Sanding Between Polyurethane Coats with Festool Sander?

laanguiano

laanguiano

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Joined
Nov 1, 2012
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Does anyone use a Festool Sander between Finish Coats of Polyurethane?  If so which sander, what grit paper, etc etc. 

I tried using my Festool ets150 with 320 grit Brilliant at 1x speed, but it left small scuffs in the finish that didnt come out with the next polyurethane layer.

What do yall think? 
 
It's more important to look at the other details you didn't provide, such as...

What poly are you using?
How are you applying it?
How long did you wait before sanding?
Are you loading up the paper at all?
How long did you sand?
Is it heating up while sanding?
 
I use the hand sanding block.

sanding block

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I use wipe on poly and sand after every second coat.  I use a sanding block with 320 grit paper.  Bill
 
I assume that you are using normal polyurethane...

When I used to use this type of finish I would very lightly hand sand between coats, using a block with either 240 or 320 grit. The purpose of the sanding at this stage is to remove any nibs (sticky up bits due to dust etc) and also to provide a key for the next coat. The sanding is so light that I refer to it as "kiss" sanding.

Peter
 
For small areas I just hand sand very lightly.

    For larger I use the ETS150/3 (used to use the /5) with 320 or 400 Brilliant. Speed 6. You might try going as low as 4 if you want a little room for error.  This is on oil based polyurethane (oil based by definition really).  I generally do two coats before sanding. Sometimes one coat for brush on. But for spray or wipe on (especially wipe on) two coats for sure other wise you risk sanding through. Same goes if I have stain underneath ..... at least two coats (three for wipe on) before sanding to ensure not sanding into the stain. You basically need enough poly on the surface so that you can actually sand thoroughly with going through.

    Make sure the poly is thoroughly dry. You should be getting white powdery dust and surface appearance when you sand. I think the speed set at 1 is not helping. You probably are not getting a thorough sanding. I find that I need to not dwell with the sander but still make sure all areas get sanded. After you sand, clean the surface off  if you see any spots with sheen re-sand those. If you see areas with swirls , re-sand those too.  If you see little "flecks" that have a sheen, those are small pits in the surface. As you apply and sand successive coats they will start to fill in and disappear.

Seth
 
I was using GF arm-a-seal semigloss, 1 coat with thick foam brush layer, let dry for 24 hours.  I didnt see any of the stain get lighter so i doubt I went through the entire finish.  Maybe I needed a higher grit,  You only see the scratches with a raking light.

Also here's another one.  So I wiped off the white dust with a lint free cloth, there was still a good amount (I probably should of just left it and put another coat of poly) but i decided to use a damp rag to remove the rest.

Should I of used mineral spirits or water to dampen my rag?  Or does it not matter which?  And just for added info, I had water based stain underneath the poly but that should have been sealed by the poly.
 
I generally vacuum and then also wipe with mineral spirits.

Seth
 
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