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+-- Thread: sanding "Polycrilic"??? (/showthread.php?tid=7238396)
sanding "Polycrilic"??? - Wild Turkey - 03-08-2016
I'm "re-purposing" ( at LOML's instruction
) a buffet into a vanity.Plan was to coat top with Polycrilic water-based poly to avoid fumes, etc inside.
Working on third coat and I'm sanding with 320 wet or dry sandpaper on sanding block between coats and I'm getting gobs of finish rolling up on the paper.
Finish had dried overnight.
I dusted the sandpaper off and wiped off the surface and all was well for a couple of strokes, then it started loading up again.
Is this a problem with Polycrilic or am I doing something wrong???
Re: sanding "Polycrilic"??? - jteneyck - 03-08-2016
That's one of the reasons I don't like Polycrylic. It's soft compared to GF's WB products, which you can sand after only a couple of hours. Try regular, stearate coated sand paper rather than wet and dry. The stearate coating on it helps keep it from loading up. 400 or 600 grit might work better, too? Not sure. Also, what temp. is it where you are applying the finish and letting it cure? Most WB's need at least 60F and preferably 65+ to dry/cure properly.
John
Re: sanding "Polycrilic"??? - JR1 - 03-08-2016
You can scuff sand Crystalac or the GF waterborne finishes at around an hour between coats. But you can't sand back between coats or rubout until its cured around 72 hours. These finishes usually must be applied and maintained between 60 and 85F until cured.
I've had folks who use Polycrilic tell me that you can only hand sand very lightly between coats.
I would not use stearated sandpaper without trying it on some scrap. IME stearated sandpaper is incompatible with waterborne finishes.
Re: sanding "Polycrilic"??? - jteneyck - 03-08-2016
JR1 said:
IME stearated sandpaper is incompatible with waterborne finishes.
That may be your opinion, but it's not shared by Jeff Jewitt or Bob Flexner. Both say they have studied it and found no issue, nor have I with the WB products I've used.
John
Re: sanding "Polycrilic"??? - JR1 - 03-08-2016
Possibly I was just unlucky or more likely didn't get all the soap off well enough. Still I don't see the advantage of using a sandpaper optimized for commercial NC shops with a waterborne.
Re: sanding "Polycrilic"??? - Howard Acheson - 03-08-2016
>>>> I'm getting gobs of finish rolling up on the paper.
That's call "corning'. It's the primary indicator of a "not yet fully dry" coating. A fully dried coating should produce white powder when sanded or a white paste when wet sanded.
An old finish material will take longer to fully dry. Finally, waterborne finish should not be built up to too thick a film coat.
Re: sanding "Polycrilic"??? - bhh - 03-09-2016
I've been using 3M's 216u (aka "Sandblaster") paper for the last dozen years with several brands of w/b finish with no problems. It is lubricated, but my chemistry knowledge is stale, so I don't know if you would classify it as "stearated" or something else.
And Howard is right -- not fully dry/coalesced.
jteneyck said:
[blockquote]JR1 said:
IME stearated sandpaper is incompatible with waterborne finishes.
That may be your opinion, but it's not shared by Jeff Jewitt or Bob Flexner. Both say they have studied it and found no issue, nor have I with the WB products I've used.
John
[/blockquote]
Re: sanding "Polycrilic"??? - mad_planter - 03-10-2016
It will load up no matter what you do, but it shouldn't that fast if its completely dry. Wet sanding works really well, just go real easy. I'm doing all the trim out of my new house and have so far applied 3 gallons of the stuff, 3 coats each.
It occurred to me that I had something similar happen at the beginning when I was finishing up a gallon of it that I had sitting around for a while, but on the new cans I don't get any pilling like that. Is the polyacrylic you are using old?