Importance of sanding, sanding, and more sanding
 

Most people don't understand what it means to really get the body right on an old car. I usually sand an entire car out 4-5 times before finally painting. Last night really drove that point home for me.

I've been working on this Mach 1 Mustang for over a year and a half now...car was a mess when I got it. Not a single straight panel. Last night I was sanding it out for what I thought was the second to last time. As I was sanding the back half of the roof I found a nasty wave in it still....about a foot and a half long by a foot wide area. Guide coat didn't pick it up because it's so big that my sanding block follows the contour. And when it's in primer you can't see it. Developing a feel for the body lines of a car while you're sanding is very important. If I hadn't felt that wave last night I would have painted the car next week and as soon as there was clear on it, the wave would have stuck out like a soar thumb, especially on the roof.

So some tips....always sand with the longest block you can, especially when doing your bodywork. You can go down to a small rubber pad for your final wet sanding. Use guidecoat atleast twice. And on large flat areas always run your hand across the panel in numerous directions to make sure you don't feel any waves. You don't want to have to go back and reshoot a large area and worry about blending clear in.....just not worth the headache.

Great advice Paul. Its true, it takes forever, but the end result is what makes the difference.

Good catch! What's 'guide coat?' Primer? First time I've heard this term, and it sounds really important!

There's a whole other thread on guide coat but essentially it's a powder or spray that you put on top of your primer...looks like a misted on coat of black. Then you sand and if you have any low spots you'll still see the black when the surrounding areas are clean.
Not sure if you were asking about primer too....but it's basically a type of paint you use to seal in any previous paints if you use a primer/sealer. It also has much better adhesion than regular paint and is used between your bare substrate and your color to help promote the physical bond between the paint and the car.

So I could walk into a paint shop and ask for guide coat and they'd know what I'm talking about? Also, do you need a certain type of spray gun to apply it, or does it work with any automotive gun? Forgive the newbie questions, but I'm thinking of at least priming my car when it's reached that stage of the build.

you can get guide coat in a rattle can

This is what i ordered from Eastwood. (haven't used it yet).

http://www.eastwoodco.com/shopping/p...ProductID=1852

Oh my God they charge $11 a can for that stuff??!! I buy the same eact stuff at my local paint supply place for $5 a can. Eastwood always has and always will be a ripoff.