From this article,
Damp-Sanding Tools, Tips and Techniques by Mike Phillips
Taping-Off, Covering Up and Removing Trim
As a rule, it's a good idea to tape-off any raised hard body line for two reasons,
- So you don't sand over the high points
- Simply so you can see where they risky areas are at on a panel
1. So you don't sand over the high points
Paint will tend to be thinnest on any high point as the forces of gravity will cause the paint when it's sprayed and thus a liquid to flow downward. It only takes a few seconds of sanding on any high point, edge, corner or raised body line to either sand through the topcoat or remove enough material that when you later compound the area you go through the topcoat while compounding. So taping off high points will save you from having to repaint a panel.
2. So you can see where they risky areas are at on a panel
This one might sound kind of dumb if you've never sanded down an entire car before so let me share with you why it's important. As you're sanding, you'll create a white slurry on the panel that you can't see through. This slurry is made up of particles of paint you've removed off the topcoat, mixed with water. As it covers the panel it hides or camouflages everything under it including a high point or raised body line. By placing some tape over the area you want to avoid you create a visual indicator or reminder of where not to sand.
Here you can see where I've taped-off the edge of the gas tank door and the sheet metal surrounding the opening for the gas tank door. This will protect the edges while sanding and compounding.
Body lines taped-off
If you look carefully you can see some thin tape lines running down the center of the hood and the middle of each half-sections of the hood, these are
raised body lines as a part of the styling of the hood. They are not very high off the surface and when sanding,
the entire area will become white with water slurry. By taping them off I could see where they were at and if I accidentally run the sander too close to them, no worries...
Thin tape on top of raised body lines on the hood
Grills and Vents
It's nearly impossible to get under the fresh air grill on late model cars to remove splatter residue so I always carefully tape them off. Sad to say but whoever sanded and buffed this car before me plastered the area under the tape you see here and there's no practical safe way to remove it so it will forever be an eyesore when the owner shows this El Camino
Fresh Air Grills Taped-off
Here you can see where I've taped-off any edge I didn't want to risk sanding over... and it's not that I'm not good at what I do it's because the next paint job I buy is going to be for me.
Also tape off any trim you cannot or will not remove, especially plastic, rubber or felt trim and gaskets. This goes without saying but just to say it or type it, the reason you do this is so you don't damage the material while sanding and buffing and so you don't cream it over with compound or polish residue which later can be a nightmare to remover and cause the owner of the project vehicle to use your name as a curse word the rest of your life.
On classic cars, trim, script and emblems can be very fragile, especially the studs and nuts that hold them to a panel. What I personally like to do is point this out to the owner of the car and ask if they can and are willing to remove them so I can do a better job of sanding and buffing out their car. If they say "yes", this puts the responsibility on them for any damage caused by removal.
The good news is that often times owners of special interest and classic cars will already be very familiar with these items and understand the risk and in some cases be very proficient at their removal since they are more intimate with their car than you are.
If the owner cannot or will not remove trim, script or emblems then you can opt to remove them yourself as carefully as possible and/or tape or cover them up.
Covering up
I like to cover up the engine on special interest cars and especially show cars or restored cars where the engine and engine compartment are clean enough to eat off of. The reason for this is because it's all to easy for stray splatter from either wet-sanding or machine compounding and polishing to spray onto the engine and engine compartment and cleaning these areas can be difficult and very time consuming.
Here's a video I made a number of years ago that explains
why to cover an engine and shows my method of using a clean,
soft flannel bedsheet to carefully cover and protect the engine. You can also do this for trunks and interiors if you're working on a convertible with the top down or off the car.
Covering the motor on the Panic Parrot
[video=youtube_share;sE_0W-VXjR4"]YouTube- Covering the motor on the Panic Parrot...[/video]
To tape-off and cover areas and items on a car you'll need things like a good selection of Painter's Tape.
Also I like to have 2 mill Plastic Painter's drop cloths on hand, tin foil, and even a Beach Towel to cover up windshields and wiper assemblies in one fell swoop.
Canvas Wheel Covers
Wheel Covers make fast work of covering and protecting custom wheels and tires, don't kid yourself, wiping off any splatter from a well dressed tire or an intricate wheel design will be time consuming and not very much fun. Besides Canvas Wheel Covers like body shops use I've also used large Glad Garbage bags, like the kind you get for leafs and yard debris, you can slit them on one side and then slide them over the wheel and tire and tape back any loose plastic. I've also used newspaper to create a makeshift cover with tape as seen here,
Whatever it takes to keep the tire and wheel clean and keep me from having to wipe off any stray splatter is my personal goal.
I love polishing paint but I hate detailing cars. (See the link below to see what that means)
"Polishing paint is polishing paint, detailing is getting the wax out of the cracks"
