? on sanding - 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 06-20-2010, 08:00 AM
Registered User
 
Join Date: Sep 2009
Location: whitmore lake mi
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
? on sanding

i sanded my 7 mustang down to bare metal with 80 grit, do i resand it down with a different grit before i spray epoxy on it then the primer, thanks for any input

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-20-2010, 09:05 AM
roger1's Avatar
 
Last photo:
Join Date: Feb 2004
Location: San Angelo,TX
Age: 59
Posts: 1,098
Wiki Edits: 0

Thanks: 12
Thanked 5 Times in 5 Posts
Quote:
Originally Posted by pappastang
i sanded my 7 mustang down to bare metal with 80 grit, do i resand it down with a different grit before i spray epoxy on it then the primer, thanks for any input
80 grit will be fine.
You can wash it down with water and dawn dish soap. Dry it , then wipe it down with a waterborne w&g remover, let dry and your ready to spray. Be sure to use an automotive grade w&g remover or you can have problems.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-20-2010, 10:10 AM
MARTINSR's Avatar
Brian Martin,Freelance adviser
 
Last photo:
Join Date: Jun 2004
Location: San francisco bay area
Age: 55
Posts: 13,118
Wiki Edits: 0

Thanks: 1,292
Thanked 1,138 Times in 1,008 Posts
HOLD ON HERE, we are talking bare metal ! DO NOT wash with water, DO NOT wash with waterborne wax and grease!

If it is bare metal use a solvent borne wax and grease and honestly, if you just removed everything with 80 grit, what is there to contaminate?

We are a little late with this, but next time, DO NOT STRIP THE ENTIRE CAR! Strip a panel or two and then get it into primer.

I would still recommend this now, if you can't sand the whole car with 120 or 180 right now to remove any flash rust, I would be sanding a few panels SPOTLESSLY CLEAN then get them into primer. Then move on to the next panels.

But to strip the whole car with 80 and a day or more later prime it? You are going to be priming over flash rust!

I seriously doubt you have all the paint off, I doubt you have done the "detail" work around body lines and edges and the like.

Go over every panel with 120 or 180 to finish the job and clean up any flash rust and paint or primer left from the 80 grit and get it into epoxy primer. If you do this over the entire car, you will have flash rust again! So do a panel or two and get it into primer. Then move onto the next few panels after your epoxy has kicked.

Brian
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-20-2010, 10:14 AM
roger1's Avatar
 
Last photo:
Join Date: Feb 2004
Location: San Angelo,TX
Age: 59
Posts: 1,098
Wiki Edits: 0

Thanks: 12
Thanked 5 Times in 5 Posts
Really Brian?

I have never had any problem with flash rust if water or waterborne is wiped off immediately.

Quote:
Originally Posted by MARTINSR
and honestly, if you just removed everything with 80 grit, what is there to contaminate?
Oil from the D/A would be the biggest thing. There could be other contaminates as well from the sanding debris.
Quote:
Originally Posted by MARTINSR
But to strip the whole car with 80 and a day or more later prime it? You are going to be priming over flash rust!
Primering over minor flash rust is done all the time. I've never seen it cause problems. Remember back in the days when we were supposed to use metal conditioner? It was impossible to use that stuff and not have flash rust before primering.

Also, here's a quote from Barry's "The Perfect Paint Job":
"All bare metals and aluminum should have 80 grit DA scratches.
Bare metal is always best cleaned with #700-1 Waterborne Wax and Grease Remover then let it set 30-60 minutes before applying the epoxy
!"

Last edited by roger1; 06-20-2010 at 10:53 AM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-20-2010, 11:05 AM
MARTINSR's Avatar
Brian Martin,Freelance adviser
 
Last photo:
Join Date: Jun 2004
Location: San francisco bay area
Age: 55
Posts: 13,118
Wiki Edits: 0

Thanks: 1,292
Thanked 1,138 Times in 1,008 Posts
Quote:
Originally Posted by roger1
Really Brian?

I have never had any problem with flash rust if water or waterborne is wiped off immediately.

Oil from the D/A would be the biggest thing. There could be other contaminates as well from the sanding debris.
Primering over minor flash rust is done all the time. I've never seen it cause problems. Remember back in the days when we were supposed to use metal conditioner? It was impossible to use that stuff and not have flash rust before primering.

Also, here's a quote from Barry's "The Perfect Paint Job":
"All bare metals and aluminum should have 80 grit DA scratches.
Bare metal is always best cleaned with #700-1 Waterborne Wax and Grease Remover then let it set 30-60 minutes before applying the epoxy
!"
What exactly "Minor flash rust" means is up to interpretation! What one may see as "minor" another would see was RUSTED and must be removed.

As far as the 80 grit scratches, I have to disagree. We are talking BARE METAL here, it isn't going to have TRUE 80 grit scratches anyway, unless a grinder is used the 80 grit scratchs left from your typical paper aren't going to be "80 grit" scratches like those 80 grit scratches left in filler or something.

And epoxy adheres so well, 180 or 120 is PLENTY in my opinion.

But here lies the problem. The 80 grit isn't going to get every bit of the primer and rust off unless you work very hard, possibly not at all no matter how hard you work in some areas. It is scratching "around" stuff. While the finer paper is going to REMOVED all the little specs of everything.

If you want to have an 80 grit scratch, then sand it all real well with the 180 and then go back over with 80. But I feel that is an overkill personally.

Personally, seeing a newbe strip a car with a sander or grinder spells disaster in my experiance. I am trying to come down to a more "controled" condition for the poster. Striping each panel carefully with 120-180 and getting them in epoxy while the metal is clean is more "Likely" going to produce a good job than saying "priming over flash rust is ok" and he primes the whole car that has been sitting in bare metal for three weeks. Or a car that has taken him three or four weeks to strip (like my bathroom remodel) and has a nice coat of rust.

On the waterborne wax and grease on bare metal, yeah, I guess I am old school and hearing "water" on bare metal gives me the creeps. But I guess it is ok if Barry says so.

Brian
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-20-2010, 11:21 AM
TucsonJay's Avatar
Registered User
 
Last photo:
Join Date: Feb 2010
Location: Tucson, Arizona
Posts: 802
Wiki Edits: 0

Thanks: 0
Thanked 96 Times in 75 Posts
What you see after metal prep is not rust, (iron oxide)... it is "iron phosphate", which will cause no problem.

I would not tempt fate with water on bare metal. If you get away with it, great! ...but if you don't....
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-20-2010, 11:30 AM
roger1's Avatar
 
Last photo:
Join Date: Feb 2004
Location: San Angelo,TX
Age: 59
Posts: 1,098
Wiki Edits: 0

Thanks: 12
Thanked 5 Times in 5 Posts
Quote:
Originally Posted by MARTINSR
And epoxy adheres so well, 180 or 120 is PLENTY in my opinion.
But here lies the problem. The 80 grit isn't going to get every bit of the primer and rust off unless you work very hard, possibly not at all no matter how hard you work in some areas. It is scratching "around" stuff. While the finer paper is going to REMOVED all the little specs of everything.
If you want to have an 80 grit scratch, then sand it all real well with the 180 and then go back over with 80. But I feel that is an overkill personally.
Personally, seeing a newbe strip a car with a sander or grinder spells disaster in my experiance. I am trying to come down to a more "controled" condition for the poster. Striping each panel carefully with 120-180 and getting them in epoxy while the metal is clean is more "Likely" going to produce a good job than saying "priming over flash rust is ok" and he primes the whole car that has been sitting in bare metal for three weeks. Or a car that has taken him three or four weeks to strip (like my bathroom remodel) and has a nice coat of rust.
Brian
I understand what you are saying. A person just has to use logic here depending on shop conditions as far as humidity and like you say, time, and assess whether flash rust is a problem or not. I don't have a problem with it here in San Angelo, TX. There are certainly some advantages to primering the whole car at once too. Especially since you can follow up with a high-build primer (filler too if necessary) without sanding before the re-coat window has passed. If you do one panel at a time, you are probably going to pass the re-coat time and have to sand and re-coat the entire car in epoxy before moving on. That's a whole extra step and extra cost in primer.
I agree. Epoxy adheres well to metal sanded in finer grits. Heck, it even adheres pretty well to unsanded metal.
However, since I use SPI products, I will use Barry's recommended procedures for my stuff. I'll make sure the metal is clean with whatever it takes but go back over it with 80 grit. That last part doesn't take that much extra time to do.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-20-2010, 11:37 AM
roger1's Avatar
 
Last photo:
Join Date: Feb 2004
Location: San Angelo,TX
Age: 59
Posts: 1,098
Wiki Edits: 0

Thanks: 12
Thanked 5 Times in 5 Posts
Quote:
Originally Posted by TucsonJay
What you see after metal prep is not rust, (iron oxide)... it is "iron phosphate", which will cause no problem.

I would not tempt fate with water on bare metal. If you get away with it, great! ...but if you don't....
I hope you don't use metal prep with epoxy. That's not a good combo.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 06-20-2010, 11:42 AM
shine's Avatar
SPI Thug
 

Last journal entry: some progress
Last photo:
Join Date: Sep 2004
Location: bluff dale texas
Posts: 2,672
Wiki Edits: 0

Thanks: 0
Thanked 193 Times in 155 Posts
most flash rust is from iron deposits in the water. i wash every car with dawn soap and water. it is the only way to get one clean after blasting. epoxy over mild flash is no problem. scuff it with red scotchbrite and apply 2 coats and your good to go.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 06-20-2010, 11:55 AM
MARTINSR's Avatar
Brian Martin,Freelance adviser
 
Last photo:
Join Date: Jun 2004
Location: San francisco bay area
Age: 55
Posts: 13,118
Wiki Edits: 0

Thanks: 1,292
Thanked 1,138 Times in 1,008 Posts
Quote:
Originally Posted by roger1
There are certainly some advantages to primering the whole car at once too. Especially since you can follow up with a high-build primer (filler too if necessary) without sanding before the re-coat window has passed. If you do one panel at a time, you are probably going to pass the re-coat time and have to sand and re-coat the entire car in epoxy before moving on.
OH GOD YES I am with you there! But if you are doing it at home, it sometimes is a whole different ball game. This is why I recommend it to home newbes. It is up for them to make a call, but if they are aware, it can save them.

Quote:
Originally Posted by roger1
However, since I use SPI products, I will use Barry's recommended procedures for my stuff. I'll make sure the metal is clean with whatever it takes but go back over it with 80 grit. That last part doesn't take that much extra time to do.
Go with the manufacturers recommendations is what I aways say!

Brian
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 06-20-2010, 12:06 PM
Member
 
Last photo:
Join Date: Apr 2004
Location: Georgia
Posts: 3,578
Wiki Edits: 0

Thanks: 10
Thanked 61 Times in 39 Posts
Quote:
Originally Posted by MARTINSR
OH GOD YES I am with you there!


Go with the manufacturers recommendations is what I aways say!

Brian
========================================
Thank you!!!!!!!!

There are 100's of ways to make an epoxy, there are a 100 ways to make a wax and grease remover.

My tech sheet applies to my stuff only and PPG, Duponts tech sheets applies to theirs only.

Do not use one tech sheet for another product, period.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 06-20-2010, 12:15 PM
MARTINSR's Avatar
Brian Martin,Freelance adviser
 
Last photo:
Join Date: Jun 2004
Location: San francisco bay area
Age: 55
Posts: 13,118
Wiki Edits: 0

Thanks: 1,292
Thanked 1,138 Times in 1,008 Posts
You just can't go wrong listening to the people who sell and back the product!

First off, even if it goes against what you think, like my thinking the 80 grit is an overkill. 80 grit as Barry says is CERTAINLY not going to hurt anything. It WILL provide a great surface for the primer. Following his recommendations for the product he sells is always going to be a good way.

Brian
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 06-20-2010, 04:17 PM
Registered User
 
Join Date: Sep 2009
Location: whitmore lake mi
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
i do have all the paint off,and its been at least 3 to 4 weeks and no flash rust i will scuff it up and vac the car, after the w@g remover, ill use a tac rag . is there a solvent that i should wipe the car down before i put the epoxy on. if i run into any problems, i will do a panel at a time. thank you all for your answers
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 06-20-2010, 04:51 PM
roger1's Avatar
 
Last photo:
Join Date: Feb 2004
Location: San Angelo,TX
Age: 59
Posts: 1,098
Wiki Edits: 0

Thanks: 12
Thanked 5 Times in 5 Posts
Quote:
Originally Posted by pappastang
is there a solvent that i should wipe the car down before i put the epoxy on.
Gosh, will all that's been said here, I'm surprised to see you ask this. Go by the P sheet for the particular epoxy you are using. I doubt it will say to use anything besides w&g remover.

Many paint jobs have been ruined by wiping down with lacquer thinner used as a w&g remover before epoxy. Epoxys in general won't cure properly in the presence of acids.

Also, save the tack rags for later. No need for it here. I don't know for sure but I think it can cause problems too.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 06-21-2010, 05:53 PM
Registered User
 
Join Date: Sep 2009
Location: whitmore lake mi
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
i thank you again
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Block sanding help with pics holy85 Body - Exterior 9 08-07-2009 10:10 AM
sanding scratches showing esahlin Body - Exterior 10 07-29-2009 12:42 PM
Interesting test on sanding base coat paint (against the data sheets recommendation) MARTINSR Body - Exterior 208 03-22-2007 10:52 PM
Sanding is the art pepi Body - Exterior 3 08-02-2006 10:40 PM
Color sanding and Buffing questions. Z-Money Pit Body - Exterior 1 05-30-2005 09:41 PM


All times are GMT -6. The time now is 07:20 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.