Why is primer cracking - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



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

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 09-20-2004, 04:12 PM
Member
 
Join Date: Feb 2003
Location: Weatherford Tx
Age: 73
Posts: 168
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Why is primer cracking

The cab of my 54 Chevy was dipped and stripped then sanded with 120 grit and then shot with Dupont 615s Veriprime and
then with 4004s Dupont primer. While i was block sanding i noticed cracks in all the small inside corners that go all the way
to the metal. Did I do something wrong.
Thanks
Loy
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 09-20-2004, 04:15 PM
poncho62's Avatar
Out of the Loop Moderator
 
Last wiki edit: Streetbeasts links
Last journal entry: at car show
Last photo:
Join Date: Oct 2003
Location: Hanover, Ontario, Canada
Age: 61
Posts: 16,791
Wiki Edits: 5

Thanks: 19
Thanked 238 Times in 194 Posts
Did you "etch" the bare metal with metal prep?


Should have.
__________________
Ontario Rodders
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-20-2004, 04:23 PM
Member
 
Last photo:
Join Date: Apr 2004
Location: Georgia
Posts: 3,573
Wiki Edits: 0

Thanks: 10
Thanked 57 Times in 36 Posts
This can be a common (well, does happen sometimes) occurrence with either acid etch or epoxy.
If you look at the areas cracked its normally areas that receive overlap coats. In other words if you put two coats on the door and two on the fender than two on the rocker the front corner of the rocker got about six coats (with over laps)
Normally there may be two or three spots like this on the whole car and you can just sand those spots down and re-primer.

Short of the story is solvent were trapped in the acid etch (acid etch is made to be sprayed thin) and now are trying to come out and its shrinking as the solvents dissipate.
I should add, this never shows up until you primer and it re-flows the top coat that sealed in the solvents.

Last edited by BarryK; 09-20-2004 at 04:48 PM.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-20-2004, 04:23 PM
Member
 
Join Date: Feb 2003
Location: Weatherford Tx
Age: 73
Posts: 168
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Poncho
The 615s Veri Prime is Duponts self etching primer, Is that what you had reference to ?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 09-20-2004, 04:56 PM
poncho62's Avatar
Out of the Loop Moderator
 
Last wiki edit: Streetbeasts links
Last journal entry: at car show
Last photo:
Join Date: Oct 2003
Location: Hanover, Ontario, Canada
Age: 61
Posts: 16,791
Wiki Edits: 5

Thanks: 19
Thanked 238 Times in 194 Posts
Quote:
Originally posted by BLOWN 1100
Poncho
The 615s Veri Prime is Duponts self etching primer, Is that what you had reference to ?
OK............wasn't aware of that.
__________________
Ontario Rodders
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 09-20-2004, 06:03 PM
Muscle car fan
 
Last photo:
Join Date: Mar 2003
Location: Manitoba, Canada
Posts: 865
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally posted by BarryK
This can be a common (well, does happen sometimes) occurrence with either acid etch or epoxy.
If you look at the areas cracked its normally areas that receive overlap coats. In other words if you put two coats on the door and two on the fender than two on the rocker the front corner of the rocker got about six coats (with over laps)
Normally there may be two or three spots like this on the whole car and you can just sand those spots down and re-primer.

Short of the story is solvent were trapped in the acid etch (acid etch is made to be sprayed thin) and now are trying to come out and its shrinking as the solvents dissipate.
I should add, this never shows up until you primer and it re-flows the top coat that sealed in the solvents.
this is an occurrence with epoxy just buy it self??
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 09-20-2004, 07:34 PM
Member
 
Last photo:
Join Date: Apr 2004
Location: Georgia
Posts: 3,573
Wiki Edits: 0

Thanks: 10
Thanked 57 Times in 36 Posts
Quote:
Originally posted by Dubz
this is an occurrence with epoxy just buy it self??
************************************************** **
I don't think, it can happen buy itself. I should say never have herd of it happening. Here is why.
The net result is to much product to fast (not enough flash time)as is the case with the overlap coats. By itself after the top coat skims solvent will at a retarded rate seep out but very slowly.
Now the immediate coating of another product such as paint or 2K primer will melt the top coat and solvents start flowing at a faster rate and normally the cracking will show up next day from contraction.
I have had one spot do this to me in 30 years and it was on the inside of a front fender a spot that I slipped with the gun when I was spraying epoxy and a few days later after I based it a 2 inch split appeared.
I do hear of this on and off but usually its when product is applied in real hot weather or in cold conditions.
Barry
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 09-20-2004, 07:37 PM
Member
 
Join Date: Feb 2003
Location: Weatherford Tx
Age: 73
Posts: 168
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
How long does this take for all the cracking to stop, it has been
about two weeks since the last primer was shot.
Loy
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 09-20-2004, 07:40 PM
Member
 
Last photo:
Join Date: Apr 2004
Location: Georgia
Posts: 3,573
Wiki Edits: 0

Thanks: 10
Thanked 57 Times in 36 Posts
24 hours after you sprayed the primer. That should be a safe bet!
That would be worse case scenario.
(at 70 degrees or higher)
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 09-20-2004, 07:45 PM
Member
 
Join Date: Feb 2003
Location: Weatherford Tx
Age: 73
Posts: 168
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Barry
I did not get your post until i had already posted the last Question. The filler was sprayed in 100 plus weather.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 09-20-2004, 07:53 PM
Member
 
Last photo:
Join Date: Apr 2004
Location: Georgia
Posts: 3,573
Wiki Edits: 0

Thanks: 10
Thanked 57 Times in 36 Posts
Thats cooking!
You should be in good shape now!
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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




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



All times are GMT -6. The time now is 12:29 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.