Need advice on a recent detail of a black Nissan Maxima

[olenderc]

My friend asked me to detail his 90,000 mile black Nissan Maxima for him, and since I am still learning and need the experience, I am only charging him $150 only to cover the expense of supplies I would need. The paint was in pretty rough condition, fairly deep scratches in various places; the front bumper was a war-zone with chips everywhere and paint starting to crack, chip and peel away in certain places.

I washed his car with a mixture of CG Wash and Gloss/ONR and clayed it with a speedy prep towel.

I then got to work on the hood doing test spots until I finally settled on doing about two passes with WF Uber Compound on a 6" Meg's Microfiber Cutting Pad, followed by WG Finishing Glaze on a white 6.5" LC Flat pad. This was all being done using a 6" Griot's Garage DA.

Finally since I wasn't going to be able to finish the whole car in one shot, I was basically working panel by panel and when finished with one, I coated the paint with DP paint coating which I just recently bought to try out.

There were a few spots where I went with an additional 2 or so passes (for a total of about 4) with the Uber Compound because of heavier scratches, some of which I couldn't get out so I didn't push my luck since I didn't have a paint thickness gauge.

I was a little discouraged because I couldn't get the paint to a standard where I was completely happy but I was trying to stay realistic with what I was given. I couldn't even paint correct the front bumper because there were so many chips and cracks I was afraid I'd peel the paint right off in some spots; I recommended he might need his front bumper repainted if he wanted to.

Some of the scratches, however, I was a little disappointed I couldn't get out. A number of them failed the fingernail test so I figured those I would never be able to fully correct them. There were a few that didn't catch on the fingernail that I tried to correct with no luck. One scratch in particular on the roof, I did manage to get out for the most part, but required about 6 passes with the Uber Compound, which I wasn't really comfortable doing but my friend wanted to see if I could get the scratch out any more.

Working for about 7-8 hours I manged to correct and coat the hood, front fenders, and hood of the car. Needless to say, I'm a little bummed because it didn't go as I wanted it to in terms of correcting to perfection. I figured with a MF cutting pad and Uber Compound I wouldn't run in to many roadblocks. Is Uber Compound not as heavy as I thought it would be? Not really sure what I was doing wrong..any advice?

[zmcgovern45]

You are not going to have great luck chasing RIDS with 6-6.5" pads... I would have recommended 5.5" pads for the majority of the vehicle and 3" MF pads for those deep RIDS if needed.

Remember, the larger the pad, the less cutting power you will have.

Pressure = Force / Area, therefore more area equals less pressure at the face of the pad (assuming the same exact pressure is used regardless of pad size).

Example Calculations:

Area of a circle = pi * r²
(assumed to be exactly 3.14 for these calculations)

Therefore the calculated areas are:
6.5" pad = ~33 in²
5.5" pad = ~24 in²
3" pad = ~7 in²


Using the areas, and an estimated constant pressure of 15 lbs. we are able to determine the pressure produced using the different sized pads:

6.5" Pads: 15 lb / 33 in² = 0.455 psi
5.5" Pads: 15 lb / 24 in² = 0.625 psi
3" Pads: 15 lb / 7 in² = 2.143 psi

So you can see that a 3" pad generates almost 5X the amount of pressure with no additional force required.

[parttimer]

I use a 6.0 pad on my Rupes for general work. If there is a bugger of a scrach, I use my GG with a 5.25 pad and Uber which worked well yesterday. I have a 3.25 for detail work. So try a smaller pad and I don't think 6 passes is excessive, many people use 6 according to some of their posts.

[olenderc]

When I bought my GG 6" DA, it came with the 6" backing plate so I kinda just went with 6.5" foam pads. If I do ever buy a 5" backing plate and 5.5" pads, I feel like the 9 or so pads of various colors I currently have will be useless and a waste of a decent amount of money.

I do have the spot buff 4" kit and I did buy a 3" meg's mf cutting pad too, it just didn't even dawn on me to use for the various RIDS. I figured if 6 passes of a mf cutting pad with a compound couldn't get it out, not much else would.

I appreciate your response though, those calculations help put the amount of cutting power each pad size has in perspective. When I finish out the rest of the vehicle I'll have to try the 3" pad on the various RIDS.

[rmagnus]

Is Uber Compound not as heavy as I thought it would be? Not really sure what I was doing wrong..any advice?

I don't think you're doing anything wrong. Deeper scratches really need to be filled before leveling with sandpaper ot compound. You should have a paint guage if you're really going to try and correct damaged paint. You may not be the first one to attempt compounding.

I thought Uber Compound was the "Perfect Compound". Sounds like you need a few more passes. I use M105 most of the time and more recently M101. Neither are perfect but do correct very well followed by M205. I'm old school and like wool pads vs mf. I also prefer direct drive buffers and use Flex 3401 and rotary more than mf pads.

Sounds like your system was working you just needed to stay with it more. Lets face it a black car and trashed paint is a healthy challenge. As far as bumpers go when the paint is flaking off you really did the right thing by staying away from it. That really needs to be resprayed.

I think you got what you wanted, made the car look better and got valuable expierence. Pick up some smaller pads they will help on the GG polisher.

I've got a single stage 1960ish VW bug to correct in the near future. It will require banging out some dents in the right fender and blending some color into damaged paint. It's a project for a friend so I'll be in a similar situation. Just a car I really wanted to work on and bring back to life. It's been resprayed with single stage paint once but everything else is original.

[olenderc]

Unfortunately, since detailing is not my full-time profession, I can't justify spending hundreds or even a couple thousand on a paint thickness gauge. But I do agree with you that it is definitely a needed tool for heavy compounding and correction of deep scratches.

Don't get me wrong, Uber Compound was great, it practically finished out LSP in most people's eyes, I guess I was just expecting too much out of my first real experience with a compound and heavier scratches. It was leaving behind a smooth reflective finish, with the few prominent scratches still annoyingly visible. But I did try to play it safe and figured about 2 section passes (about 4-6 overlapping passes each) in most areas and anywhere from 4-6 section passes in more stubborn areas to be a fairly safe bet since the car had never been polished.

Thanks for the input magnus and everyone else whose commented so far.

[olenderc]

Another thing I forgot to mention is, using the DP coating prep polish (good thing I only used it on a test spot). I tried using this on a LC black pad at about speed 3, and the combo was leaving behind micro-marring which required me to re-polish using a white pad and finishing glaze. I decided this wasn't going to work, and switched to hand application using a small green microfiber pad, which actually went a lot faster than machine application.

Not sure why a black pad would leave behind micro-marring, then again maybe it was the black paint. I will admit I didn't prime 100% of the pad with product (since it was fairly "liquidy" to begin with) but I definitely gave a hearty circle of product over the entire pad, maybe that wasn't enough.

[rmagnus]

Zach posted a thread about an affordable paint thickness guage available on your fav e auction site. Nicety CM8801F, I bought one about 3 years ago for $130ish and it was one of the best investments I ever made beats paying for the Defelsko unit.

I don't detail for a living either so I understand about over spending for equipment. That said its important to have the right equipment which helps avoid making mistakes. My paint guage has paid for itself many times over and allowed me to make corrections otherwise impossible to do.

It's thought to burn through healthy CC with a DA if using common sense. I still find filling scratches prior to leveling the best way to repair and sev as much clear as possible.

I haven't used my supply of DP coating yet but find it weird that polish on a black pad left marring. It's just meant to remove polishing oils. I don't usually post reviews but have a couple fun projects coming up where I will do so. One will include the DP Coating.

[olenderc]

Thanks, I'll have to check out that paint gauge one day!

[zmcgovern45]

You'll find that the majority of us don't detail for a living, but if you're going to be working on other people's vehicles, this is a tool that I highly recommend.

http://www.autogeekonline.net/forum/product-reviews/61505-cm8801fn-paint-thickness-gauge-affordable-everyone.html

[HateSwirls]

Sounds like you did all you could and the results you see it what you'll have to live with unless you want to wet sand which I don't recommend unless you know what your doing.
I agree on using small pads , I switched to 5.5 inch pads and must say I see a big difference but for deep scratches I don't think I'd see much of a difference.

I tell my customers up front that whatever imperfections we see once I'm done is what it is, I tell them I'll do the best I can and that's what I do.
Do the best you can with what you know and be happy with the results.

I never fault myself if I did all I could , sometimes I'll spend and entire weekend on a car and still not get it perfect but man what a difference it makes with the hard work we out into a job.

[olenderc]

Sounds like you did all you could and the results you see it what you'll have to live with unless you want to wet sand which I don't recommend unless you know what your doing.
I agree on using small pads , I switched to 5.5 inch pads and must say I see a big difference but for deep scratches I don't think I'd see much of a difference.

I tell my customers up front that whatever imperfections we see once I'm done is what it is, I tell them I'll do the best I can and that's what I do.
Do the best you can with what you know and be happy with the results.

I never fault myself if I did all I could , sometimes I'll spend and entire weekend on a car and still not get it perfect but man what a difference it makes with the hard work we out into a job.

What things do you notice with a 5.5 in pad vs a 6.5 in pad? Fewer passes needed to achieve more complete correction? Also you mention it does not do much in terms of deeper scratches, is this where you'd see more with a 3-4" pad?