A strange situation? - 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 07-03-2007, 10:04 AM
Member
 
Last photo:
Join Date: Aug 2005
Location: UK
Age: 48
Posts: 109
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
A strange situation?

Hi guys

I was blocking (with a 3M marine board & p120 paper)some panels last night. They had 2 coats of epoxy, 4 coats of 2k high build & a dark contrasting coat of wet on wet.

I blocked all of the wet on wet off & alot of the 2k high build, when a few areas of the epoxy was showing through I stopped.

When I re primed the panels there was a line of small dents right down the middle on both doors where maybe a rub strip had been removed?

Why, when all the dark guide coat had gone from the top of the grey primer were the dents not revealed? I just don't understand it.

Your thoughts please guys.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 07-03-2007, 07:07 PM
Bee4Me's Avatar
Problem Child,Hard Case
 

Last journal entry: Strangest job I've ever done
Last photo:
Join Date: Jan 2005
Location: ARK.
Age: 57
Posts: 1,773
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Panel flex.
On the truck doors I've been working on,They had a body moulding which I removed and had a nice "ditch" where they were.After striping,epoxy and polypriming I guide coated first and X sanded and I still have low spots that the "guide" showed was gone until I reguided and used VERY light pressure to sand with,Reprimed with poly,reguided and had areas that were low still. I used glaze putty on them,reprimed and solved the problem.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 07-04-2007, 01:53 AM
Member
 
Last photo:
Join Date: Aug 2005
Location: UK
Age: 48
Posts: 109
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Sounds like I would have been better off skim coating the whole door in 2k stopper, then priming.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 07-04-2007, 06:54 AM
cboy's Avatar
Member
 

Last journal entry: Finished
Last photo:
Join Date: Jan 2004
Location: Atwater, CA
Age: 69
Posts: 3,918
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 4 Posts
Bee4Me provides a working solution...but still doesn't explain your initial question of why these imperfections did not show up in the guide coat. The only thing I can come up with is that the 120 grit was so coarse it took everything down so quickly you couldn't see the low spots. Hardly seems possible you wouldn't have seen something.

Also, what is "2K stopper"?
__________________
Always learning...and sharing what I've learned. The Scratch-Built Hot Rod.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 07-04-2007, 08:18 AM
302 Z28's Avatar  
Last photo:
Join Date: May 2003
Location: North Texas
Posts: 10,840
Wiki Edits: 0

Thanks: 1
Thanked 86 Times in 73 Posts
Panel deflection, your pressing so hard you are distorting the panel and the low spots are not being hit.

Vince
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 07-04-2007, 09:51 AM
cboy's Avatar
Member
 

Last journal entry: Finished
Last photo:
Join Date: Jan 2004
Location: Atwater, CA
Age: 69
Posts: 3,918
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 4 Posts
Quote:
Originally Posted by 302 Z28
Panel deflection, your pressing so hard you are distorting the panel and the low spots are not being hit.
Vince,

Wouldn't the problem be that the low spots ARE being hit...and hit too hard? I would think if the low spots were not being hit that they would show up like a sore thumb in the guide coat.
__________________
Always learning...and sharing what I've learned. The Scratch-Built Hot Rod.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 07-04-2007, 12:23 PM
Member
 
Last photo:
Join Date: Aug 2005
Location: UK
Age: 48
Posts: 109
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
mm, point taken. I thought using P120 would find all the low spots. It's the first time I have used the 3m marine board, I thought bit would be the mutts nuts since it is so large.

2k stopper by the way is a very fine bondo.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 07-05-2007, 05:04 AM
Member
 
Last photo:
Join Date: Jan 2005
Location:
Posts: 3,707
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
Also make sure your sanding boards and blocks are perfectly straight, it is very common to find plastic, rubber, and wooden handle type boards/blocks that are warped even when new. You can't make a panel straight with a warped block/board.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 07-05-2007, 08:08 AM
MARTINSR's Avatar
Brian Martin,Freelance adviser
 
Last photo:
Join Date: Jun 2004
Location: San francisco bay area
Age: 55
Posts: 13,276
Wiki Edits: 0

Thanks: 1,420
Thanked 1,219 Times in 1,075 Posts
Quote:
Originally Posted by Steve UK
Hi guys

They had 2 coats of epoxy, 4 coats of 2k high build & a dark contrasting coat of wet on wet.
What did you mean by the "wet on wet" comment? A guide coat should be a "misting" of color. If you applied a wet coat of another color, yeah it "should" show up, but it may require harder sanding and it the panel flexed as mentioned.

Also, "wet on wet", did that mean that it was applied while the urethane primer (I assume your 2K is urethane) was wet? If that is the case, the urethane probably sucked up some of your "guide coat" so when you sanded the you didn't sand the guide coat off, properly because it was part of the urethane coat as well.

A guide coat should be very lightly "Misted" so it sands off easy. You don't "try" to sand it off, you BLOCK, and if it IS sanded off, cool, if it isn't, then it did it's job. A lot of guys TRY to sand the guide coat off and do all kinds of strange stuff with pressure or sanding direction. You need to hold the block FLAT on the surface and just sand.

Brian
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 07-05-2007, 11:09 AM
RAYzr's Avatar
Registered User
 

Last journal entry: RAYzr
Last photo:
Join Date: Jul 2007
Location: Richland, WA
Age: 62
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I love the "boat board" as we call it and we use it all of the time...one of the problems that occcasionally comes up, though is the board is actually too long cuz the surface has slight countour or diagonally sanding with it actually "saws off material where it shouldn't and creates countour where it shouldn't" and causes the very situation you describe....the rule here is, if
you're having this trouble, down size the board to say 24" composit board and equally diagonally sand ( say 10 strokes one way, 10 the other) and see if this helps with the problem...just a humble idea...
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 07-05-2007, 01:11 PM
Member
 
Last photo:
Join Date: Aug 2005
Location: UK
Age: 48
Posts: 109
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
All good info guys, thanx

My primer is acrylic 2k - 5:1:10% aplied with a sata NR95 with a 1.9 tip set, does that make a difference?

Wet on wet was my contrasting color primer guide coat, mixed very thin.

I have never used a "boat board" before & now you mention it I was hitting the highs of the frame pressings really early on. The board was two thirds the length of my doors so maybe it was too long for that job. I have blocked for 15yrs using an 18" block for my maximum length, only a few weeks ago did I invest in my new longer blocks. I do have a 24" so I will try that.

I so need to get this project spot on it's at a show in September!
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 07-05-2007, 02:22 PM
MARTINSR's Avatar
Brian Martin,Freelance adviser
 
Last photo:
Join Date: Jun 2004
Location: San francisco bay area
Age: 55
Posts: 13,276
Wiki Edits: 0

Thanks: 1,420
Thanked 1,219 Times in 1,075 Posts
Quote:
Originally Posted by Steve UK

Wet on wet was my contrasting color primer guide coat, mixed very thin.
But was the urethane primer WET when you applied the over reduced "primer guide coat?"

Brian
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 07-05-2007, 09:30 PM
crashtech's Avatar
Technician
 
Last wiki edit: Epoxy primer
Join Date: May 2005
Location: Idaho
Posts: 701
Wiki Edits: 17

Thanks: 0
Thanked 0 Times in 0 Posts
A lot of doors have blobs of sound deadening material between the intrusion beam and the skin. They will firm up the metal where the are sitting and cause uneven material removal.

One solution is to begin blocking with the coarsest grit possible and very light pressure, moving up in grit as you go. Very time consuming but nearly the only way I have found to achieve straightness on certain vehicles.

I recall Honda hoods (bonnets ) to be notorious for this problem.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 07-06-2007, 12:10 AM
Member
 
Last photo:
Join Date: Aug 2005
Location: UK
Age: 48
Posts: 109
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The 2k primer had flashed off but was not dry when the wet on wet was applied.

I think I will re block with P80 next, lightly!
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:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Strange Pro Race Steel Brakes? VolvoGuy Suspension - Brakes - Steering 4 06-29-2007 11:10 AM
Strange vacuum problem JohnyR17 Engine 8 03-16-2006 04:05 PM
Strange welding situation I found willys36@aol.com General Rodding Tech 27 09-10-2005 07:14 PM
Strange noise in Powerglide woody51 Transmission - Rearend 2 08-20-2005 02:22 PM
Strange vs Motive Rear Gears, also which ratio: DTL504 Engine 4 04-28-2005 01:36 PM


All times are GMT -6. The time now is 01:12 PM.


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.