My roof is bare metal and has surface rust on it.

What grit paper should I use to prep it for primer. Thanks, Cal

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TC Member # 1308

my trailer queen (http://www.chevelles.com/showroom/trailerqueeny.jpg)
future racer (http://www.chevelles.com/showroom/austin.jpg)
justins 67 (http://www.chevelles.com/showroom/67sideveiw.jpg)
cals caminos web site (http://72sselcamino1.tripod.com/calscaminos/)

[This message has been edited by 72sselcamino (edited 08-19-2002).]

The finer the grit the more rust you will remove on a SMOOTH surface. So 180 or 220 will do the job. After you have sanded the rust off the 180 would be best for the primer.
Now, it is very hard to give advice as to that to do without seeing it. Ones man's "surface rust" is another man's "pitted rust".

I think you may need a metal "conditioner" like DuPonts "Metal prep" to get rid of the rust for good.

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1965 Buick Gran Sport Convertible
1965 Buick Skylark H/T
"Fan of most anything that moves human beings"

I might need to tell you it's going to have a vinyl top, if that matters at all as for as pitting would be concerned. But before I started this thread, I used some 120 on an electric palm sander and found NO PITTING that I could see so far. Let's see if these pic's are good enough to help you see.

roof 1 (http://www.chevelles.com/showroom/temproof1.jpg)
roof 2 (http://www.chevelles.com/showroom/temproof2.jpg)

Now for the inside. It's hard to see, but out in the middle of the roof, the gray primered section, is also getting some very light surface rust. inside (http://www.chevelles.com/showroom/temproof4.jpg). I assume they used the wrong kind of primer, and I've waited to long to get it painted. Any tips what to do in there.

I'm also concered about the pinch weld where they put a new roof on the car. Where the 2 surfaces meet also has surface rust. What should I do to try and get in between them. I thought about wire brushing it the best I could and maybe using the brush that comes with pinch weld primer to try and get up in there as far as I can.

The guy at the paint store gave me this primer (http://www.chevelles.com/showroom/tempprimer.jpg) to use on the roof. Would this be correct for the job.

I don't know why he didn't primer the roof too. He did the rest of the car.

As alway's, thanks for any help. Cal

[This message has been edited by 72sselcamino (edited 08-19-2002).]

Anyone

Based on your pictures I would use 80 grit on flat surfaces. Sand, sand, sand, until ALL brown gone. Use a DA orbital sander. Be careful not to get too hot, use fresh paper, and change often. You are not trying to polish metal. Agree with MARTINSR, metal prep will be required. Follow instructions on product carefully. On pinch welds and in cavities, there are some fibre disc's from 3M that work very well. Also a broken 1/8' drill bit or a pall like drill attachment bit can work very well in small cavities. I have not used the SEM product, but their materials are good. Remember that self etch primers are conversion coatings, they are intended to improve adhesion, and corrosion resistance, they are NOT filler/sanding primers. When we use them, we spray a very light coat, still transparent, but fully covered, then one coat epoxy, then a two part sanding primer. As it will have a vinyl top, small pits and surface imperfections are not a bug deal, however, the more rust you clean, the less you will have to worry about later. Always paint under vinyl top, as primers are porous, and top will retain moisture. Vinyl tops installed over primed surfaces create an environment for future RUST. If you like I will get 3M #s on discs. Remember all safety precautions regarding eyes, breathing etc. Karl

OOPS< after 80 grit switch to 180 as MARTINSR said. Karl

Since you are installing a vinyl top, you could go the POR-15 route. www.por15.com (http://www.por15.com)

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1967 Chevelle SS (Butternut Yellow!)

<BLOCKQUOTE>quote:</font><HR>Originally posted by Frank G:
Since you are installing a vinyl top, you could go the POR-15 route.<HR></BLOCKQUOTE>

I think that's an excellent idea.


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Bob Von Kaenel
70 SS 54k orig miles
My car. (http://www.chevelles.com/showroom/barista70front.jpg)
The red interior. (http://www.chevelles.com/showroom/barista70interior2.jpg)
The engine. (http://www.chevelles.com/showroom/barista70engine.jpg)
Hood trim. (http://www.chevelles.com/showroom/baristasgirls.jpg)

I like that idea too. http://www.chevelles.com/forum/biggrin.gif I have to admit, I know nothing about POR 15. I wonder if there would be any issue's with the vinyl top glue adhearing.

Anyone see any other problem's that mught accour. Let's here what you guy's think. Thanks, Cal

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TC Member # 1308

my trailer queen (http://www.chevelles.com/showroom/trailerqueeny.jpg)
future racer (http://www.chevelles.com/showroom/austin.jpg)
justins 67 (http://www.chevelles.com/showroom/67sideveiw.jpg)
cals caminos web site (http://72sselcamino1.tripod.com/calscaminos/)

You may or may not know my opinion about the "magic potions" out there for rust, but I ALWAYS treat the top that is getting a vinyl top EXACTLY the same as if it wasn't getting one. Etch, urethane primer, base color and clear.

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1965 Buick Gran Sport Convertible
1965 Buick Skylark H/T
"Fan of most anything that moves human beings"

Agree with MARTINSR, POR15 needs an additional binder coat to be compatible with conventional topcoats. You would end up tapering POR15 down into 1/4s, and then have to use conversion product underneath 1/4 paint. Or sharp edge at clip/mldg area @ 1/4. GOOD prep and cleaning will be adequate if rust is as appears, and you have stated. Part #s for 3M cleaning products. 1460 50 grit, 1407 36 grit, 1408 24 grit, these are ROLOC discs, that thread on to 3" pad, to be used with drill. The fibre disc # is 07470, use like you would a wire wheel. Works great on spot welds, and uneven surfaces. I am not against use of POR 15, have plenty of it on my Elky, it does have it's place, but it is NOT a cure all for everything. Karl

Thanks guy's. Cal