I'm nearing the point at which I'm considering painting all the underside cowl/inside/truck space, and was wondering what is the best way to prep those areas prior to painting. There are lots of nooks and crannies that don't lend themselves to scuffing or fine sanding. I will be doing a section at a time during swap-out of parts, like the front suspension and steering. I will be making a color change (from green to silver), so good adhesion is imperative. Is it perhaps better to spray some type of primer to avoid any bleed through of the original color? I will of course talk with my paint dealer, but thought I'd ask those who have already been through this. Any suggestions are appreciated.

Andy

I don't see any away around not at least scuffing it down.

You have to scuff/sand all the large areas, PERIOD.

Spray all the tight areas and seam sealer areas with brake cleaner and quickly blow dry with compressed air. Then do it again and let the brake cleaner sit a few seconds before drying with the compressed air.

The brake cleaner will remove oil and will also soften the paint and seam sealer a bit, which increases adhesion in these areas.

Been doing it this way for years.

Ed

Hey Evil one,

I was wondering that same thing last night. I didn't want to scrape out all of the seam sealer and was wondering what sort of latitude I have. I'll try what you mention and hit it with paint.

If I'm using self etch primer for the clean bare floorpan, will it stick to the softened seam sealer? should I hit it all with a high build primer before paint?

Sorry for the hijack, jack.

QUOTE (Evill Ed @ Jan 10 2005, 01:56 PM)

You have to scuff/sand all the large areas, PERIOD. Spray all the tight areas and seam sealer areas with brake cleaner and quickly blow dry with compressed air. Then do it again and let the brake cleaner sit a few seconds before drying with the compressed air. The brake cleaner will remove oil and will also soften the paint and seam sealer a bit, which increases adhesion in these areas. Been doing it this way for years. Ed

Ed,

That exact though crossed my mind too. I use brake clean for grease/oil removal before painting all sorts of stuff, so it was a natural thought for prepping these incidental areas as well.

Any thoughts on priming before a color change? Any recommendations on a good seam sealer?

Andy

3M sanding sponges are great for trunks and door jambs. You can get them at Ace. Scotchbrite pads work well too. Brake cleaner would work but tends to evaporate too fast. Best is degreaser made for auto paint prep, such as Grow Industries cleaner/degreaser. 3M makes seam sealers that are brush on or use caulking gun. The brush-on will be closer to the factory look. For color change all you need is a sealer coat, or you can use epoxy primer as a sealer. You can paint your top coats over the sealer or epoxy right after flashing. You might check to see if there's a Finishmaster in your area.

I thought about Scotchbrite. Sanding sponges are a good idea.

I have a couple of spots where I did some welding, and now I'm down to bare metal there. Think it'd be ok to spot in those areas with rattle can red oxide primer from FLAPS, or do I need something different/better?

Thanks,

Andy

If you use an epoxy as a sealer you won't need to spot prime the welds. I tend to avoid the rattle can primers from FLAPS and hardware stores as most are lacquer-based and are incompatible with the urethanes I use. Not to say you can't use them if that's what you have, but just make sure they are completely dry before putting on your top coats. If there's any solvent trapped it will cause your sealer or paint to wrinkle and lift up.

QUOTE (swood @ Jan 10 2005, 02:14 PM)

Hey Evil one, I was wondering that same thing last night. I didn't want to scrape out all of the seam sealer and was wondering what sort of latitude I have. I'll try what you mention and hit it with paint. If I'm using self etch primer for the clean bare floorpan, will it stick to the softened seam sealer? should I hit it all with a high build primer before paint? Sorry for the hijack, jack.

Stevo, the self etch is fine for the bare metal. Clean it good with a scotchbrite pad and degrease prior to priming it to remove any oxidation first. Older German steel rusts quickly when left exposed.

Also, always leave the factory seam sealer if it is in good condition. It is far better than what you can apply yourself.

Ed

QUOTE (andys @ Jan 10 2005, 02:20 PM)

QUOTE (Evill Ed @ Jan 10 2005, 01:56 PM) You have to scuff/sand all the large areas, PERIOD. Spray all the tight areas and seam sealer areas with brake cleaner and quickly blow dry with compressed air. Then do it again and let the brake cleaner sit a few seconds before drying with the compressed air. The brake cleaner will remove oil and will also soften the paint and seam sealer a bit, which increases adhesion in these areas. Been doing it this way for years. Ed Ed, That exact though crossed my mind too. I use brake clean for grease/oil removal before painting all sorts of stuff, so it was a natural thought for prepping these incidental areas as well. Any thoughts on priming before a color change? Any recommendations on a good seam sealer? Andy

Andy, not sure what you mean about priming before a color change. Do you mean priming to protect bodywork until you repaint?

If you are doing a color change, you should strip the old paint off. Then use an epoxy base primer. You will use a build primer over this to blosk out and level the surfaces. Finally, you will spray a sealer prior to top coating. The epoxy primers can be reduced to be used as sealers. It comes in several colors, chose one that is close to your top coat to get faster coverage. i.e. If your final color is red, use the red primer.

I like 3M brushable seam sealer a lot. SEM and Tremco are good too, they are all pretty much the same.

You can get good quality spray can primers from autobody supply shops. SEM make one.

Ed

QUOTE (Evill Ed @ Jan 10 2005, 05:39 PM)

[QUOTE=andys,Jan 10 2005, 02:20 PM] Andy, not sure what you mean about priming before a color change. Do you mean priming to protect bodywork until you repaint? If you are doing a color change, you should strip the old paint off. Then use an epoxy base primer. You will use a build primer over this to blosk out and level the surfaces. Finally, you will spray a sealer prior to top coating. The epoxy primers can be reduced to be used as sealers. It comes in several colors, chose one that is close to your top coat to get faster coverage. i.e. If your final color is red, use the red primer. I like 3M brushable seam sealer a lot. SEM and Tremco are good too, they are all pretty much the same. You can get good quality spray can primers from autobody supply shops. SEM make one. Ed

Ed,

The advice I got was that if the paint you want to cover is in good condition, then you don't need to strip it down to metal (this is not for a show quality paint job). That said, I do want to make a color change, and recognize that a minor chip could reveal that deep green color I would be covering in silver. Though my original question was aimed at most of the seldom seen areas, I would imagine what to prime/seal/paint would apply regardless of where it is. As I see it, it perhaps comes down to a decision of whether to completely strip the car, or paint over the original color with the proper sealer/primer? There will of course be localized areas where I will have bare metal from repairs, etc. Hope this clarifies my questions.

Thanks,

Andy

I worked in a body shop for 2yrs and oil was our enemy. Even over spray from wd40 woudl fisheye the paint really bad. And brake fluid will soak into the paint and even remove it. Im not saying it is a bad idea it is just one we never used at Phillips Auto Body.

QUOTE (andys @ Jan 10 2005, 08:32 PM)

[QUOTE=Evill Ed,Jan 10 2005, 05:39 PM] [QUOTE=andys,Jan 10 2005, 02:20 PM] Andy, not sure what you mean about priming before a color change. Do you mean priming to protect bodywork until you repaint? If you are doing a color change, you should strip the old paint off. Then use an epoxy base primer. You will use a build primer over this to blosk out and level the surfaces. Finally, you will spray a sealer prior to top coating. The epoxy primers can be reduced to be used as sealers. It comes in several colors, chose one that is close to your top coat to get faster coverage. i.e. If your final color is red, use the red primer. I like 3M brushable seam sealer a lot. SEM and Tremco are good too, they are all pretty much the same. You can get good quality spray can primers from autobody supply shops. SEM make one. Ed [/QUOTE] Ed, The advice I got was that if the paint you want to cover is in good condition, then you don't need to strip it down to metal (this is not for a show quality paint job). That said, I do want to make a color change, and recognize that a minor chip could reveal that deep green color I would be covering in silver. Though my original question was aimed at most of the seldom seen areas, I would imagine what to prime/seal/paint would apply regardless of where it is. As I see it, it perhaps comes down to a decision of whether to completely strip the car, or paint over the original color with the proper sealer/primer? There will of course be localized areas where I will have bare metal from repairs, etc. Hope this clarifies my questions. Thanks, Andy

Andy, if your car has original paint, you can clean it well and sand it with 220 grit paper. Then you can prime over it for your new top coat.

If you car has been repainted already, I would strip it to bare metal on the outside panels.

Ed