Fine Sandpaper Versus Non-Woven Abrasives

Here's some discussion about when to use sandpaper and when to switch to synthetic scuff pads, and why. October 17, 2012

Question
I'm having a hard time scuff sanding primer with Scotch-Brite. Maybe my primer is overly hard or I'm using the wrong pad. Everyone here states they scuff with the grey pad which is equal to 00 steel wool. I've switched to 220 completely. What do you use the grey pad for? It more or less buffs the finish versus scuffs it. Maybe a "0" pad would be better? Is that one brick red? I believe the 00 is even finer than 320? Can I get away with the 00 between the coats of pigmented poly?

Forum Responses
(Finishing Forum)
From contributor B:
With a primer coat, I find the scuff type pads a bit too fine to do much good, especially on the initial coats. I dump the beginning primer coats on and let them dry really well, then grind on it with 220/280 to cut it way down. The Porter Cable square base sanders work real well for this step.

Once everything is sanded to perfection, including any profiles, I apply a few thinner coats of primer and let it dry up well. Then, I grab one of the scuff pads and impeccably scuff the profiles to rid them of any nibs or flaws.

Once satisfied the base coats are flawless, I proceed with the color coats.



From contributor C:
I've been using the Mirka Goldflex 240 for the initial leveling, and those 1/2" two-sided flexible sponges for carving, spindles, etc. The Scotch-Brites don't cut like paper.

From the original questioner:
Thank you. Sanding these beads in the FF stinks. I was worried about adhesion.

From contributor E:

Sandpaper cuts flat, Scotch-Brite (non-woven abrasive) burnishes. The platen of a sanding block or quarter pad orbital folded in your fingers will cause the paper to cut into the sealer/primer or finish to remove high spots (orange peel or junk) and other damage. Non-woven will polish or burnish the scratches left from your sandpaper. Equivalent grit will not do the same function. Most sanding sealers or primers that we do are sanded with 280 Klingspor PL36 then with a pneumatic pad sander with medium (maroon) non-woven. Prove it to yourself on the same primed surface. Sand one section with 280 and the adjacent section with Scotch-Brite and you will see that they do not perform the same function.

From the original questioner:
Would I need the Scotch-Brite for any purpose? Do I need to burnish after the sanding? It sounds like 220, 320 is the primary tool for both primer and paint between coats.

From contributor C:
We use it for really tight proud detail, tadpole carvings, small finials, sometimes edges. Sometimes when glazing in a high contrast situation, we go over the sanded surface with backed Scotch-Brite in full even strokes, thinking that we thereby refine the etch pattern to improve the glaze lodge - maybe it's just a device for us to procrastinate a little longer before diving into something difficult. We also use it to cut the tarnish off old hardware, clean tools and fluid nozzles and as a perch to keep snacks off the slobber on the color bench.

From contributor E:
Some of us have been around before 3M brought nonmetallic steel wool to the market, so lots of finishing was done with just 320. It has allowed us drop down to 280 for a faster cut then finish up quickly to remove sanding scratches that your finish may not saturate into. Try back to back samples. For my finish production I believe that it is worth the extra few seconds that using Scotch-Brite (non-woven) abrasive gives you, especially around carvings, corners and details. Jim, you are right about using it for breakaway glaze knockdown. Most have an added abrasive particle that will leave black particles if not removed before finishing.

From the original questioner:
I've been using 220 to break down my primer coat(s). Should the last/2nd coat of primer be taken down with 320, as there is little to no raised fuzz on this coat?

For pigmented topcoats, I'm using GF poly. They recommend 320 and I was just planning on sticking with that.

Do any of you know if the waterbase polys melt into each other or is it all a mechanical bond? I am wondering if, due to leaving a 3rd coat until the next day when I have more time to deal with finalizing some finishes, you have a window?



From contributor F:
I've been using 280 grit to sand all of my finish coats. The manufacturer recommends 400, but I find it just clogs too fast and takes too long to get where I need to be.

I've found the maroon Scotch-Brite pads are great for removing rust off of cast iron machine tops. I bought a couple machines that have some light rust on the tops and those pads with a little WD40 worked great!

I've been buying sandpaper from Hafele recently. They came in one day with the sales pitch and their pricing was way below what I had been paying.



From the original questioner:
I'm never going to finish an installed kitchen, it took 3 hours to sand each coat, crown to ceiling, beaded, and raised panel ends. It is more than furniture grade, all the ends are mitered to the face frame stiles and scribed to perfection on walls, etc. My back is killing me.

From contributor F:
GF is asking for 3 coats of primer. I have 2 nice coats and no wood showing. Is there a need for the third? Primer is basically a moisture block for top coat as it is semi-permeable, and used for paint adhesion. That said, if itís opaque, I'm good to go, I assume. Any of you work with GF undercoat?

From contributor G:
My schedule for GF pigmented is two coats primer, two top coats of poly (1 primer coat and one topcoat for backs of drawers/doors) . Around the sink, dishwasher area you may want to add a 3 top coat for added durability. I hit the 1st coat of primer with 320+ Scotch-Brite, later coats 400+ Scotch-Brite. If the finish is fresh you really don't have to Scotch-Brite, as long as your sand job is good. I've always done it that way. Most WB's are mechanical bonding.

Also on your built-in crown, mouldings, inset panels, door details, I would only lightly sand those and just the first coat of primer. For ensuing coats, I'd just hit them with Scotch-Brite.