100 grit rule

[mshred]

Hey guys,

Just wondering if any of you guys know what the 100 grit rule is when it comes to prepping a car for paint...a painter at a car show was explaining to me something about prepping the car and using the 100 grit rule for sanding and stuff, but i can't really remember what he said...can anyone refresh my memory, or was it just something that maybe he goes by?

thanks8)

 

[tobysoldblue]

unless he means to finish your putty work with at least 100 grit before primer,maybe?I finish my putty work with 180,and finish my primer with at least 400 wet,if im spraying a solid(non metallic)color,or 600,for a metallic color,to keep the sand scratches from showing through.Ive been doing paint and bopy work for over 20 years,never heard of the 100 grit rule,but then again,im pretty much self taught,lol

 

[pastortom1]

It used to be called the 80 grit rule, until 100 became more available and widespread for long boards..........at least that's how we referred to it......basic 100 was never in the mix.........it was 60, 80, 120, 220, then 400-600 wet.

I still use 80 generally......it's how you final-shape the car with blocks getting ready for the primer coats..........With some high solids over 80, it's nice to block with 100 to expose deeper sand scratches (just fog some black primer over your high solids before you block it.........the black exposes the deeper areas very nicely....takes out the guesswork).

After that, you're ready for some smoother sanding.....(and please use blocks...not a DA (random orbit).......my 2 cents........you can't get a car flat without good blocks). 8)

 

[alleyoopmgv]

It's the 80 grit rule for me, then polyester primer (about 4 or 5 times) with 150 or 180. then regular primer 320 dry,400 dry, then 600 wet, on every car i do. it's alot of work . just painted a 74 roadrunner today(yellow).

 

[3404speed]

Everyone seems to have different preferences, but depending on what you're doing starting with really rough paint or rust/bondo 80,120,220,320 worked for me.
That was good enough for "general production" paint. To make the paint look better with no chance of sand scratches 400 was needed.

Using a DA in the early stages correctly(flat on the surface) is a time saver...too many people try to save more time by using the edges and getting DA waves?

Block sanding with short blocks and Long block is critical and Making your own for curved areas is helpful

 

[whitey]

I used 80 grit on my DA and board sander to remove the paint and surface rust, and to sand down any bondo. I went to 220. I used 2 good coats of primer, then sand with 400/600. I used a two bucket system, one with a teaspoon of dish soap and warm water and one with plain water for rinse; I used 1000 grit, just 2 passes from bottom to top. This smooths out the surface. Going from bottom to top keeps from sanding dirt back into the primer and the plain water is for rinsing then soapy water to sand.

 

[pastortom1]

That bottom to top is a great rule to remember Whitey.......You gotta keep her clean while you're workin' it. :cheers:

 

[mshred]

thanks for the tips guys...I am by no means a body man, but i have no money to pay someone to do it for me so im gonna do the prep work myself and have a guy i no spray it for me