How to repaint my front bumper? Attn: Guitarman
06-27-04, 12:34 PM
#1
How to repaint my front bumper? Attn: Guitarman
Hi, I will be repainting my front bumper this coming up weekend due to some scratches/chips/some modifications I will be doing. Now Im good at the mechanical sense of working on cars, but when it comes to bodywork, Im not bad, but too experienced. I am looking for some advice on how to prepare/paint my front bumper cover the same color. I have a great Craftsman 6HP/30Gal air compressor, a decent gravity feed HVLP gun with 1.4mm and 2.0mm tip. The paint I bought was DuPont Nason Fulthane 2K Urethane Single Stage Black Onyx, along with Dupont Nason Medium Reducer and Dupont Catalyst. I need help with a few things: 1.) Since Im respraying the bumper with the same color, how much should I sand the bumper? And what grits should I use? 2.) AFter sanding, should I apply a sealer first, or maybe even a primer, or should I just spray on the paint? 3.) How long after spraying the paint will I have to wait before mounting it?
I would greatly appreciate any help, and I know Guitarman knows something about this
Thanks alot!
I would greatly appreciate any help, and I know Guitarman knows something about this
Thanks alot!
Last edited by /Aerostar\; 06-27-04 at 12:35 PM.
06-27-04, 10:34 PM
#2
You will have to check your compressor, although that's a decent size unit, HVLP guns demand at least 11 cfm to deliver the volume demands of that gun. I still paint with an old siphon feed gun and 5 HP compressor, but I know what's involved for HVLP.
That said, you might still get by even if it isn't quite capable of delivering 11cfm+ for just respraying something as ( relatively) small as a bumper. The compressor may have some slight delivery issues though,( may run out of air during a long sweeping spray).
That ( Nason) is decent, mid line paint, I use ChromaBase generally, but there's nothing there that should be a problem for you.
Here's the drill;
If the old paint isn't flaking or severly chipped etc. you can simply degrease it well then wetsand it with 600 grit. You don't need to spray a primer nor sealer unless there's some epoxy patchwork or unless it was previously sprayed with some dissimilar paint, which is very unlikely. If it's old oem paint, you're fine to just scuff and spray.
If it IS chipped or flaking and the plastic bumper shows through anywhere, you will have to use 400 grit on those areas, then feather out with 600 to 800 grit until you can't feel any transition from sanded areas to the good paint, with your fingers. If you can feel it, you will see it (esp. on black).
You'll then have to spray a plastic prep (clear bonding agent) first, prior to basecolor though, that's a must once you sand away the existing paint and hit the urethane bumper plastic. I'm guessing you won't be doing any repair type sanding though, because you would have probably mentioned that.
Old cured enamel paint that is bonded well provides an EXCELLENT base for new paint, that's why primer isn't necessary here. You don't need anything else but to scuff it as mentioned, and then spray your base & clear. Again, you ONLY need the plastic prep if you sand through the existing paint, otherwise you're fine with what you've bought.
Pay special attention to degreasing it. Before you sand it, you should hit it with Comet cleanser, then rinse real well, then use an ammonia based window cleaner, and then even 3M prepsol or 3M wax & grease remover. After you sand it, use the 3M degreaser and then a tack cloth before you spray. There is no overkill with prep and degreasing. You don't want any silicones to be nearby - make sure no one is spraying tire dressing or Armor All in the immediate vicinity when you're about to paint. It can travel over a block through the air and cause fisheyes.
Don't breath that stuff either. There is no OSHA approved respirator for activated clears, they contain isocyanates, real bad stuff. If you don't have a positive flow air system, the best thing to do is run a fan behind you and blow all the spray away from you. I'm not trying to be your mother here, but trust me, it can give you asthma after 1 spray, or worse. Hold your breath, spray a pass or two, then run away if you must, just don't breath the clearcoat.
Let the bumper dry at least 24 hours before you handle it, or try to put it on.
Let me know if I can help further, best of luck!
That said, you might still get by even if it isn't quite capable of delivering 11cfm+ for just respraying something as ( relatively) small as a bumper. The compressor may have some slight delivery issues though,( may run out of air during a long sweeping spray).
That ( Nason) is decent, mid line paint, I use ChromaBase generally, but there's nothing there that should be a problem for you.
Here's the drill;
If the old paint isn't flaking or severly chipped etc. you can simply degrease it well then wetsand it with 600 grit. You don't need to spray a primer nor sealer unless there's some epoxy patchwork or unless it was previously sprayed with some dissimilar paint, which is very unlikely. If it's old oem paint, you're fine to just scuff and spray.
If it IS chipped or flaking and the plastic bumper shows through anywhere, you will have to use 400 grit on those areas, then feather out with 600 to 800 grit until you can't feel any transition from sanded areas to the good paint, with your fingers. If you can feel it, you will see it (esp. on black).
You'll then have to spray a plastic prep (clear bonding agent) first, prior to basecolor though, that's a must once you sand away the existing paint and hit the urethane bumper plastic. I'm guessing you won't be doing any repair type sanding though, because you would have probably mentioned that.
Old cured enamel paint that is bonded well provides an EXCELLENT base for new paint, that's why primer isn't necessary here. You don't need anything else but to scuff it as mentioned, and then spray your base & clear. Again, you ONLY need the plastic prep if you sand through the existing paint, otherwise you're fine with what you've bought.
Pay special attention to degreasing it. Before you sand it, you should hit it with Comet cleanser, then rinse real well, then use an ammonia based window cleaner, and then even 3M prepsol or 3M wax & grease remover. After you sand it, use the 3M degreaser and then a tack cloth before you spray. There is no overkill with prep and degreasing. You don't want any silicones to be nearby - make sure no one is spraying tire dressing or Armor All in the immediate vicinity when you're about to paint. It can travel over a block through the air and cause fisheyes.
Don't breath that stuff either. There is no OSHA approved respirator for activated clears, they contain isocyanates, real bad stuff. If you don't have a positive flow air system, the best thing to do is run a fan behind you and blow all the spray away from you. I'm not trying to be your mother here, but trust me, it can give you asthma after 1 spray, or worse. Hold your breath, spray a pass or two, then run away if you must, just don't breath the clearcoat.
Let the bumper dry at least 24 hours before you handle it, or try to put it on.
Let me know if I can help further, best of luck!
Last edited by Guitarman; 06-28-04 at 09:50 AM.
06-27-04, 10:40 PM
#3
Remember, you scuff the old paint ONLY to dull it completely, there should be NO shiny areas anywhere when you're done with the 600 grit. Once you achieve that, stop sanding.
Some use 400, but you'll be better off , with less chance of seeing sanding scratches under the new paint with 600, and you'll have no bonding issues if you thouroughly de-gloss it.
Some use 400, but you'll be better off , with less chance of seeing sanding scratches under the new paint with 600, and you'll have no bonding issues if you thouroughly de-gloss it.
06-28-04, 03:35 PM
#4
Alright, sounds great, thanks alot. One more thing, this is a single stage paint, so I thought it didnt need clearcoat? Or will I need to go back to the paint store and buy some Nason clearcoat. ALso, just to double check, this is what I will be doing:
Remove bumper, clean with Comet, rinse, Windex, Prepsol, wetsand with 3M 600 grit, Prepsol, Tack cloth, spray base, spray clear (?), wait a day, install.
Alsoo, after I spray it nd wait a day, should I wetsand with 2000 grit oor use some rubbing compound or something?
Thanks alot
PS. I wont be able to see the sanding marks through the paint left by the 600 grit will I? Just checkin
Remove bumper, clean with Comet, rinse, Windex, Prepsol, wetsand with 3M 600 grit, Prepsol, Tack cloth, spray base, spray clear (?), wait a day, install.
Alsoo, after I spray it nd wait a day, should I wetsand with 2000 grit oor use some rubbing compound or something?
Thanks alot
PS. I wont be able to see the sanding marks through the paint left by the 600 grit will I? Just checkin
Last edited by /Aerostar\; 06-28-04 at 04:06 PM.
06-28-04, 04:12 PM
#5
Oops, my bad, I wasn't paying enough attention to what you bought. No problem, you can spray the single stage just the same as base/clear, you can follow the same directions.
It's the same paint really (both are urethane enamels) it's just that clearcoat is unpigmented + the extra step with the base..
After the paint is cured a week or so, if you have orange peel or dirt & debris in it ( you will if you're painting in a garage or driveway) you can block wetsand it with 2000 then compound and polish it out. Let me know what you need in that regard, because I 've done a ton of it and can give you things to read and info if you're hesitant to do it.
The 600 is perfect for what you're doing. If you were sloppy with 400 grit, I'd say you *might* see sanding marks under the paint. You'll be fine, but if it worries you, paint supply shops sell 3M scuff pads designed specifically for scuffing paint prior to topcoating. They are like ScotchBrite pads.They will approximate 600 grit sandpaper.
If you run into any problems PM me and I'll also give you a # you can reach me if you need to get a fast answer to a problem. Cheers.
It's the same paint really (both are urethane enamels) it's just that clearcoat is unpigmented + the extra step with the base..
After the paint is cured a week or so, if you have orange peel or dirt & debris in it ( you will if you're painting in a garage or driveway) you can block wetsand it with 2000 then compound and polish it out. Let me know what you need in that regard, because I 've done a ton of it and can give you things to read and info if you're hesitant to do it.
The 600 is perfect for what you're doing. If you were sloppy with 400 grit, I'd say you *might* see sanding marks under the paint. You'll be fine, but if it worries you, paint supply shops sell 3M scuff pads designed specifically for scuffing paint prior to topcoating. They are like ScotchBrite pads.They will approximate 600 grit sandpaper.
If you run into any problems PM me and I'll also give you a # you can reach me if you need to get a fast answer to a problem. Cheers.
Last edited by Guitarman; 06-28-04 at 04:21 PM.
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06-28-04, 04:18 PM
#8
I never really asked, but I should have;
Have you ever sprayed car paint before?
P.S. Here are the 3M scuff pads;
http://multimedia.mmm.com/mws/mediaw...LLLz0QXOkkkkJ-
Have you ever sprayed car paint before?
P.S. Here are the 3M scuff pads;
http://multimedia.mmm.com/mws/mediaw...LLLz0QXOkkkkJ-
Last edited by Guitarman; 06-28-04 at 04:25 PM.
06-28-04, 06:10 PM
#9
No I have not sprayed car paint before, I am very inexperienced in that. But I will be practicing on some sheet metal before I spray the bumper, and if I dont feel confident about doing it, I will have my dad (a house painter of 30 years with some experience in car painting and HVLP guns) do it. As for the scuff pads, should I get those or the 600 grit I already have? I have no problem in buying those, Im just wondering which is better
06-28-04, 10:09 PM
#10
Honestly, you should be fine with the 600 grit paper, it's not as difficult to scuff up old paint as you might think. Just towel the water off after you sand a bit so you can see what you've done. If it's hazy and dull with no shiny spots, that's what you're after. Then move on down the bumper doing the same thing. You should buy a foam 3M block to give you even pressure, but you can use a sponge behind the paper too, better than your hand because the pressure will be distributed more evenly than with your fingers. For scuffing an entire bumper you can get away with just your hand behind it, but if you were wetsanding a scratch or such you'd actually see indents from your fingers when concentrating on a single spot like that. But that doesn't apply the same way for you here.
Use a bucket with some dish soap in it and keep the paper wet, and rub with medium pressure, Just use light pressure on any ridges and don't spend much time on them. The same would apply to a scuff pad-you don't want to cut through the paint where it's thin. You'll see it will scuff pretty fast, with just a pass or 2 on each area.
As for the spraying itself, I think it's good to practice first. Runs will be a problem for a beginner, so here are a couple tips;
Make your first coat a "ghost" coat. That means that you only spray a very thin coat that doesn't have to cover fully. Then let it flash ( means the recommended time on the label between coats) and spray the second coat thin, but try to get opacity, so you can't see any of the scuffed bumper anymore. The 3d coat should do the same. Finally, you can again repeat that step with another thin coat, (depending on how much paint you have) or spray a final "wet" coat that flows out and self levels. This is harder than it sounds because you will at first have to get a feel for just how much paint you can lay on it (especially vertical areas) without getting it to run.
Try that whole approach with a garbage can or old lawn mower first. The important thing is to NOT rush each coat and observe flash times as stated on the paint can. Better to go a bit longer than shorter, time wise.
Make sense?
Use a bucket with some dish soap in it and keep the paper wet, and rub with medium pressure, Just use light pressure on any ridges and don't spend much time on them. The same would apply to a scuff pad-you don't want to cut through the paint where it's thin. You'll see it will scuff pretty fast, with just a pass or 2 on each area.
As for the spraying itself, I think it's good to practice first. Runs will be a problem for a beginner, so here are a couple tips;
Make your first coat a "ghost" coat. That means that you only spray a very thin coat that doesn't have to cover fully. Then let it flash ( means the recommended time on the label between coats) and spray the second coat thin, but try to get opacity, so you can't see any of the scuffed bumper anymore. The 3d coat should do the same. Finally, you can again repeat that step with another thin coat, (depending on how much paint you have) or spray a final "wet" coat that flows out and self levels. This is harder than it sounds because you will at first have to get a feel for just how much paint you can lay on it (especially vertical areas) without getting it to run.
Try that whole approach with a garbage can or old lawn mower first. The important thing is to NOT rush each coat and observe flash times as stated on the paint can. Better to go a bit longer than shorter, time wise.
Make sense?
06-29-04, 03:16 PM
#11
Sounds great, thank you so much for the advice. Ill go to the paint store and autozone, and if they dont have the scuff pads, Ill just use the 600 grit. As for the spraying, that sounds like a great approach and dont worry, Im gonna take my time. I cant wait to do this this weekend
Thanks again G-man
Thanks again G-man
Last edited by /Aerostar\; 06-29-04 at 03:18 PM.
07-10-04, 08:37 AM
#12
Alright, finally my bumper is done. The paint is very nice, the old chipped up bumper really ruins the look of the whole car. After spraying, we (me and my dad) ended up with a whole lot of orange peel 
, but after 2000 grit wetsand, 3M rubbing compound and finesse-it II, she is looking very good. The paint is almost flat, but it has lost some of the gloss. It still looks awesome, and I cant wait to throw on some Klasse next weekend to really shine it up. Thakns alot Guitarman for all your help
, but after 2000 grit wetsand, 3M rubbing compound and finesse-it II, she is looking very good. The paint is almost flat, but it has lost some of the gloss. It still looks awesome, and I cant wait to throw on some Klasse next weekend to really shine it up. Thakns alot Guitarman for all your help
07-10-04, 10:48 AM
#13
Looks really good from here, nice work!
Most people that try that for the first time vow to never go through it again, lol. It sure is labor intensive and attention to small details is imperative.
I'm wondering why you lost some gloss after the wetsanding/buffing...hmmm
How long after you painted it did you wetsand? If you rush it it can "die back" a bit due to the solvents still escaping before full cure. It could also be in need of some high speed rotary finishing to bring it up (gloss) more.
Also, because (unlike with a body shop) the paint wasn't baked to accelerate the cure, you really should wait more than a week to put the Klasse' on it. (30 days is safest). I would anyway, some of the solvents will be off-gassing for a bit yet, and if you lock them in you'll probably see more dulling.
After going through all that why risk it, patience pays. Nice work though, i'm impressed.
Most people that try that for the first time vow to never go through it again, lol. It sure is labor intensive and attention to small details is imperative.
I'm wondering why you lost some gloss after the wetsanding/buffing...hmmm
How long after you painted it did you wetsand? If you rush it it can "die back" a bit due to the solvents still escaping before full cure. It could also be in need of some high speed rotary finishing to bring it up (gloss) more.
Also, because (unlike with a body shop) the paint wasn't baked to accelerate the cure, you really should wait more than a week to put the Klasse' on it. (30 days is safest). I would anyway, some of the solvents will be off-gassing for a bit yet, and if you lock them in you'll probably see more dulling.
After going through all that why risk it, patience pays. Nice work though, i'm impressed.
07-10-04, 12:16 PM
#14
Thank you, it sure was labor intensive, but man it was fun! Seriously, I wouldnt mind doing it again. ANd I waited 48 hours before the initial westand/compounding, and then I waited another 12 hours for the second dose of wetsanding/compound/finesse-it. After looking it at it a little more, its not nearly as dull as I thought it was, it actually looks great. I think one last treatment of Finesse-it II would really help. Also, I guess it would be smart to wait a little longer before klassing it, but Im afriad that by then, the bumper will be chipped again 
Ill snap some more pics once my stupid rechargable batteries for my camera finally recharge!!
Thanks again
Ill snap some more pics once my stupid rechargable batteries for my camera finally recharge!!
Thanks again
