Redo Clear Coat Instead of Re-Paint? - PeachParts Mercedes-Benz Forum

shertex · #1 04-07-2012, 02:36 PM

Several years ago, when the clear coat on the hood of my 92 300D was badly delaminating, I had it repainted. Now the trunk is badly delaminating. Moreover, there's a car I've thought about buying that is delaminating all over. My question: if the paint itself is in good condition in a situation like this, can I simply strip and reapply the clear coat? Or does tend to be a throwing-good-money-after-bad approach?

Thanks.

toomany MBZ · #2 04-07-2012, 03:12 PM

I have to wonder what the paint will look like after you sand off the clear coat.

Dubyagee · #3 04-07-2012, 03:45 PM

If your going to go through all the prep to clear it might as well base coat it first.

mach4 · #4 04-07-2012, 04:23 PM

If it's delaminating, that means it's no longer sticking. Anything you put over the top of something that's delaminating will just continue to delaminate taking the new finish with it. As was said, if you're going to prep it, might as well take it down to good substrate and lay a color coat down. If you keep it the same color, any little masking errors will not visible.

Renntag · #5 04-07-2012, 05:12 PM

There is really no clear answer here (pun intended).

Assumptions made above, although good advice are leaving out important info.

1. you have no idea why clear peeled.
2. will a new clear stick for the duration of your ownership? No idea without trying.
3. is the current base coat worth keeping? Again no idea.
4. Will any modern clear be compatible with existing base? Not sure.

Bottom line here is that any shop giving a guarantee of their work is going to want to remove bad coatings, apply a sealer coat, apply a totally new finish.

Note that there are many good quality single stage paints on the market today that will provide a good finish. Some colours are only possible in 2 stages (base/clear).

Either way, trying a short cut is certain worth a shot, but why not try on one panel and let it eat for a couple years. Best way to tell. The other thought is just to repaint the whole deal. Maaco offers great deals for the budget conscious. If you want the best for your special Benz, then maybe 3-5000$ worth of top notch refinishing is within your budget? I wouldnt want to pay more than 5-800$ for the repainting portion of a make over for my old car.

If you have something that is going to hold value above 10K into the future, then sure, drop money on a spendy repaint. If not, even a low end repaint is going to help preserve the car into the future.

Note to anyone considering a repaint. It is best to remove everything from the outside of the car, trim, lights, emblems, everything. In some cases removing glass panels to paint in the window opening helps a great deal.

I am preparing to remove my sunroof panel, repaint and rebuild the roof panel with new seals. (300TD).

barry123400 · #6 04-07-2012, 05:19 PM

Not a good ideal in my opinion for almost endless reasons.

Renntag · #7 04-07-2012, 05:35 PM

Quote:

Originally Posted by barry123400

Not a good ideal in my opinion for almost endless reasons.

What is an "Ideal" ?

alabbasi · #8 04-07-2012, 06:00 PM

Once the clear coat peels, you'll need to sand it down completely and repaint the base and clear. You can sand down good clear and shoot over it as long as you don't go into the base but judging by your description, this is not an option.

cjbrown · #9 04-13-2012, 02:56 PM

Quote:

Originally Posted by Renntag

>snip
1. you have no idea why clear peeled.
2. will a new clear stick for the duration of your ownership? No idea without trying.
3. is the current base coat worth keeping? Again no idea.
4. Will any modern clear be compatible with existing base? Not sure.

Bottom line here is that any shop giving a guarantee of their work is going to want to remove bad coatings, apply a sealer coat, apply a totally new finish.

Note that there are many good quality single stage paints on the market today that will provide a good finish. Some colours are only possible in 2 stages (base/clear).

>snip

About the only voice of reason here...

I mean no disrespect, but if you don't have experience with automotive painting it's best to listen (read) instead of post.

By the numbers above:

Clearcoats breakdown and peel off. The basecoat will not survive prep for re-shooting clear.
No, it won't. And you can't prep properly for it.
No. Easy to re-shoot and then clearcoat.
redundant.

Single stage paint will only work for a solid color. All metallics need a clearcoat. It's all just so easy to do that it's not worth screwing around with, just re-shoot it. For a solid color, if you can get a high quality acrylic enamel with a hardener like Centari, will give an oem quality appearance. Again, will not work for metallics.

If you don't sand thru the base layer and in particular, the primer layers, then you don't need a sealer, just shoot the base color on and clear coat it. If you do sand thru in a couple of places they can be spot-primed and sealed. A rattle can of sealer will work for this without buying a whole can of paint. They are all waterbased now.

I just went thru this on a 1996 Toyota we bought for my son to drive. I've been doing automotive painting as a hobby for almost 40 years. It had peeling clearcoat on the hood and roof, now looks like a new car.

If the substrate is good it can be sanded down with 150 to remove the peeling clear, then overall with 500 grit to prep for re-shoot.

Dupont's Nason line is inexpensive and can be color matched to an existing finish. Only a very competent paint jobber can do this. Drop the fuel door off to them and they'll color match it. Nason in general matches very poorly to an oem finish, worse on an aged one. So a color match is essential. The refinish I did cannot be descerned from the original - it matches perfectly, even were it was blended on the quarter pillar. A shoot-able quart and clear with reducers and activators will run about $150. Chroma System will run three to four times that - just for the paint. Nason has a 8-10 year lifespan, longer if kept garaged.

If you have painting experience it can be done in a home garage. If not, you need the services of a competent autobody paint shop.

bmwpowere36m3 · #10 04-13-2012, 10:43 PM

I'll say it's possible, it's how they blend panels after body work. However it really depends on the condition of the paint... are you doing the work yourself? Really you can't sand with anything coarser than 400 because it will put in deep scratches into the base coat that the clear coat will amplify after its laid down.

You could sand with 400 to get the majority of the clear off, then 600 (and then 800 if it's a metallic base color).

cjbrown · #11 04-13-2012, 11:34 PM

Quote:

Originally Posted by bmwpowere36m3

I'll say it's possible, it's how they blend panels after body work. However it really depends on the condition of the paint... are you doing the work yourself? Really you can't sand with anything coarser than 400 because it will put in deep scratches into the base coat that the clear coat will amplify after its laid down.

You could sand with 400 to get the majority of the clear off, then 600 (and then 800 if it's a metallic base color).

Where did you get this? It is NOT how they "blend panels". This is exactly what I was talking about in my last post - I can tell by the way you explain things that you are not a painter.

First of all, a 'blended panel' blends into something that's already finished - the clearcoat is in good condition. You scuff it so the new clearcoat has bite, or 'key'. A scotchbrite pad works well for this. If you're blending base coat into it then it goes over what's there and everything gets cleared over. Wet sand, buff/polish.

As soon as you hit a metallic finish it's toast. You cannot sand a metallic finish, it ruins it. It has to be laid down fresh and clearcoated.

400 grit will NOT remove flaking clearcoat. And just how exactly will you know when to quit sanding the old clear before you get into the base color? Are you kidding me? Plus, if it's flaking in one area then it will continue to do so, so why would you paint over it? Will clear coating over old flaking clear coat stop it from flaking, bubbling, and peeling? I didn't think so.

It's also very rare to patch within a single panel, rather an entire panel is refinished to it's edge or to a seam.

500grit finish sanding cannot be discerned under a final finish once it's wet-sanded and polished. The finish coats fill in fine scratches, they don't "amplify" them. Yes, they are easier to see because of the gloss, but they aren't amplified. Some buffing compounds are 'body shop safe' just for this reason, so you can buff primer to a sheen to see imperfections. Then it's lightly sanded to key the next coat(s).

Show quality finishes since 1975.

shertex · #12 04-14-2012, 06:49 AM

Thanks for all the input, everyone. Whatever I do, I'd need to have someone else do it....I'm a complete amateur. Seems to make sense just to live with it as long is I care to and then get it completely and professionally repainted.

t walgamuth · #13 04-14-2012, 07:12 AM

Its one of those things that sound very plausible but in the end I believe cjbrown is giving you the straight scoop.

IE my wife's PT cruiser has pretty decent paint but the clear is getting dull. I asked my favorite paint shop about scuffing it and just redoing the clear. He said he'd do all new base coat and clear coat for the same price.

bmwpowere36m3 · #14 04-14-2012, 04:14 PM

Quote:

Originally Posted by cjbrown

Where did you get this? It is NOT how they "blend panels". This is exactly what I was talking about in my last post - I can tell by the way you explain things that you are not a painter.

First of all, a 'blended panel' blends into something that's already finished - the clearcoat is in good condition. You scuff it so the new clearcoat has bite, or 'key'. A scotchbrite pad works well for this. If you're blending base coat into it then it goes over what's there and everything gets cleared over. Wet sand, buff/polish.

As soon as you hit a metallic finish it's toast. You cannot sand a metallic finish, it ruins it. It has to be laid down fresh and clearcoated.

400 grit will NOT remove flaking clearcoat. And just how exactly will you know when to quit sanding the old clear before you get into the base color? Are you kidding me? Plus, if it's flaking in one area then it will continue to do so, so why would you paint over it? Will clear coating over old flaking clear coat stop it from flaking, bubbling, and peeling? I didn't think so.

It's also very rare to patch within a single panel, rather an entire panel is refinished to it's edge or to a seam.

500grit finish sanding cannot be discerned under a final finish once it's wet-sanded and polished. The finish coats fill in fine scratches, they don't "amplify" them. Yes, they are easier to see because of the gloss, but they aren't amplified. Some buffing compounds are 'body shop safe' just for this reason, so you can buff primer to a sheen to see imperfections. Then it's lightly sanded to key the next coat(s).

Show quality finishes since 1975.

Look we can all play armchair quarter back and yes I have a lot of painting experience under my belt (father is a mechanic and body man by trade). Without seeing the paint its hard to really give advise.

Your right in that base coats typically don't get sanded, they are sprayed, flash over and then cleared. However, they can be sanded and yes sanding metallics will "ruin" the finish. I used to finish wet-sanding with 600 before apply base and it was fine on non-metallics, but on metallics it does show up if you look closely under bright lights at least that has been my experience using mostly Spies Hecker products.

I highly disagree if you meant that wet-sanding prior to base coat with only 500 grit will not show through the finish... That is exactly the opposite what I've experienced, was taught and other painters have told me... base coats and clear coats WILL amplify any imperfections in the "base" layer.

Blending panels, again your right in that you sand the entire "finished" panel, then blend the color and finally clear everything. I personally wouldn't use a scotchbrite pad for the sanding (red or gray) the finished panel, but at a minimum wet sand with 1000 grit paper. But hey if that works for you. Typically I leave the scotchbrite pads for bumpers, trim, roughing e-coats on new panels and very intricately shaped/tight panels (B surfaces, those that aren't visible from the outside or are hidden from view).

I had an older 300E (smoke gray, a metallic gold of sorts) that the clear was pealing only on the roof some and the rest of the paintwork was in decent condition. A proper job would have been sanding it down smooth, applying primer any bare spots, wet-sanding, base and then clear. However if I did the roof, I would have been tempted to do the whole car... I just wanted a quick job that would look all right, hold up and then I could sell the car. I sanded and smoothed the clear as much as I could and shot it with clear. Now the car is with a new owner and the roof still looks decent and the clear is not compromised.