Im sure this question has been asked before but I have had no luck in searching. I am going to be doing a color change on a honda Civic that is factory white. I am thinking about going to do a dark Blue. I am starting to sand the car and wanted to know how far down I need to take it. Any help would be great as im new to the painting world thanks.
Prep for Paint
- Thread starter Cmoreth
- Start date
T
TAZ
Guest
Hello,
If the paint is in good condition, you don't have to take it down at all. Just sand it good with approx a 320 grit and you'll be good to go.
If you have a few bad spots, just 180 these, and primer them. Then resand these spots with 320.
If the paint is in good condition, you don't have to take it down at all. Just sand it good with approx a 320 grit and you'll be good to go.
If you have a few bad spots, just 180 these, and primer them. Then resand these spots with 320.
T
TAZ
Guest
If you can sand a complete paint job off of a car and just go to the primer without leaving any of the paint, and not go through to the metal (or plastic), you are GOOD!
It's very hard to sand through a paint job to the primer without hitting the metal also. So what you end up with is spots where there are paint, primer, and then metal spots. You 'may' need to primer the complete car, then block it out. A lot of variables come into play though.
What the car was sanded with? How thick the paint job was?
If you feel the car is straight enough, then you might get away with just sealing and painting the car.
It's very hard to sand through a paint job to the primer without hitting the metal also. So what you end up with is spots where there are paint, primer, and then metal spots. You 'may' need to primer the complete car, then block it out. A lot of variables come into play though.
What the car was sanded with? How thick the paint job was?
If you feel the car is straight enough, then you might get away with just sealing and painting the car.
here are the links to the pics of the vehicle im working on and what i've done sofar
http://i948.photobucket.com/albums/ad321/ChadMoreth/IMG_7771.jpg
http://i948.photobucket.com/albums/ad321/ChadMoreth/IMG_7769.jpg
http://i948.photobucket.com/albums/ad321/ChadMoreth/IMG_7771.jpg
http://i948.photobucket.com/albums/ad321/ChadMoreth/IMG_7769.jpg
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T
TAZ
Guest
Looks like you have your self a little project going on there! :yesnod:
Since you are so close to the metal anyway, I would suggest just finishing off and stripping it. You'll be glad you did.
I can tell in the pics that if you painted over what you have now, it would be wavy and lumpy. And if you primed it and blocked it, you'd have a lot of work a head of you and still might not get it straight
Once you strip it, you'll have a clean slate to work from.
You can do any of the bodywork. Then prime it.
I would suggest using a 8" buffer type machine (electric), and set it up to accept 8" 80 grit paper. Once you strip it, DA it with 180, then prime with a good epoxy type primer (2 part primer)
So the job is not so overwhelming to, you can do a couple panels at a time.
Since you are so close to the metal anyway, I would suggest just finishing off and stripping it. You'll be glad you did.
I can tell in the pics that if you painted over what you have now, it would be wavy and lumpy. And if you primed it and blocked it, you'd have a lot of work a head of you and still might not get it straight
Once you strip it, you'll have a clean slate to work from.
You can do any of the bodywork. Then prime it.
I would suggest using a 8" buffer type machine (electric), and set it up to accept 8" 80 grit paper. Once you strip it, DA it with 180, then prime with a good epoxy type primer (2 part primer)
So the job is not so overwhelming to, you can do a couple panels at a time.
T
TAZ
Guest
Don't know if this would be any encouragement for you, but here is a car I did about 8 months ago. One of the roughest 'newer' cars I've worked on.
Stripped it, bodyworked it (inc welding the side molding holes), primed it, then painted it.
Stripped it, bodyworked it (inc welding the side molding holes), primed it, then painted it.
T
TAZ
Guest
Yea, I think that will work out best for you. You're so close to stripping it anyway, you might as well do it. You'll be glad you did in the long run
:bigokay:
:bigokay:
T
TAZ
Guest
We welded up the holes, then we ground it smooth, added a little Duraglass to each hole, then skim coated it with bondo.
Then we primed, blocked and painted
Then we primed, blocked and painted
Kong
New member
Prep is everything. No paint job can ever come out better than the prep that proceeded it. On a re-do, and particularly when you are doing a drastic color change, it is essential that you get a strong ground coat that is one consistent color before you begin laying down your basecoat, artwork (if any) and finally your clear. In the prep process for a re-do you need to sand off everything that stands any chance of falling off (failing) all by itself. So if the earlier paint peeled, was chipped, crinkled, or got bashed in a parking lot you need to sand it off to bare metal; but if its just faded or you just dislike the color about all you may need to do is sand it to break the gloss and paint. How far you go depends on the initial condition of the paint, the worse it is the more of it you take off. Rarely is it really necessary to go all the way to bare metal, though on a personal note I normally do - but I only do motorcycles, so its not that big a deal.
OK, now to the meat. Let me give you a quick review of how to do prep from the metal on up so you understand what materials are used, what they are for, and when they are applied.
First there is your metal. If you've got dents or other problems fix them first, get all of your welding and grinding done. You can use coarse sanding paper to clean the metal, 80 grit will be just fine and you don't have to worry about the deep metal scratches at this time. After the metal has been sanded it needs to be cleaned, use a commercial wax and degreaser, its cheap.
The first thing you shoot on the metal is Epoxy primer. The purpose of the epoxy is to seal the metal; epoxy is waterproof and is perfect for the job. Epoxy also sticks very well to metal and most things stick very well to epoxy. So you start by sealing your metal with the epoxy, 2 medium coats will suffice. Note that for the most part Epoxy primers are non-sandable. Of course you can sand them, I only mean that they were not meant to be sanded and most of them don't sand well at all anyway.
Next you need to start the work of making the panel straight (no hills or valleys) and flat (smooth). You will do this by block sanding material that was meant to be sanded, using the longest blocks you can for each section of each panel. So on top of the epoxy (read the tech sheets for your time windows for recoating of the epoxy and if out of the window scuff the epoxy with a 3M red scuff pad) you need to spray several coats (3 will do nicely) of a high build sandable primer. This stuff, which is often called "2k" (meaning 2 Komponent) is put on the surface to fill minuscule lows and sanding scratches. When you spray this stuff on I want you to let it dry between coats - dry, not tack - in fact I want you to let it set and dry twice as long as you think it should. -- Quick side note -- the 2k primer is the most important strata in the paint job, you have to get this stage right or the entire paint job will either fail or look like hell.
So you shoot 3 coats of 2k primer and then a guide coat and you get started with your first block sanding. On guide coats, for those who haven't used them, they are your best friend. Here's what you do. Shoot your3 coats (or 4 if you like) of 2k and then when the last coat is dry get a can of the cheapest rattle-can primer you can find of a distinctly contrasting color. Stand back about a foot and a half and just dust on an extremely light coat from the spray can; all you are wanting to do is dust on a coat you can sort of see through but that covers the entire surface. Now let is set over night, or better yet, out in the sun for a day. Let it dry - let me say that again - let it dry.
The next thing you need to do is the meat of the matter. Using blocks start sanding the guide coat off. At this point you should be up to sandpaper in the 240p moving up to about 400p grit. All you want to do is remove the guide coat by sanding and the moment its completely gone quit sanding. It is key to quit when you're done. I have seen many a new painter sand the guide coat off and get it perfect, and then screw it up by standing there and keep right on sanding. Quit when you're done, not later. Now when you sand this two things will happen. One is you will sand through to bare metal in some places and in others you won't be able to remove the guide coat because its in low spots. Good, now you know the bare metal spots are high spots and the low spots are the places where the rattle can paint can't be sanded off when block sanding. Take a hammer and lightly tap down the highs and using filler fill the lows. Note, you never want to use filler over about an eighth of an inch thick. If you have to knock metal down and fill lows that's fine, do it, and then repeat your 2k spraying, to include a new guide coat, and do it again. Repeat until perfect. Normally this will take you two, or even possibly three applications of your 2k and of course block sanding.
When you've finally got it straight and flat there will be several strata of materials exposed; there may be more bare metal, there may be epoxy primer exposed, there may be several different layers of 2k exposed (personally I like to use different colors of 2k if more than one application is required just to keep myself mindful of what my sanding is doing).
Final coat: once its straight and flat you need to seal it. You do that with the same epoxy you used as your initial primer, but this time you thin it down a little bit so it lays down a lot better. Thin it with acetone, I personally reduce about 10%, but I know guys who will go as far as 25%. Once that sealer goes on you are on the clock and need to stay within the time windows recommended by the paint manufacturer's Tech Sheets. However, if you need to just go ahead and shoot the sealer (2 medium coats), which will protect the underling surface more or less indefinitely, and if you have to come back days or months later to finsh it all you have to do is scuff it (red pad once again) and re-shoot your sealer.
And that's about it. Metal, epoxy to seal it, 2k to work out the highs and lows, then another layer of epoxy to seal the work and give a consistant color ground coat on which to apply your color. Easy as pie.
On Edit :sillyme:: Always seal your metal and leftover existing finish with epoxy before applying your filler (bondo) material. The filler can be applied over the epoxy or over the 2k. There are some people who will apply filler directly to metal, but you don't want to do that because filler is not waterproof and does not protect the metal, besides, epoxy bonds to metal better than bondo so there is less chance of failure by applying the epoxy first. Hope this helps someone.
Kong
OK, now to the meat. Let me give you a quick review of how to do prep from the metal on up so you understand what materials are used, what they are for, and when they are applied.
First there is your metal. If you've got dents or other problems fix them first, get all of your welding and grinding done. You can use coarse sanding paper to clean the metal, 80 grit will be just fine and you don't have to worry about the deep metal scratches at this time. After the metal has been sanded it needs to be cleaned, use a commercial wax and degreaser, its cheap.
The first thing you shoot on the metal is Epoxy primer. The purpose of the epoxy is to seal the metal; epoxy is waterproof and is perfect for the job. Epoxy also sticks very well to metal and most things stick very well to epoxy. So you start by sealing your metal with the epoxy, 2 medium coats will suffice. Note that for the most part Epoxy primers are non-sandable. Of course you can sand them, I only mean that they were not meant to be sanded and most of them don't sand well at all anyway.
Next you need to start the work of making the panel straight (no hills or valleys) and flat (smooth). You will do this by block sanding material that was meant to be sanded, using the longest blocks you can for each section of each panel. So on top of the epoxy (read the tech sheets for your time windows for recoating of the epoxy and if out of the window scuff the epoxy with a 3M red scuff pad) you need to spray several coats (3 will do nicely) of a high build sandable primer. This stuff, which is often called "2k" (meaning 2 Komponent) is put on the surface to fill minuscule lows and sanding scratches. When you spray this stuff on I want you to let it dry between coats - dry, not tack - in fact I want you to let it set and dry twice as long as you think it should. -- Quick side note -- the 2k primer is the most important strata in the paint job, you have to get this stage right or the entire paint job will either fail or look like hell.
So you shoot 3 coats of 2k primer and then a guide coat and you get started with your first block sanding. On guide coats, for those who haven't used them, they are your best friend. Here's what you do. Shoot your3 coats (or 4 if you like) of 2k and then when the last coat is dry get a can of the cheapest rattle-can primer you can find of a distinctly contrasting color. Stand back about a foot and a half and just dust on an extremely light coat from the spray can; all you are wanting to do is dust on a coat you can sort of see through but that covers the entire surface. Now let is set over night, or better yet, out in the sun for a day. Let it dry - let me say that again - let it dry.
The next thing you need to do is the meat of the matter. Using blocks start sanding the guide coat off. At this point you should be up to sandpaper in the 240p moving up to about 400p grit. All you want to do is remove the guide coat by sanding and the moment its completely gone quit sanding. It is key to quit when you're done. I have seen many a new painter sand the guide coat off and get it perfect, and then screw it up by standing there and keep right on sanding. Quit when you're done, not later. Now when you sand this two things will happen. One is you will sand through to bare metal in some places and in others you won't be able to remove the guide coat because its in low spots. Good, now you know the bare metal spots are high spots and the low spots are the places where the rattle can paint can't be sanded off when block sanding. Take a hammer and lightly tap down the highs and using filler fill the lows. Note, you never want to use filler over about an eighth of an inch thick. If you have to knock metal down and fill lows that's fine, do it, and then repeat your 2k spraying, to include a new guide coat, and do it again. Repeat until perfect. Normally this will take you two, or even possibly three applications of your 2k and of course block sanding.
When you've finally got it straight and flat there will be several strata of materials exposed; there may be more bare metal, there may be epoxy primer exposed, there may be several different layers of 2k exposed (personally I like to use different colors of 2k if more than one application is required just to keep myself mindful of what my sanding is doing).
Final coat: once its straight and flat you need to seal it. You do that with the same epoxy you used as your initial primer, but this time you thin it down a little bit so it lays down a lot better. Thin it with acetone, I personally reduce about 10%, but I know guys who will go as far as 25%. Once that sealer goes on you are on the clock and need to stay within the time windows recommended by the paint manufacturer's Tech Sheets. However, if you need to just go ahead and shoot the sealer (2 medium coats), which will protect the underling surface more or less indefinitely, and if you have to come back days or months later to finsh it all you have to do is scuff it (red pad once again) and re-shoot your sealer.
And that's about it. Metal, epoxy to seal it, 2k to work out the highs and lows, then another layer of epoxy to seal the work and give a consistant color ground coat on which to apply your color. Easy as pie.
On Edit :sillyme:: Always seal your metal and leftover existing finish with epoxy before applying your filler (bondo) material. The filler can be applied over the epoxy or over the 2k. There are some people who will apply filler directly to metal, but you don't want to do that because filler is not waterproof and does not protect the metal, besides, epoxy bonds to metal better than bondo so there is less chance of failure by applying the epoxy first. Hope this helps someone.
Kong
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