Spray and re-spray...(long one) - 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 07-07-2005, 10:24 AM
VWFan's Avatar
Farfegnugen
 

Last journal entry: logo fun!
Last photo:
Join Date: Sep 2004
Location: Colorado
Age: 38
Posts: 182
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Spray and re-spray...(long one)

I need some advice on a recent paint job I did on a 68 Bug Convertible.... I am using PPG Omni 2 stage acrylic enamel and the gun is a Vaper gravity fed HVLP with a 1.4 tip. The compressor is a 5hp 20gal unit (small, but it works) I am using the recommended 21psi at the gun and I have my wall regulator opened up all the way. I'm spraying in my garage in a make-shift booth. I use two 20" box fans and an oscilating fan, Airflow is not great, but it keeps the air moving fairly well. I am painting the car solid white. Here's the deal...

I started my job by sanding the car down to mostly bare metal and shooting a coat of self etching primer. So far so good...

Then I moved on to 2k high build and shot about 3-4 coats and block sanded the body. I touched up some burn through with some epoxy primer and feather edged. The body work is good and everything seems to be going okay...

I then shot 3 coats of base (white) and 3 coats of clear. When I was finished I had some pretty bad dry spray / overspray / orangepeel, a small flake, a few pieces of dust, a hair, and a bug in my clear coat. I know that this is mostly due to poor gun adjustment. So, I waited overnight, readjusted my gun, and then shot 3 more coats of clear. Still the same orangepeel and dry spray problems... I have since read that if the first coat is rough the rest will be too... So my gun adjustments were probably in vain, but I did get to go through the steps again.

I figured I could wet sand with 1500-2000 and buff out. So, as of now I have sanded the entire car with 1500. This took care of most of the orangpeel, overspray, and dry spray, but the bug, dust, flake, and hair are still there. I also think I may have burned through the clear in some spots (I am not sure how to tell for sure) I am getting white in my sanding water...

With all of the defects I am seriously considering just re-spraying the entire car (I have plenty of materials). I don't think that the paint is nearly as thick as the number of coats I appiled would lead me to believe, but I do not have a mil gauge, so I'm guessing... My plan was to just scuff up the surface with some 400 grit, shoot another two coats of base and 3-4 coats of clear. Will this be sufficient or do I need to take it back down to the primer and start from there? I don't want it falling off in chunks later...

I seem to be having a hard time getting the clear to flow out too. It is MC260 clear / MH168 hardner. I can get it to flow pretty well on a panel, but by the time I get around the car I get dry/overspray. I am thinking of spraying the fenders, hood, and deck lid off of the car to try and keep this from happening. Is this a good idea? I have heard that reducing the clear with thinner to get it to flow is a bad idea, so I would like to stay away from that. Can I use a little more hardner to get it to flow better?

I know there is a lot here, sorry for the long post, but any help will be greatly appreciated...Thank you in advance!!!

    Advertisement

Last edited by VWFan; 07-07-2005 at 11:32 AM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 07-07-2005, 12:08 PM
Member
 
Last photo:
Join Date: Nov 2003
Location: Green Bay, WI
Age: 44
Posts: 2,073
Wiki Edits: 0

Thanks: 0
Thanked 6 Times in 6 Posts
Ohh the fun of painting at home where little dust and bugs like to find your paint job. Paint it early in the morning on a calm day and hose down the area you are spraying in well. Wear a cap or spray sock and hopefully this will prevent you from getting a hair in the paint if it did indead come from you. Sanding with 400 sounds good, you don't have to go down to the primer. Keep drying the panel and looking it over to see when the bad spots are sanded out. Then spray like you normally would. wipe with wax and grease remover tack the surface, spray your base till coverage then after proper flash time spray your clear coats. I don't know what to tell you as far as you getting dry spray. A 1.4 sounds good for clear if using a gravity feed hvlp. Are you sure you are spraying with the proper pressure and technique. Have the fan and material flow on the gun correct, maintaining the proper distance and overlap when spraying. No you should not add more hardener to the paint, you want that to be mixed at the exact ratio the clear recommends. You can add a little slow reducer to help flow better, but don't go overboard. What kind of hardener comes with the clear, I haven't used omni clear for a very long time, but I remember it did seem to flow alright back when I did. Make sure the hardener is for an overall and not a spot panel type hardener. Also work out a pattern around the car when spraying. Everyone is different, but I start with the roof and down the pillars, go to quarter panel over trunk and other quarter panel. Back to the first side and spray door, to other door and finish up with the fenders and hood. Sometimes I may spray farther on the sides before going to the other side if It isn't drying out too fast and am keeping a wet edge. You can usually tell when you sand through the clear to the base, but if you buff the area you thought you went through and you did, you will be able to tell for sure. Also you want to make sure the paint on it has been sitting a while, or else you can have problems painting over clear which isn't fully cured.

Last edited by kenseth17; 07-07-2005 at 12:13 PM.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 07-07-2005, 12:36 PM
VWFan's Avatar
Farfegnugen
 

Last journal entry: logo fun!
Last photo:
Join Date: Sep 2004
Location: Colorado
Age: 38
Posts: 182
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for the input. I have been using a bunny suit and hair net like you wear in the hospital OR, so I think I've got that down pretty well.

The paint has been drying for a few weeks now and I probably will not get to re-spray it for another couple of weeks, so I think I will be okay there.

How would I be able to tell if the hardener is for spot repair or overall? The tech sheet says it is for spot or panel repair. I am using the MH168 slow and I have been painting when it is about 80*-85* outside.

I am sure most of my problems are coming from poor gun adjustment and just plain inexperience. I will keep practicing with my gun adjustment to try and get it to flow out better. I think one of my main questions is this... If my clear is atomizing properly should I be able to make it all the way around the car before the first part I sprayed starts to dry? It seems like most people spray a whole car and don't seem to have the trouble with the dry spray as I did. When I shot the clear the first time I almost could not get the clear to run without really laying it on SLOW and HEAVY. That's why I was thinking of painting the pieces seperately. I can get the clear to lay out just fine when I do the hood, but the overspray when I get to the fender makes the hood look like crap. It's like I'm un-doing what I just did...

Thanks for the suggestions. Anyone else have any other tips?
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 07-07-2005, 01:07 PM
Member
 
Join Date: May 2005
Location: georgia
Posts: 166
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
well im in georgia and man it is hottt here, so ive been using very slow hardener,also you may want to reduce the clear about 5%, with a very slow reducer,i have been using chromaclear reducer,for this.you should have plenty of clear on the car if you clear it twice 3 coats each, so i doubt youve burned through,for the trash and hair, sand it with 800, then you can clear over 800 grit scratches if you dont burn through,also since your painting white i would paint the fenders, hood decklid at one time, then paint the body the next , i try do paint cars in pieces whenever i can, it really makes for a cleaner job and no dry edges , you can take your time with the clear,make sure everything is tacked good as far as the base, it is just so much easier,hope this helps my freind, mike.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 07-07-2005, 01:39 PM
Member
 
Last photo:
Join Date: Nov 2003
Location: Green Bay, WI
Age: 44
Posts: 2,073
Wiki Edits: 0

Thanks: 0
Thanked 6 Times in 6 Posts
I took a peak at the ppg site. The mh168 seems like it should be okay. The 80 degrees is at the top of the temp range for it though. There is one slower hardener very slow mh169. They also make a retarder that can be added up to 5% which will give more flow out time. Maybe try painting when it is a little cooler out with the hardener you have, that might help. But first of all I would try wetsanding and buffing it out and see if you can save it. Maybe you will get lucky and all will look good, or maybe you only will have to repaint a panel or two instead of the whole car again. Yes you should be able to get around the car without dry edges. But you should alternate sides of the vehicle to prevent a panel from sitting too long before getting back to that area with clear on the adjacent panel. I start with the roof. Then the part I did first where it maybe sitting a few minutes before i get back to that point is a small area, the pillars.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 07-07-2005, 04:15 PM
Shakey's Avatar
Member
 
Last photo:
Join Date: May 2005
Location: Seattle
Posts: 37
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Sounds like we have very similar problems on our Bugs. My worst spot is where the fender meets the body and makes a inside corner, I got some dry spray.

Like you I am a newbie, and was never completely confident I was getting the gun adjusted right. But beyond the gun, and my inexperience, I think the biggest problems were that I didn't have real great airflow, so the overspray just kind of hung there. Also I wish I had more lights to put in the booth. I never felt like I could really see what was happening as good as I should.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 07-07-2005, 05:09 PM
VWFan's Avatar
Farfegnugen
 

Last journal entry: logo fun!
Last photo:
Join Date: Sep 2004
Location: Colorado
Age: 38
Posts: 182
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Yeah, the area where the fenders meet the body is where I had the worst dry spray also. I hope that with some more practice I can get the clear to flow better and not have to play the cut and buff game... I also think I am going to paint the fenders, hood, and deck lid seperate from the car to help keep this from happening as much the next time around. I think the bottom line is that I just need more practice, after all this is an art.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 07-07-2005, 05:10 PM
Member
 
Last photo:
Join Date: Nov 2003
Location: Green Bay, WI
Age: 44
Posts: 2,073
Wiki Edits: 0

Thanks: 0
Thanked 6 Times in 6 Posts
Yep, I posted that many times. You can never have enough lights and need pretty good ventilation. I have painted a bunch over the years, but at home it is still somewhat of a challenge even though I've done quite a few garage paint jobs. I don't have great lighting in my garage and am somewhat guess painting. I broke down a month ago and bought a bigger fan and will get to try it out soon. Will be painting a cavalier in the near future. Finishing up the bodywork right now. I painted one vw bug convertable at one of my jobs and remember it was a little different. Kinda like painting a ball, with all the curved panels. Plus painting white is also more of a challenge because it is harder to see how it is laying out then darker colors.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 03-17-2011, 03:38 PM
mean s15
 
Last photo:
Join Date: Mar 2011
Location: geneva ny 14456
Age: 34
Posts: 53
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
orange peel and overspray

I would get a bigger air compressor. Run it @ 40 / 50 psi to solve your Orange peel problem, check the recommended viscosity for the clear. Your gun is starving for air and not atomizing properly. Maybe that will help you out.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 03-17-2011, 10:17 PM
milo's Avatar
point on positive
 
Last photo:
Join Date: Sep 2003
Location: milogarage Calif.
Age: 58
Posts: 1,675
Wiki Edits: 0

Thanks: 3
Thanked 5 Times in 3 Posts
Quote:
Originally Posted by VWFan
I have heard that reducing the clear with thinner to get it to flow is a bad idea, so I would like to stay away from that. Can I use a little more hardner to get it to flow better?
Of course you wouldn't tune or adjust the clear viscosity with any lacquer type thinner you have laying around..you would use the correct REDUCER (MR or DT) ,, and you would check it somewhere other than the project your wanting to look good like on whats called a test panel/card.

The thing nobody talks about here is viscosity. Many take for granted the new guys know how to adjust the viscosity of primers,bases and clear and overlook a detailed explanation and simply rant about tech sheets. Well the tech sheet is good to get it close but are often "padded info" and tuning material viscosity isn't found on a tech sheet it is learned by trial and error. This trial and error can be at the mix bench way before the redo trial.
Here's a link that just might help..
http://www.a2zautoforums.com/showthread.php?t=2795

Best advice is gonna be to unmask the car...wash with soap and water .. dry with clean dry filtered air..remask and dust on more base and reclear with everything at the right viscosity and the room/booth at 70 degrees..

Being able to exhaust that cloud of over spray before it lands on your project is important especially on the last wet coat of clear..

*Do a search on viscosity before you blame any equipment

This may not help you because there are so many comments (guesses) coming in here all at once but it might help the new guy who is reading up before jumping in on his car...

Last edited by milo; 03-17-2011 at 10:41 PM. Reason: did a search for the type of reducer for that clear
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



All times are GMT -6. The time now is 01:58 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.