Power Sanding Between Finish Coats?

JuliMor

Member
Joined
Jan 24, 2013
Messages
80
I have never used a power sander to scuff up a finish coat in preparation for the next coat.  Reading up on Festool sanders, it seems some can be ultra gentle so they can be used for that application.  Is there a sander, sander accessory, etc. that can safely be used for this application?  Specifically, I'm referring to wood that has been dyed and the first coat of finish sprayed on.  And then between successive coats of finish.

I think I already know the answer to this - Can the RO 90, RO 125 or ETS 125 be accessorized to do this task?  [scared]

Or should I just go see a shrink to remove this mental block I have about this stage of finishing?  [big grin]

Thanks,
Julie

 
ETS 125 would be your safest choice. It's what it was designed to do.

320 paper and finer for between coats. Use the grit the product manufacture recommends.

Tom
 
I have always thought that R.O. sanders are too aggressive for scuff sanding between coats. For years, I used a 1/4 sheet PC Speedbloc sander but the dust started causing respiratory problems. Picked up a RTS 400, great little sander with terrific dust pickup. I did have problems using ML Cambells white Clawloc primer with Crystal topcoat. I was getting "pigtails" using 220X, switched to 320X and the  problem went away. If you go into most finish shops, they are using orbital sanders on the sanding sealer, between the 2nd and 3rd coat I will lightly hand sand and use a maroon Scotch-Brite to knock down any roughness.
 
Julie,
I assume that by first coat of finish you are referring to a first coat of poly, lacquer, or some other top coat. You should try using a sanding sealer after your stain and before your first top coat, It will open up new worlds to you in getting the right finish you are looking for.

Alright, I'm back from the spray booth to finish  [smile] my thought.  Since I learned to use a sanding sealer a few years back, I have not done any power sanding between top coats on my projects, just a few quick scuffs with the 320 sanding sponges and I end up with a great finish.

Mike
 
Like Tom and David say an ETS or RTS with paper or Scotch-Brite pads >320. RO is too aggressive and a bit like an elephant gun in orbital mode.
Tim
 
Another take on this. For small surfaces where hand sanding won't tire you out, use a Vacuum ready Mirka hand Sanding pad with their Abranet abrasive. Turn your vacuum/extractor way down, and use 320 grit or higher abranet to scuff, very lightly, the surface in prep for next coat. I haven't sanded through a coat with either oil based or water based finishes using this method. But, I wouldn't want to do this version for large areas either.. [wink]
 
Julie

My company does alot of shop and field based cabinet grade finishing...in both primer/paint and stain/clear combos.

We have had very good look with the Festool orbitals. We do not use Rotexes much in this application, mostly because of weight, balance, cumbersome in carcasses, and difficulty in one handed use. The orbitals are made for this. The ets 125, rts 400 and dts 400 are all good choices, and all can double as small drywall patch sanders and other uses.

On dye and clear finishes, after spraying first coat, any of the ets/rts/dts are great to float for scuff sanding. With clears, all you are looking to do is dull the sheen, smooth it off and create just enough abrasion for the ensuing coat to enjoy good adhesion. Granat abrasives (320 grit, give or take, depending on situation) in higher grits is ideal because it doesn't load, or therefore scratch, which in turn is a tribute to the superior extraction that the smaller sanders, by design, have. Hand sanding on clears is very difficult. It can be done, and with good results, but its just more efficient to have a system of sander/abrasive/extractor to take some of the risk and time out of it.

As others have noted, and this is critical, with the orbital sanders, because their extraction is so strong, it is important to turn the vac extraction way down to keep the sander from getting rowdy and turbulent on the surface. At low extraction and high speed on the sander, fine finish sanding goes pretty smoothly. Another important consideration is to be sure that your first coat of clear is well cured before sanding. Product comes into play big time in that sense. With lacquers, we can turn it around in about 25 minutes. With other products, it can be 24 hours before it is safe. Once you know these variables, things become simpler.

Please keep us posted. Time to boot that mental block. Good luck.
 
I'm using a Transtint dye formula I created, mixed in water, for the color.  Then General Finishes EnduroVar Satin for the top coats.  All the doors are dyed and one coat of EnduroVar has been applied, with an HVLP sprayer.  I think it's been a couple of weeks (really longer but I don't want to admit it  ::)) so the finish is completely cured.  Even though I pre-raised the grain, the WB dye and finish managed to pull a little more fuzz out of the wood.  On the sapele more than the mahogany.  So even though EnduroVar directions say you can recoat within X hours without sanding, I have to sand out the remaining fuzzies.  FWIW, this doesn't affect the dye color.  The panel is sapele and with hand sanding it's looking like the top and bottom of the panels aren't sanding out as even as the rest of the panel.

I'd probably have to go with the RTS because of the door configuration, and since that is something that would get a lot of use in the long run, it's the best choice for me.  I'm not seeing any soft pads in the catalog so I'm assuming the RTS wouldn't need this?  I'm guessing the foam pad wouldn't work for this application?

Thanks for the help,
Julie 
 
Julie

I find the stock pad to be just right. Any skooshier and I think it'd have attitude.

I love working with sapele. And am also a finish procrastinator. I have a pile of mahogany cabinet parts in the shop waiting for that special moment.

Hope you'll post some pics of the sapele when finished.
 
Scott B. said:
I have a pile of mahogany cabinet parts in the shop waiting for that special moment.
[laughing]

Scott B. said:
Hope you'll post some pics of the sapele when finished.
This is where I am now, dyed with one coat EnduroVar
doors_01_zps75287f89.jpg


My arms are tired so the foreman told me to take a break  [cool]

I was looking at the RTS and compared it to the LS.  Both have the same abrasive selection.  Both have the same pad size.  The LS is 1.5 lbs heavier.  The RTS has 6K-12K OPM while the LS has 4K to 6K SPM.  There's a bunch of profile adapters for the LS.  And the LS is $140 more.  To me the big question is does the LS do everything the RTS does?  Or do the OPM vs. RPM numbers make the RTS a finer sander?

Okay, back to work!
 
The RTS and LS might use the same abrasives, but that's where all comparison ends. They are very different machines. For general sanding work, like what you show in the pics above, I think the RTS is a lot better suited than the LS.
 
Beautiful pictures, Julie. What is the stain tone?

Based on the pictures and the layout, if I were stepping in with you on that, I'd be going DTS all day long. Well, it wouldn't take all day, but you know what I mean.

And I agree with Alex, this is no place for the LS to get involved.
 
Thanks guys!  You've answered my question and saved me a few bucks, that will probably go to sandpaper... [blink]

The dye on the doors is Transtint - 8 parts Brown Mahogany, 7 parts Golden Brown and 6 parts Bright Red. Once you get to three top coats, it looks much richer.  I'll bet we mixed 20 different formulas.  The one I liked the most was a 50/50 with Brown Mahogany and Bright Red.  But it was too red for the rest of the wood in the area.  The kitchen opens to the great room.  The wood in there is red oak with Early American Maple stain. So we took the formula more towards brown than red.

I'm dying the existing oak face frames Ebony.  This is an idea of where we're going with it:
doors-oldnnew_zps2a7d46de.jpg
 
Julie Moriarty said:
Thanks guys!  You've answered my question and saved me a few bucks, that will probably go to sandpaper... [blink]

The dye on the doors is Transtint - 8 parts Brown Mahogany, 7 parts Golden Brown and 6 parts Bright Red. Once you get to three top coats, it looks much richer.  I'll bet we mixed 20 different formulas.  The one I liked the most was a 50/50 with Brown Mahogany and Bright Red.  But it was too red for the rest of the wood in the area.  The kitchen opens to the great room.  The wood in there is red oak with Early American Maple stain. So we took the formula more towards brown than red.

I'm dying the existing oak face frames Ebony.  This is an idea of where we're going with it:
doors-oldnnew_zps2a7d46de.jpg

Nice work Julie I have never dyed mahogany but, I'm interested in your results.  I make furniture and can build with wood from one batch (or one tree) and get good color matches but I can imagine that as wood gets more scarce matching colors with dyes is very important.

Here is two night stands with Honduras mahogany solids and Sapele  ply panels where I did get reasonable color matches.

Jack
 
These are dyed sapele, just less TT red than Julie's mix.

I agree with Scott, DTS is the one you need first, then the ETS.  If you want to try one, let me know.

Tom
 
A little late to the thread but ......................  the LS130 has a straight linear sanding stroke literally one direction back and forth. As already said not the sander  to use between finish coats unless doing a narrow part or trim.

I tend to put finish on fairly thin so if I have stained or dyed something I will  generally do two coats before sanding the finish to avoid going through into the color.

Seth
 
jacko9 said:
Nice work Julie I have never dyed mahogany but, I'm interested in your results.  I make furniture and can build with wood from one batch (or one tree) and get good color matches but I can imagine that as wood gets more scarce matching colors with dyes is very important.

Here is two night stands with Honduras mahogany solids and Sapele  ply panels where I did get reasonable color matches.

Jack

Jack, those nightstands look awesome.  Colors from the camera and through the internet aren't always true but from what I'm seeing here, the drawer front on the left night stand looks a lot like what I got from orange or yellow Transtint on sapele. I got to know TT dyes all to well.  I think I have 8-9 TT colors now.

My experience with mahogany and sapele is mahogany takes in less dye than sapele and darkens naturally less.  We were going to try to make the rails & stiles darker but I was not up for the task.

Tom,

Those doors are impressive.  I'm guessing veneer panels?  Very cool!

Seth,

I really don't yet understand the mechanics of the different Festool sanders, except the ones I now own.  Pre-Festool life was simpler but very dusty!  Maybe I need to see a demo on the DTS vs the LS to understand what they both do.  That being said, right now I'm looking at finishing the doors, making the drawers and putting 1/4" sapele plywood over the cruddy fake wood panel sides of cabinets that are exposed on the sides.  I'm figuring two sheets of 1/4" ply will cover that nicely but that will have to be sanded, dyed and finished... and probably sanded again before the final coats go on.  Maybe a 12"x12" pad sander is in order.  [laughing]

I would have laid a second finish coat on the doors immediately after the first but I was very new to spraying so I was taking baby steps. 

Thanks guys for all your help.  I'm still on the fence about taking a power sander to the doors.  I figure if I take them outside on a sunny day, turn on the music and pour myself a tropical drink, I can pretend the sand on the paper in my hand is really the beach under my feet.  [big grin]
 
Well using the LS130 would be like hand sanding in straight lines. So if you happen to not be aligned with the grain exactly you will get cross grain scratches.  The orbitals make little "circles" (can't think of a better term) aka wax on/ wax off sort of motion. So do the random orbitals but the pad also turns to make the little circles less patterned. The idea is that the little circles disappear on the finish due to lack of direction.

LS130 linear sander

DTS, RTS, RS 2  orbital

ETS random orbital

Rotex random orbital and rotary

Seth
 
Back
Top