Guys who know how to do bodywork / paint - advice needed

[96C220]

Okay I'm in the process of reparing collision damage to my 2000 Mercedes c230 kompressor that my lil brother was kind enough to wreck for me.

Here is the question I have. I replaced the hood, with a new aftermarket piece, which came in what appears to be black primer. I also had to do some work on the front bumper cover, and I primed that myself and wetsanded with 400 grit 3M imperial wet or dry sandpaper.

The bumper feels smoother than the hood at this point. I plan on doing everything but the final paint work (which will go to a body shop). Should I prime and wetsand the hood to make it even with the bumper, or is that primer applied to the part already sufficient and ready to paint?

Here is a pic of what it looks like - I do notice that every touch leaves fingerprint and hand oil impressions on it.



Thanks in advance,

George

[donbryce]

Hi. From what you have posted, at this point, I'd select the bodyshop and discuss with them what paint system they will use. You should save some money doing the priming/sanding prep yourself, but you should use a product compatable with theirs. Some color coats will specify a 'value shade' for the final coat of underlying primer, so it's possible to use a 'high build' primer under that to perfect the surface first. This is usually an epoxy product mixed per the manufacturers directions, and could be a brand different from the value shade primer used by the body shop, but it would be best to get their input first. Otherwise, later, they may blame you for flaws in the final paint topcoat that show up long after the car has left their spray booth.
Also, you'll need a good prep/cleaner to thoroughly remove hand print oil and dirt before you start sanding, or you'll work the oil into the surface where it will ultimately bleed up through the primer and mess up the color/clear coat.

[96C220]

Yeah I've used the PPG High Build Primer on the front bumper, and wetsanded it down to 400. I was told you can go to 600, and have the paint still get a good grip, but I was kind of worried because of the added adhesion needed with the urethane front bumper cover. I know they add adhesion promoter and flex agents to it, but should I go to 600, or just leave it at 400?

As far as I can tell MB used Glasurit sp? paint on the car, as that is what the color code specifies, but can this color be obtained via other manufacturers? Also, should I trust the paint code, or should I have them computer color match and custom mix. I don't have to worry about any paint blending (as far as spraying) because all the panels that are going to be refinished end in body lines (front bumper cover, hood, and the molding under the headlight).

Chances are I will probably remove the hood and bumper cover from the car, after showing them the complete car, and just bring them those panels. I don't want them painted on the car (overspray is all but inevitable), and there is no point in paying them to remove / reinstall them. I spent about two hours adjusting the hood to get the gaps right, so im going to take an awl and mark the bolt outlines with a score, so I'm 90% there when I get the parts back.

As far as cleaning oils etc... I'm using 91% Isopropyl Alcohol on clean cotton waffle cloths. Is this sufficient. This is what I have used while detailing, and havent had a problem removing old products (which are probably worse petroleum based compounds than hand oils), but should I go to something stronger here?

I was actually contemplating spraying the finish coats here, and making an improvised spray booth in the garage with a couple fans, and a bunch of 7-9 mil plastic. I have a respirator setup, and have access to a suitable compressor, but I'm worried that there will be too many variables (temperature, humidity, as well as possibly contaminants in the air supply from the compressor - i know they use large filters on their compressed air, and a pressure regulator). So I've kind of shyed away from that idea.

Thanks for all the advice, and any additional pointers would be greatly appreciated.

If you are interested, all the pictures, from start, to teardown, and rebuild are here PICTURES

Thanks again and take care,

George

[Ferdman]

George, I'd forget about attempting the finish coat at home in a makeshift spray booth. The body shop booths, in addition to their dustless, humidity-controlled environment, also have heating capability to cure the paint. Glasurit and Siekens are unavailable. Many bodyshops use Dupont paints ... my brother-in-law sells Dupont paints to shops in Tennessee and Kentucky.

It appears that you still have some fine tuning to do on the bumper alignment, as on the passenger side it projects too far back into the wheel opening. Nice job repairing the bumper gouge.

As suggested already select the bodyshop that will do the finish coat and discuss in detail the prep work and materials that you will use. You can bet that the shop will point the finger at you if there are any complaints about the finished product. For instance the bumper repair may appear perfect now, but the finish coat will expose any minor flaw.

[96C220]

Originally Posted by Ferdman

It appears that you still have some fine tuning to do on the bumper alignment, as on the passenger side it projects too far back into the wheel opening. Nice job repairing the bumper gouge.

.

The inner fender liner isnt even attached to the bumper and is loose (pop rivet clips and screws on the bottom) its just swinging loose, and in fact is in front of the bumper instead of tucking into the edge, that is giving you the impression of the missalignment ... I just hung the bumper to get a rough idea, and have a place to wet sand it off the ground. The inner fender liner is sitting behind the bumper... Since I am going to have to take all of this stuff off again, to get it painted, and in the bumpers case to reattach those chrome moldings under the headlights, no need to sit there and line everything up perfectly, since it all has to come apart again.

I agree that the makeshift booth isn't the best idea, Once I get the lights installed and I have the car driveable, I will take it to a few good shops and talk to them about it, and see what they have to say, and then get the parts painted.

Take care,

George

[donbryce]

I have to admire your degree of perseverence here. I hope you have enlisted your errant sibling's aid to do all that sanding! I went through all the pictures and you are 99% on track here.

I've used a Dupont product called Wash N Wipe for cleaning and prepping prior to sanding and during priming stages, with great success. It may no longer be available, but I'm certain there is a 'new and improved' product now. Other manufacturers have similar products, and are well worth the investment. Your sanding to 400 will do nicely for the high build, IMO.

One small detail is that if you bring the hood in separate, they may paint it standing up rather than flat as it will be in final position. If they do, depending on the type of paint, especially metallics, you may see a slight pattern or color difference where the top of the fenders meet the edge of the hood.

Bodyshops don't really take very long to mask and cover the car to avoid overspray, since they don't want to have to clean it off either. Ask the foreman about the 'extra' cost to do this, and if any savings would be offset by the hassle of handling the separate parts before, during and after the paintwork. A top-notch job will require several stages of sanding and polishing of the topcoat with a power buffer to remove orange peel, and that is much easier when the parts are on the car. Then, you need to consider damage while you transport them home and re-install.
Just a few thoughts...