3M sandpaper

[bases-loaded@juno.com]

HI Terry -

Any place where one grit's scratch pattern did not get completely
replaced by the succeeding grit's pattern, will show up as a slightly
hazy spot in your rubbed out topcoat.  In other words, when you finished
with the 800, there may have some 400 scratches that didn't get replaced
by the finer 600 grit, and the 800 didn't completely remove them either. 
That would be my best guess, although there are other possibilities, of
course.

I use a similar method of 400, then 600, but I only go to 800 if it as a
filled pore satin finish.  Otherwise, I go from 600 to the gray
scotchbrite, and usually finish up with 4/0 wool.  I use both the
scotchbrite and the wool with some rubbing lubricant (wool lube, wool
wax, Murphy's Oil Soap, etc).  I think it helps produce a more even
sheen, and a slightly higher one than using them dry.  Finishing with the
gray pad is certainly fine, but will be slightly flatter in appearance
than moving up to 4/0 wool.

As far as fixing your milky spot, you will have to go back to the grit
required to bring that section back up, then to the successively finer
grits and to the gray pad to match the sheen that you have established in
the surrounding area.

I am more and more finding myself using the Abralon pads in the rub-out
phase.  They are circular pads meant for a random orbit sander, and in
fact I do sometimes use them that way, esp. to level the big lid.  They
come in grits of 500, 1000, 2000, and 4000  (pretty sure).  I have mostly
been using them by hand on a flat chunk of wood as a final pass to
produce an extremely even scratch pattern.  They are pretty amazing in
that you just rinse them out and use them over and over again.  I have
literally rubbed out the last two grands with one pad!

There's something new around every corner.

Mark Potter
bases-loaded@juno.com
  
On Wed, 16 May 2001 08:26:20 -0400 "Farrell" <mfarrel2@tampabay.rr.com>
writes:
> Hi Mark. My first PSL piano - after a lot of sanding orange peel - 
> has
> turned out quite nice. One question regarding the final rub-down for 
> a satin
> finish. I sanded through with 400 grit fre-cut gold, followed by 
> 600, and
> then 800 grit. Then I rubbed it down with the medium (gray - 400 
> grit type)
> 3M Scotch-Bright pad. Most of it looks real good, but some areas 
> (maybe
> where I rubbed a little harder) have a bit of a milky appearance. It 
> is
> definately not the clear finish that is milky - it was very clear 
> before
> sanding - but rather a bit of a milky haze apparently from the final 
> rub-out
> with the Scotch-Bright pad. Any ideas how to fix? How do you do your 
> final
> satin rub-outs on the Oxford PSL?
> 
> ----- Original Message -----
> From: <bases-loaded@juno.com>
> To: <pianotech@ptg.org>
> Sent: Wednesday, May 16, 2001 8:13 AM
> Subject: Re: 3M sandpaper
> 
> 
> Hi Greg -
> 
> I have used the 216U paper you refer to exclusively for the last 4 
> pianos
> I have refinished, and I find it to easily be the best paper I have 
> ever
> used.  I also have used Oxford's Premium Spray Lacquer on many 
> occasions
> and have not had the trouble that you experienced.  I have found 
> that it
> can be sanded safely, although somewhat gently, after a couple hours 
> with
> no problem whatsoever.  Rubbing out after the final coats, though, 
> is
> another matter.   At least a week is preferred, and two is even 
> better,
> IMHO.
> 
> I can only surmise that either:
> 
> 1. the coat you applied was extremely heavy, in less than ideal
> conditions, and still had a soft belly after 24 hours;
> 2.  There was a contaminant left on the board that didn't allow the 
> PSL
> to dry properly;
> 3.  You are pushing down way too hard when sanding.
> 
> It is a good idea when sanding finishes between coats with dry paper 
> to
> keep a piece of T-shirt handy to wipe off any accumulation on the 
> paper
> every so often.  It will flake right off and prevent any build-up 
> that
> will compromise your paper's ability to provide a good, even scratch
> pattern.  For the same reasons, wiping off the surface you are 
> sanding of
> accumulated sanding dust is also beneficial.
> 
> Mark Potter
> bases-loaded@juno.com
> 
> On Wed, 16 May 2001 00:28:36 -0400 Greg Newell 
> <gnewell@ameritech.net>
> writes:
> > Dear Lists,
> >     Not too terribly recently I read of the benefits of 3M's 
> fre-cut
> > gold sand paper. I recently bought some from Jeff Jewitt who told 
> me
> > to
> > use it between coats of Oxford Premium spray lacquer. I found that
> > it
> > began to remove some material and that material then balled up and
> > began
> > to cut grooves in my new soundboard finish! YIKES! I waited at 
> least
> > 24
> > hrs before sanding between coats. Should i have waited longer? Is
> > there
> > a better way to use this highly acclaimed product? Are there
> > different
> > uses for this paper rather than between coats? I assume that it is
> > used
> > dry as it is a paper backing. Is that right? All was saved with a
> > scotchbrite pad and some careful rubbing. I applied the decal and 
> am
> > now
> > ready at my next opportunity to spray over it. So far it looks
> > great!
> >
> > Greg
> > --
> > Greg Newell
> > Greg's Piano Forté
> > 12970 Harlon Ave.
> > Lakewood, Ohio 44107
> > 216-226-3791
> > mailto:gnewell@ameritech.net
> >
> >
> >
> 
>