood.
I havn't gone through the outer ply yet(keeping fingers crossed).

 

[Good77696e]

what is 500 platin or 1000 platin?

 

[Brice Burrell]

what is 500 platin or 1000 platin?

Here's a link to the Festool USA site for Platin.  Also check out this link on the FOG to the
Festool Abrasives Details.  You'll find info on the Festool abrasives (except Granat).

 

[semenza]

I have started with 150 Rubin on thin veneered plywood many times (ETS150/5)  no problem, just don't grind away in one spot. But most plywood seems to be around 150 surface to start with so I  don't think you would have any trouble to just  start with 180gr (pretty sure I have done this too).  220  would be good to sand to and then apply the poly (or raise grain if water base).  I generally sand between coats with 320 or 400 Brilliant2, and no further. So in a pinch it shouldn't be any trouble to get away with  two grits on the plywood 180 and 320 or 400.

Seth

 

[Good77696e]

Would an ETS 125 work Okay for this job? I'm basically doing the same thing, but I don't own a festool sander yet. I'm looking to buy one soon, just trying to figure out which one to get.

 

[semenza]

Would an ETS 125 work Okay for this job? I'm basically doing the same thing, but I don't own a festool sander yet. I'm looking to buy one soon, just trying to figure out which one to get.

Yes, ETS125 would be perfectly good at this job. Though if doing large panels the ETS150 will cover the area much faster.

Seth

 

[Good77696e]

When you "raise the grain" with water... Does that just mean you spray water on it, let it dry, then sand again?

 

[semenza]

When you "raise the grain" with water... Does that just mean you spray water on it, let it dry, then sand again?

Pretty much , although I tend to flood /wipe with a sponge.  Sand again with the same grit  last used, and don't over do it exposing new wood fibers.

Of course that is not really necessary if not using water base finish or stain.

Seth

 

[tiralie]

I have a job sanding a kitchen full of cabinets built from birch plywood.

Matt:
Do those cabinets have a finish on them now?
Tim

 

[Good77696e]

The last finishing project I did was on cabinet grade maple plywood. I didn't sand the plywood. I applied minwax wood conditioner, then stained it, then sprayed several coats of water based polyurethane, sanding between coats with 400 grit. I was very unhappy with the results... If I was right in front of the project looking down it looked fine, but if I was looking at an angle I could see scratch patterns.

Do you have any suggestions to solve this issue? Am I sanding too much? I notice that you said you apply 4 coats before sanding.

 

[tiralie]

If I was right in front of the project looking down it looked fine, but if I was looking at an angle I could see scratch patterns.

Do you have any suggestions to solve this issue? Am I sanding too much?

Sounds like your top coats are sprayed on too thin.

Measure the first coat with a wet thickness mil gauge to make sure you are applying a thick enough coat. After that you will be able to tell weather you are applying the right thickness or not.

How long did you wait between coats?
Did you use a water borne stain?

Tim

 

[Good77696e]

OK, maybe that is the case. How thick should it be?

I waited about a day between coats.

I used an oil based stain.

Thanks for your help Tim.

 

[tiralie]

OK, maybe that is the case. How thick should it be?

I waited about a day between coats.

I used an oil based stain.

Thanks for your help Tim.

I am sure others will chime in but it depends on the solids content of the coating, but for Target EM9000 polyurethane (30% solids) I use a min. of  1-2ml on a wet mil gauge.

What product (kind of polyurethane) did you use?

Tim

 

[Good77696e]

I used Varathane gloss polyurethane.

 

[Good77696e]

Where can you buy the Target EM9000 polyurethane?

 

[JHC]

OK, maybe that is the case. How thick should it be?

I waited about a day between coats.

I used an oil based stain.

Thanks for your help Tim.

Is your paper staying clean? A single buildup that you don't resand with clean paper can cause deep scratches that show in the finish. You may need to wait longer for a wb finish to cure before you sand.

 

[tiralie]

Where can you buy the Target EM9000 polyurethane?

Woodessence
Really good guys.
They are happy to help if you have questions but the Target web site has a great forum.

I waited about a day between coats.

I think you should re-coat sooner.
Under ideal conditions you should be able to apply a new coat after an hour or two and you don't need to sand much but rather take the "nibs" off. 
This way you won't introduce any problems that Tommy is referring to.
After 24 hrs., polyurethane like EM9000 is on it's way to curing and needs to be completely sanded so the next coat binds properly.
I also use a 3M scotch brite pad rather than sandpaper to get rid of nibs etc. and then I wipe any powder residue with a clean cloth.

BTW, how long did you wait after spraying your first coat of polyurethane over the stain?

Tim