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Re: [oletrucks] Wet sanding

To: BelAir Bob <rogerz@planetwide.com>
Subject: Re: [oletrucks] Wet sanding
From: "A.B." <bigfred@unm.edu>
Date: Wed, 24 Jan 2001 10:55:47 -0700 (MST)
Sounds like good technique overall, but I dont' like to spray a guide coat
on my *final (wetsanded)* primer.  Maybe I'm paranoid, but I dont' like to
mix the chemicals in the spray can paint with the chemicals I'm going to
lay down in color coat.  I was taught that a guide coat is for looking for
highs and lows in the final stages.  After those are all found, the last
layer(s) of primer are layed down and wet sanded with a pad (or block).
When it feels like glass, I know I'm done.  I realize your sanding the
black guide coat off, but it seems sketchy to me... I'm totally *not*
saying your technique is bad, just trying to put out another point of view
for those who are not sure how the final stages of paint prep work.

On Wed, 24 Jan 2001, BelAir Bob wrote:

> Tom,
> There are two stages of the paint process when you can wet sand.  The first
> is the final sanding of the primer coat before painting. The second is after
> the paint has dried before polishing.
> I'm sure others have different techniques for wet sanding but this one was
> taught to me by a buddy who produces consistent show winning paint jobs.
> The pupose of wet sanding the primer is to produce a MUCH smoother paint
> finish.  The technique I use involves a five gallon bucket of warm water, a
> few drops of dish soap, a large sponge, 600 grit 3M Wet or Dry sand paper
> and a can of cheap flat black spray paint.  I do not use a sanding block for
> wet sanding.  The procedure starts by applying a "guide coat" of flat black
> spray paint.  This coat should be nothing more than hazy black stripes a few
> inches, 4" to 5", over the entire piece to be sanded.  You don't want to
> make solid black stripes, they should look a little heavier than just over
> spray would.  The purpose of the stripes is to indicate where you have
> sanded and where you may have missed a spot.  I start by soaking the
> sandpaper for about 30 minutes to soften up the paper.  This makes the paper
> backing more plyable.  The actual process of sanding starts with me cutting
> each sheet of paper into thirds and folding the piece I'm going to use into
> thirds.  I "load" the sponge with water, wet down the area where I'm going
> to start and then begin sanding in a circular motion.  You need to be ver
> cafeful not to sand with your fingertips.  This can cause shallow groves in
> the primer coat.  Instead, keep the paper back under you fingers, say from
> the first knucke down.  This gives good even sanding pressure.  Be sure to
> take off and rings you might normally wear and even trim you finger nails.
> The finger nail thing sounds funny but I have seen "sanding scratches" from
> a buddy of mine that has particularly thick finger nails and bad sanding
> technique. There are times when you will have to use you fingertips to sand
> but just go easy when you do.  As I sand with one hand, I keep a constant
> trickle of water running from the sponge.  You can tell when you aren't
> using enough water when the paper sticks to the surface.  Be sure to dip the
> paper in your water bucket fairly often to rinse of the "sludge" that builds
> up on it.  I continue on in this fashion until all of the guide coat is
> gone.  I finish the wet sanding procedure with a good wash job, water with a
> tiny amount of dish soap,  of the entire piece and a complete drying with
> disposable towels.  In my experience,  if I have done a propper job of
> sanding, the primer will actually have a low shine to it.
> Wet snading the finished paint before polishing is done with the same basic
> technique with a few exceptions.  First and foremost, do not spray a guide
> coat.  Second, at this point I actually sand the entire piece twice, once
> with 1500 grit and once with 2000.  After the water has been dried from the
> sanded piece any area you missed will be glossy.  Once all the missed areas
> are sanded you can polish the paint.  I don't do the polishing so I can't
> comment on the procedure.
> I hope this rather long winded explination helps.
> Robert Rogers
> 57 Belair Sport Coupe restored to original
> 55 -2 3105
> 55 -2 6400
> 55 -2 3100 Wife's project
> 57 3100
> 82/86 GMC Sierra SLE Crew Cab 1/2 ton short bed (For Sale)
> and a few others
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959

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