Skim Coating

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On Thursday, January 24, 2013 10:26:12 PM UTC-5, Larry Jaques wrote:
is called fast-build >> primer surfacer or "sanding primer". > > >Judging f rom his photos, I don't think those would even *begin* to smooth >his parti cle board. Not without many, many coats at least. Half the roughness appear s to be the adhesive left from the contact paper. Sanding that off is near to impossible. BTDT, struck out.
No actually the "rough" areas are where there is the least adhesive. Pullin g the original vinyl off took with it miceoscopic particles of the particle board leaving behind the relatively rough areas. The relativiely smooth ar eas actually have more adhesive residue left behind.
The pics where taken on the Macro setting. So I guess it looks worse than i t is.
I tried the drywall mud a couple more times and it is really difficult not sanding too much back off. By the time I get the ridges down the "rough" ar eas start to show again. (I'm about to give it another shot).
Hand sanding is too work intensive so I've been trying my orbital and also my finishing sanders.
Darren Harris Staten Island, New York.
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wrote in message

The problem is likely the difference in hardness between the joint compound and the "wood" and having a relatively soft backer behind the sandpaper on the power tool. It's not much different from what happens when sanding fast growing pine in that the hard annular rings stand proud of the softer areas between them after sanding. It is for this very reason that I use plaster of Paris, not drywall compound, as a surfacer/filler. Plaster is harder and closer to the "wood" density than is drywall compound. Using a thin coat of plaster, a relatively long sanding block, and hand sanding would be the way to get a flat smooth surface. Starting out with power sanding and finishing by hand is viable too. Yes it might take longer than using power sanding alone but how many times do you want do to it? With oil based clear finishes this works well as the plaster becomes translucent and disappears. Drywall compound does not yield a similar appearance under clear oil finishes in my experience as it has more than just plaster with water in it. Under sanded primer and paint it yields a very fine finish.
An alternative that works reasonably well is to use the drywall compound, sand it to nearly finished, apply thinned polyurethane or dewaxed shellac as a sanding sealer to firm up the compound, and then finish the sanding by hand. This works pretty well under sanded primer and paint but I'd not use clear oil finish on it.
John
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On Sat, 9 Feb 2013 17:23:50 -0500, "John Grossbohlin"

Another good option is 50/50 polyfilla and plaster of paris. Not as hard and fragile as straight plaster of pasis, but doesn't shrink like plyfilla alone - or drywall compound. Also cures fast!!!!

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On Sat, 9 Feb 2013 13:25:19 -0800 (PST), snipped-for-privacy@mail.con.com wrote:

> snipped-for-privacy@snyder.on.ca wrote: >> Use the product that is MADE for the job. It is called fast-build >> primer surfacer or "sanding primer". > > >Judging from his photos, I don't think those would even *begin* to smooth >his particle board. Not without many, many coats at least. Half the roughness appears to be the adhesive left from the contact paper. Sanding that off is near to impossible. BTDT, struck out.

the original vinyl off took with it miceoscopic particles of the particle board leaving behind the relatively rough areas. The relativiely smooth areas actually have more adhesive residue left behind.

sanding too much back off. By the time I get the ridges down the "rough" areas start to show again. (I'm about to give it another shot).

If you are going to use the mud, the only really effective way to sand it is manually with a samding board. Use half sheet sanding screen - 120 grit. Half sheet long ways.
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On Sat, 9 Feb 2013 20:12:19 -0500, "Mike Marlow"

I guess he doesn't know what WORK is.
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On 12/21/2012 5:35 PM, Searcher7 wrote:

Zinsser Bulls Eye 1-2-3 Primer/Sealer
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On Friday, December 21, 2012 3:35:07 PM UTC-8, Searcher7 wrote:

Not OK. It's expensive and time consuming, and using particle board with a preapplied paper layer (MDO, the 'O' is for overlay) is the better solution.
Particle board is 100% endgrain, it's a finishing time sink without any redeeming moral or aesthetic value.
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