Newbie paint Q: how smooth does primer need to be? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans Advertise
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Body - Exterior
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-18-2018, 07:12 AM
Registered User
 
Join Date: Aug 2017
Posts: 15
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Newbie paint Q: how smooth does primer need to be?

Hey all, so I'm new to painting car panels, and have a few cars underway that I intend to do with a buddy who has extensive(decades)experience with spray paint, but none with an actual car. I'm doing most of the prep work, and he'll be shooting, as he's got much better hand control. So my question: how smooth do I need to get the primer before shooting base coat? I have completely straight metal, primer on, and have done numerous passes of primer/wet sand to get any imperfections out. what I want to know is this: how critical is the smoothness of the primer in the end product? there are no chips/dings/etc, but the final pass of primer is still straight out of the gun, so it's rough feeling. do i need to thoroughly block the entire car before base coat, or will 2 coats of base "cover" the natural roughness of the primer? thanks for the help!!-RJ

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-18-2018, 08:31 AM
MARTINSR's Avatar
Brian Martin,Freelance adviser
 
Join Date: Jun 2004
Location: San francisco bay area
Age: 60
Posts: 16,147
Wiki Edits: 0

Thanks: 6,240
Thanked 6,696 Times in 4,306 Posts
It depends on how good a job you want. But the primer is generally smoothed out flat in most any situation where a nice job is the end result wanted.

And in fact, perfect flat IS the super basic goal of those who want a nice job. Think about it, you are in complete control, you have the afternoon, the music playing in the shop/garage, a cold drink, and you make it perfectly flat because it's easy, just get it done and that makes the whole job much better.

You don't have to "block" it, sanding it with finer paper with a foam block or nothing at all isn't going to cut waves or anything, as long as you are doing it reasonably correct. The "flattening" done by blocking is done with coarser paper, it is CUTTING it flat. By the time you get ready for paint, just simply "sanding" you aren't using that coarse of paper and you are only removing the texture so blocking isn't needed.

It's so funny, when I think of how much sanding I did "back in the day" on lacquer paint jobs on show winners, OMG. We could sand EVERY SINGLE SQUARE INCH of the surface to PERFECTION. We are talking ZERO texture, not even a single little spec a 1/16" would remain there un-sanded. EVERY SINGLE SPECK of the surface would be the non glossy sanded surface, EVERY SINGLE SPECK of the surface. Ok, here is the funny part for those who didn't do this back then, that is not only how we started to paint, with the primer sanded like that. But after every four or five coats of paint we did it again! And would typically apply 15 coats. So we would do that FULL SANDING of EVERY SINGLE SPECK of the surface after the first five coats, then after the tenth coat and then at the end where it would be sanded perfectly smooth and then polish it to a mirror finish! And I am talking on the cars I did, in the door jambs, firewall, dash board, EVERY SINGLE SPECK of the paint that would be seen would be sanded like this!

Yes, I had no finger prints in those days.

Brian
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-18-2018, 08:34 AM
OneMoreTime's Avatar
Hotrodders.com moderator
 
Last wiki edit: Health and safety in the shop or garage
Last journal entry: Yard Dog pic
Join Date: Jul 2004
Location: Washington State
Age: 74
Posts: 9,579
Wiki Edits: 3

Thanks: 300
Thanked 720 Times in 614 Posts
What we look for in shooting a car is for the paint to lay down what we call "gun done". That is the paint lays out wet and slick with no need to sand other than maybe go over it a de-nib if some trash snuck in. So you may have to reduce the primer about 5 to 10 percent and work on gun adjustment until you get there from here.

https://www.southernpolyurethanes.co...-gun-adjusting

https://www.southernpolyurethanes.co...sting-your-gun

Have fun..

Sam
__________________
I have tried most all of it and now do what is known to work..
Reply With Quote Quick reply to this message
 
  #4 (permalink)  
Old 06-18-2018, 12:32 PM
Registered User
 
Join Date: Jan 2018
Location: Laurel, De.
Posts: 417
Wiki Edits: 0

Thanks: 213
Thanked 165 Times in 123 Posts
Imho, the primer needs to be sanded for adhesion purposes. The base needs "tooth" to stick to unless it is a wet on wet type of primer/sealer application within specific time windows such as an epoxy or 2k sealer. Most paints tech sheets are online so I would look up their prep recommends. Usually 400g minimum for solid color base and 500-600g for metallic bases. No way would I put base down over a cured primer without prep. Just asking for adhesion issues.

Last edited by Hipster_G; 06-18-2018 at 12:38 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-18-2018, 06:10 PM
idrivejunk's Avatar
Grand Prix User
 

Last journal entry: Last look
Join Date: Dec 2015
Location: NW AR
Age: 53
Posts: 3,777
Wiki Edits: 0

Thanks: 4,140
Thanked 4,779 Times in 2,837 Posts
Any unsanded texture not only shows right through basecoat but results in poor adhesion.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-18-2018, 07:03 PM
Registered User
 
Join Date: Dec 2017
Location: North East, Pennsylvania
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I have been prepping cars for a while just throw on three coats of prime and let it dry and then after that block it put some guide coat down you can start with 320 and work your way up I cut all the orange peel out with the 320 then work up to 600 grit to get out all the course scratches
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-20-2018, 10:36 AM
Registered User
 
Join Date: Aug 2017
Posts: 15
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Great info, thanks you guys! Last question for now: how fine should I go on the primer before we start shooting base coat? My instinct says that something in the 1200-2000 grit range would be sufficient, but that's just me guessing. FWIW, I am not out for a $15k looking paint job. I don't want a total halfass garbage job, but I am not intending to put 100+ man hours into a paint job. A nice, solid job that looks good at a quick glance is fine with me. Thanks!
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-20-2018, 11:13 AM
idrivejunk's Avatar
Grand Prix User
 

Last journal entry: Last look
Join Date: Dec 2015
Location: NW AR
Age: 53
Posts: 3,777
Wiki Edits: 0

Thanks: 4,140
Thanked 4,779 Times in 2,837 Posts
600 wet or 400 dry. 1200-2000 is used prior to polishing and is much too fine.
Reply With Quote Quick reply to this message
The Following User Says Thank You to idrivejunk For This Useful Post:
John long (06-20-2018)
  #9 (permalink)  
Old 06-23-2018, 08:05 PM
Member
 
Join Date: Feb 2004
Location: N Ga.
Posts: 859
Wiki Edits: 0

Thanks: 33
Thanked 88 Times in 77 Posts
Depending on the color, I usually go 400 to 800. 400 for solid color (white, black, red, etc) 600-800 for metalics, and BC pearls. 800 for light metalics, and BC pearls. for 3 stage pearls I've found 400-600 to be sufficient, as the base color will fill the sanding prior to the pearl coat.
I've also been known (if out of finer paper) to spray a coat or two of 895, or Base Fix, (what amounts to clear base) before applying color, especially light metallic such as silver, and light blue.
Also, when out of "scuffin' stuff" I've been known to use 800-2000 to prep for blend. Works quite well.
As does Comet, or Ajax.
Reply With Quote Quick reply to this message

Recent Body - Exterior posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Insurance
Please select your insurance company (Optional)

Log-in



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
anti stone chip smooth primer on early fenders ,want nice finish carfan Body - Exterior 13 06-16-2012 10:31 AM
anyway to get primer fillers to spray smooth proge Body - Exterior 3 05-18-2009 11:53 AM
intake manifold i plan to sell, should i polish it, or smooth it for paint lowROLLERchevy Hotrodding Basics 4 02-10-2006 10:40 AM
what is best to smooth body to paint wiretwister Body - Exterior 3 12-24-2005 07:17 AM
Newbie question-primer bluebu Body - Exterior 16 03-24-2005 09:34 AM


All times are GMT -6. The time now is 05:21 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.