IML - DIGEST POSTING

[Mark and Theresa Elliott <deadfishe@xxxxxxxxxxxx>]

I am rather new to this body work thing.  What grit of sand paper should I 
use for various tasks?  For example, most of the paint on the front of my 
car isn't in too bad of shape, and I primarily want to get it ready for 
painting.  The back half of my car on the other hand seems to have more of 
a rust problem that I was expecting.  I don't see any rust bubbling through 
paint (except in the areas that caused me to start this adventure), however 
as I am sanding I occasionally go all the way to bare metal and find rust 
(or possibly the remnants, as it looks more like rust that someone as 
already killed or at least sanded/sandblasted).  Because of how much of a 
pain this is, I think I would prefer to take the back of the car all the 
way down to bare metal and make sure that the rust is taken care of now 
rather than doing it all over is a few years when the rust that I didn't 
find starts coming through the paint.  Anyway what grit of sand paper 
should I be using for this.  I have been using 220 grit for everything 
(except the areas where I know that there is lots of rust, most of which 
will need to be cut out anyway).

Thanks
Mark Elliott
64 Crown
76 Fleetwood Brougham

>From: "Junior the Mean Widdle Kid" <rrudd28@xxxxxxxxx>
>Subject: Re: IML: removing paint
>Date: Fri, 19 Jul 2002 00:01:46 -0500
>Reply-To: mailing-list@xxxxxxxxxxxxxxxx
>I remove paint/primer from cars almost on a daily basis.  The main thing you
>want to look at when you're removing paint is the end goal of what you wish
>to accomplish.  Even when it comes to removing paint for prep/repair, there
>are different methods, some of which you do not want to do in certain
>situations.
>
>The easiest by far is chemical "aircraft" remover.  I do not recommend this
>as it's quite the nasty job.  The chemicals are volatile, the chemicals used
>are harmful to just about everything not man-made, and these chemicals need
>to be completely neutralized lest they come back and destroy your paint job.
>If you absolutely have to do this, take it to a professional and let them do
>the dirty work and let them deal with the EPA.
>
>If you're stripping paint to repair rust, the best that I've found is a 24
>grit grinding wheel.  I use a CP pneumatic 7" one, though, this can be
>rather big for confined areas.  You can use smaller size wheels found at
>paint and body stores, Lowe's, Home Depot, and Sears.  This is the fastest
>and most effective way to remove everything in preparation for welding or
>making a fiberglass patch panel.  Unfortunately, after you use this, you'll
>need to sand it with a DA or file sander and work from 36 grit to 180 grit
>as 24 grit scratches will show through paint and primer.  Another big
>drawback is that these grinding wheels generate a lot of heat and can warp
>panels if you let it build up.  If it's glowing red, and it's not a weld
>you're grinding down, you're running it too hot for stripping paint.
>
>If you have surface rust, and wish just to sand it down to bare metal the DA
>works best.  A random orbit is okay, but I have  DA and not a random orbit
>so I use the DA.  For this, you want to start off with 60-80 grit and work
>your way up to 180 grit.  Then, block sand it with 220, then primer.  Then
>sand with 400 then 600 to prepare for paint.   Most quality DA's are
>adjustable so you can control the speed of material removal.  My IR
>'handle-style' DA will strip to bare metal at full blast and 80 grit in
>under 10 seconds.  My hand held Hutchins will do a similar job in about a
>30.
>
>If you're in a tight spot, the de-rusting wheels are around 24 grit, and do
>a fine job if you're cleaning up a seam you wish to weld a panel upon.
>
>Now, this is a little known fact, but there are 2 different kinds of
>sandpaper.  There's "American" and "European" standard paper.  This is
>extremely important!  American sandpaper, primarily made by American
>companies (Norton, 3M) has a number only (80, 180, 220 et al).  European
>paper, specifically Mirka (Finland) has a "P" designation before the number.
>This "P" actually means that the paper is about 1 grade less than American
>paper.  By grade I mean that if you had 80, P-80 would be roughly 60 grit.
>I didn't know this till a PPG rep told me about it.  Sandpaper is sandpaper,
>and the better brands are going to be comparable in quality.  Auto sandpaper
>should be wet/dry if purchased in sheets.  Self-adhesive paper (purchased
>for round DA's etc) isn't always wet/dry.