How to work on hard clear coats?

I've been working on a 2009 BMW Z4 over the weekend and I can't seem to get the fine scratches out of the hood. I've been using M300 and a mf buffing pad and would work quite a while on the hood, but with very little improvement. I made sure to spray the pad with some quick detailer every time it looked like it started getting too dry

Now I've already "finished" the detailing for this time (I'm in no rush to get this done), but I would just like to know what to do the next time I have time to go over the hood. It seems like the rest of the car is in pretty decent condition and d300 and an mf pad seemed to get the paint on every other body panel looking great (maybe except for the roof).

Should I try and use a foam pad? or does a really hard clear coat just require more time?

 

What other polishes/compounds do you have access too? I would do a couple of test passes on the hood or roof with other combos (going from least to most aggressive) to see what gave the best results. Also, just from reading the "Pre-polishing pointers" thread in this same sub-forum, it seems that some BMW's do and will take more time, but take that advice with a grain of salt.

 

How much pressure are you using? You need atleast 10-15 pds of pressure with slow passes when using the D300 and MF Cutting discs.

 

Are you priming the pad with D300 or just detail spray?

 

I am priming the bad with d300 and spraying to keep everything wet. I'm using about 10 pounds of pressure, and d300 is my most aggressive compound/polish. Other than the mf pad, my next most cutting pad is a uber orange and i'm using a 7424xp

 

Try using more pressure, cleaning the pad more frequently(a couple of times per panel and with compressed air if you have it), smaller work areas and more passes. Or step up to M105. On hard clear, even M105 will take multiple passes.

Where are you located? Someone might be able to give you a sample of 105 if you need it.

 

is the car black

 

BMW's are a strange breed. I have had some that didn't seem too bad and I did a dark blue one last year that was like a rock. I may be old school, but I still think those that are going to take the trade seriously should learn the rotary polisher first. I know there are guys who will disagree, but it is times like this where certain know-how comes in handy. Like Ken, I was a rotary only user for a long time, and although I have seen the light with a DA, its not going to break me if a DA doesn't work.

 

X2 on being picky- I've corrected on close to every color they offer, from my experience most of the metallics such as sapphire black and the monaco blue are pretty hard. And then there's Jet Black......... ha

 

Yea that jet black is the odd one out of the bunch. crazy soft paint. Thought the BMWs I've corrected were never super hard as the op described

 

The hardest clear coat I've dealt with was this Orient Blue Metallic E46.. But my dad's E92 Black Sapphire Metallic is middle of the road.

However, since clear coat gets harder over time, it's tough to point a finger on clear (no pun intended). So it's a balance between age of paint and paint type.

I can tell you that when I did the hard Orient Blue Metallic paint I was sore the next day from using so much pressure.

 

I do all color Bimmers constantly and have only used Rotary Power and the Lake Country Hydro-Shred Pads, Cyan, then Tangerine, and Menzerna polishes. Never had to use the Foam Wool Pads or Megs 105 on them, except for a couple of really badly swirled Jet Black M5's. The 105 and PFW/205 Tangerine turned them into rolling black mirrors.

I would say that most of their paint is medium to hard, but workable with a Rotary all day.

Good luck, are you sure you want to remove every defect on the hood and roof, and not just tame them down, so they are less noticeable?
If they keep getting the same scratches, etc., from improper washing, the car wash, etc., you may not ever be done with this.
Sometimes,, you just have to cut it and go on. If they are not wanting a full correction with every last mark out, then maybe you are good to go??

Dan F

 

The color is deep sea metallic blue.

While working on it, I was almost scared to use too much pressure. I did two passes with about 10 pounds of pressure, and didn't want to press my luck and find out that the clear is really thin (especially with the roof having so many edges to it, I tried to be careful not to burn through that).

And as this is my family's car, I'm not too pressed on getting every last defect out, it would just be nice to have a really nice shine on the hood (as it seems to make up 60% of the car... it's a huge hood on a small car).

How much pressure should I be using though? And and what speed should I be making my passes? Like a 1 square foot area every X amount of minutes.