ErnestSw

I've been using 3M medium cut compound with my Porter Cable orbital polisher to get rid of some scratches in my paint. Do I have to use a finer compound before I used a glaze or can I put the glaze on over the medium cut?

Herr-Kuhn

I would go down finer. Use a wool pad for the initial cut, then step down to foam...but be careful the foam pad can go through in a hurry. Best to get a high speed buffer for this work. Use the compound sparingly, too much causes swirl marks.

You also can wet sand with 2000 or finer to remove imperfections.

dr bob

My typical annual treatment uses three or four steps, all of them way less than a medium cut compound. Paint cleaner, polish, glaze, wax. Medium cut compound is for serious new paint orangepeel or a follow-up step behind 2000-grit color sanding.

If you have clearcoat, stay far away from that medium cut compound. Also, if you haven't used a high-speed polisher before, do some practice on a junk panel before you go after the 928. Many salvageable paint jobs have been rendered worthless by amateur detailers with polishers. Knao your abilities and limits. The Porter-Cable is perhaps the best compromise, although it won't generate the heat needed to get the paint surface to seal itself during polishing.

Good luck with your project!

michaelathome

I had posted up last week some of the progress that I had made. The '88 guards red was in need of help. No clearcoat that I have seen. I used 3M Fine cut and followed with Maguiars Gold wax using an OTC orbital. I am sure that I will be trying better products but I was able to fool a few people at this weekends GTG. "We don't need no stinking re-paint!" I'd say that I have 10 or so lazy hours in so far.

http://members.rennlist.com/michaelathome/DSCN0237.JPG (Larger pic)

I still wanna get rid of some of these though. Small fine scratches. I am going to try to pick up a better orbital in the next few weeks as mine bogs down too much. The pink tinge I do not know if that is just the flash or more oxidation that I need to get off. I learned long time ago that you need to clean/prep till the rags are the same color of the cloths/products that you are using. Problem with non clearcoated cars that could take a LONG time and you can remove the paint.

http://members.rennlist.com/michaelathome/DSCN0215.JPG

I also need to figure out a way to remove the overspray from the rubber while still being gentile and really getting in the cracks/seams in a way that I am not going to take off the corners.

Bill Ball

The best stuff I have ever used is 3M Finesse-It II. Anything I put on after it makes the finish duller. Use it with your orbital and foam buffing pad. You work it with a bit (not much) pressure at first then let up as it dries and let the buffer float until it virtually disappears. This should get rid of all of the fine swirls and scratches. However, the paint on my 89 is so much trougher than paint finishes I have treated with this on our other family cars, that I really had to go at it for a long time and with more pressure than previously.

http://www.amazon.com/gp/product/B00...90520?n=228013

Bill Ball

I took the liberty of cropping the photo you provided in the link.

Those look like more substantial scratches than can be removed with these mild compounds. If this is single stage paint, it looks like it needs sanding 2000-3000 grit. Don't be afraid of sandpaper followed by your final cut. Try a small spot and I think you will see what I mean.

A better orbital buffer may be in order. None of the auto store buffers are up to the task. I have the Porter Cable 7424, shown here:
http://store.yahoo.com/tylertool/por746varspe.html

It's good, but even it requires a lot of buffing with the hard paint on the 80's 928. You may try that first before sandpaper.

Garth S

The clear coat used by Porsche is generally thick and rock hard - still, with a medium cut abrasive, it is all too easy to go through to the colour base: should that happen, no amount of buffing will ever make it shine .
The removal of scratches is not so much about cutting down the clear coat surface ( which obviously does happen) as it is about generating the 'correct' amount of heat to allow the clear to soften and flow. It is a delicate touch with the right tools and very fine compounds to get it right. Dr bobs post covers this and the risks ..... I've been 'schooled' in the technique and done some on regular cars; however, ir was a pleasure to stand back and watch my mentor wield the huge detailers buffer to 'warm up' the clear coat on the Porsche to lift some scratches.
The 3M Finesse-It II that Bill mentiones is great stuff, especially for an amateur like me. I did an entire F150 4x4 by hand with this stuff, and the clear coat/black came out looking nearly new. Too new ...now I'm concerned about taking it back into the woods ...

Bill Ball

Garth: I didn't know you could warm up and flow cured paint! Must be just a few degrees from causing a burn. I'm an amateur, so I'll stick with the Finesse-It II and the gentle orbital.

Kevin in Atlanta

I faced the the same kinds of issues with the black paint on my GTS. I used 2000 grit followed by Meguiers ScratchX applied by hand and am very pleased with the results. 2500 and 3000 grit is available at automotive paint suppliers and I would recommend them as well. It is good to know your abilities. Thats why I started with hand buffing. It is also just as important to know the paint. I'd suggest a visit to an automotive paint and body shop to get the details on your current paint.

Garth S

Bill, That's the best explanation I've had from two separate 'buffing' pros - that the clear coat can absorb adequate heat from the buffer during a fine compound cut to flow sufficiently to fill minor scratches. The best analogy I can think of is blowing glass - no movement until the temp is just right: a little too much and it collapses, or burns in the case of clear coat. I do not have any info to suggest that solid colour enamel type paints behave this way, only base colour/clear coat treatments.
Also an amateur, I too like the Finesse-it and the orbital power of my wrist: it may take more time, but it is very difficult to either go too far or to make an irreversible mistake.

SteveG

Garth/and Dr. Bob: I have what looks like acid rain etching in my black paint, it is very fine white water marks that are not merely water induced. Other than this the paint shines and I hate to paint it if I don't have to. I've used a wet clay bar, and then Maguires, but apparently the clay will only clean the surface. You are saying that the P/C orbital (which I have) will not generate the necessary heat. I am assuming the etching if that is what it is, is only in the clear coat and a certain level of heat will cause the clear coat to flow and (I'm hoping) the etching will disappear? Do I understand that the P/C will not do it and manual application (with practice) is necessary to cause the c/c to seal itself? or do I have to upgrade to a better orbital to get this heat? I'm inclined to practice with the orbital on a really old and ugly white van.

dr bob

Steve--

I have black, and suffered some acid damage to the hood from water thet resided in the wood garage door for a bit before it dripped on the paint. Then it sat for a few weeks since I was off on a project. It took a hand treatments to get it back. I started with a fine cut polish, by hand, and worked my way out to glaze in five steps. This was a relatively small area on the front of the hood, not the whole car, and managed to consume several hours to get it just right. If it was the whole car, I'd use the same fine cut polish with the PC polisher, and a wool bonnet. Switch to foam for all other subsequent steps.

The heat generated with the high-speed polisher can be substantial. This is exactly the reason why we are told never to polish in the sunlight, where the sun heats the pain unevenly before you ever get near it with the polisher. Work in a warm area but not in the sun. After that, it's an experienced eye and hands that will get you to success. As Bill points out, different cars and different paints flow very differently, so be gentle and practice in a less obvious area on the car. Resist the urge to put serious pressure on the polisher, instead let the weight of the tool and just gentle pressure do the work. It's easier on you and definitely easier on the car.

Last but not least, don't be afraid to hire the work out to a pro. They will have a much better chance of getting your paint back to a condition that easier to maintain, without the risk of amateur damage. Once the paint is in good shape from the pro, you'll be happier doing light maintenance and waxing yourself. The cost of a pro paint detail is way cheaper that having to repaint even one panel on the car after it's accidentally damaged. Just as we don't mount or balance tires ourselves because of the equipment costs and talent required, major paint restoration should also be left to the pro's. My opinion, of course.

SteveG

Bob: Thanks. Very helpful, I hadn't really thought it was commercially available to farm out anything less than a paint job, but since you mention it, I have seen ads for "detailing" and never thought of this as something I could pay for professional attention. Sometimes I see only what I need to see. It's an age thing. OT - not: I may buy a Razor phone. I haven't the slightest idea why, other than to try and be cool and get some points from my step son. And I don't really like him, just trying to feel less inferior and get some "points" , but if you read this far, you know that.

Garth S

Steve,
Is your black paint an 'enamel' solid colour or a base/clear coat system? If the latter, you only have ~2mils of clear to play with. If this layer is cut through to the flat colour coat, usually a respray of the panel is the only out.
Any of the items mentioned are abrasives, even the clay bars. That is why the concern about excessive heat build up with power tools exists - in a flash, the clear can be cut through or burned. The base colour is flat - and cannot develop a shine.
As Bob said, consider the Pros for the good items - practice on the 'beater'
There is no question that your P/C will do the job - but my confidence level is still highest by using hand buffing: If someone was paying me to do this ... where's the power buffer?
The point I raised re heat induced flow of the clear coat at defect edges may be 'urban legend' amongst the Pro detailers I've encountered; however, that is how they have defined to me that sweet spot they create and maintain as the buffer moves over the surface. Regardless, it is nice to watch a skilled operator in action.

jeff jackson

Garth...
(sorry to hijack), but my 86.5 is paint code L700...any way of knowing if this is enamel...or base coat/clearcoat ??