Paint defects - water spots or something else?

[heinzbush]

Hi All,

I am trying to get the paint of my 993 perfect and worked so far with Ultimate Compound and Ultimate Polish. While in general, I get ok results, when I use a flash light, the clear coat still looks like it has many defects which are not swirls, scratches, etc... but rather like tiny "craters" or "small embedded areas": am I right these are watermarks? I probably should hit with something more aggressive like M105?




here is a good picture in full resolution: Dropbox - IMG_1286.jpg


An additional, major defect is on the engine bonnet... looks like it goes through the clear and paint all the way to the metal... any tips on how to "attack" this? I guess respray is the only way...


here is another good picture which for some reason doesnt upload: Dropbox - IMG_1248_.jpg

[itsgn]

Unfortunately your pictures are very small (even the "full resolution" ones), so, it's hard to say, but I tend to see the defects in the last picture having a very sharp, yet thin line, and a zigzag-like pattern. Which I wouldn't say are typical for water spots, because in my experience those are more round and their edges less sharp usually. However, I remember having seen similar patterns of defects on cars that had tree sap or pine tar sitting on them, and that ultimately ate through the clear coat, down to the very metal. Once the sap and resin was removed, the defects in the clear coat had the very same zigzaggy pattern.

And the other pictures with the many spot-like defects look like tiny rock chips to me, like what you'd get if somehow gravel would hit the paint in large quantities, yet at relatively low speeds. That said I also think I see tiny hairline like defects in those pictures, which I guess would be typical for either a very heavy direct physical impact at that spot, or signs of imminent clear coat failure, when it would start to peel off soon. These defects could be also the sign or result of a very poor aftermarket (re)paint job.

Did you measure the paint thickness at the pictured areas? What were they, compared to like door sills and unaffected areas?

[ZiggyPopp]

Has it been repainted? Sort of looks like orange peel.


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[heinzbush]

Thanks a lot for all your answers...

with regards to the finer defects (the first part of my initial post): I only have a magnetic paint thickness scale (one of these pens) which indicated green (no respray anywhere of the car and normal paint thickness) when I bought the car. I dont have it with me right now as I borrowed it a friend of mine.

I tried to get better pictures and I uploaded them on link below. The pics are actually quite big, you have to zoom in to 100% to see it really large.
The defect is difficult to describe and not everywhere as bad as on the pictures. Keep in mind, the car is 23 years old and probably never had paint correction done... from a foot away, the paint looks perfect and mirrors nicely, however if you get really close you can see that the surface is simply not even, but has these small craters / "ups and downs"...

The pics are from the rear fenders of the 911 where it is worst... I guess since this area is prone to stone hitting, water drops staying on, etc.

Pictures


The second (deeper) defect could very well be from tree sap. Crazy that this goes all the way through the clear, paint, all the way to the metal. It is on the back of the car. You think its worth trying to try to fill these many tiny holes with a color/clear coat mixture and then wetsand?

THANKS!!

[itsgn]

Well, you could buy a relatively cheap, yet good paint thickness gauge with an LCD display for about $150-250, that actually tells you in microns (with an accuracy of a few microns) of how much paint you've left on a metal substrate. They won't work on plastic bumpers (you'd need more expensive one for that, that cost >$1000), but will work on essentially all metal, even non-magnetic ones.

The thing is: even if you're not a professional detailer a proper paint thickness gauge is essentially a must when doing anything more than just light polishing on a car, because every time you do any kind of serious compounding, correction or wet sanding, you run the risk of burning through the clear (or if it's single stage, then through the base paint) to the point where the panel has to be repainted. So, it could very well pay for itself even for the first time.

The problem with these pen type gauges are that they're not very accurate, and they're only telling you very roughly about the thickness of the paint, which hinders you in making a proper assessment of how long you can go on with sanding or compounding before you're risking ruining everything.

As for the pictures:
1. Regarding IMG_1300 and IMG_1302: they still look like tiny impact damages to me. You could try correcting them with either compounding, or if that seems insufficient, then with wet sanding, but I wouldn't recommend trying anything without a proper thickness gauge. Or if they're only obvious when inspected closely and in focused light, but not reallt noticeable from regular pass-by distance and in everyday ambient light, then you could just leave them as they are, as they will be noticed by no-one.
2. IMG_1304 and IMG_1309: I'm not sure what to make of these, or where to look at. Actually 1309 looks like regular orange peel to me, but this could be also because of just the picture.

As for the tree sap damage: the problem is twofold. For one, the actual crack in the paint going down to the bare metal is usually not wide enough to be properly filled with paint. You can try it, but you will either create a huge (well, relative to the width of the crack) paint bump over the spot, or anything that you put in the crack will be removed at the first attempt to compound it. And the second thing is: the crack itself is just a small portion of the defect, as tree sap usually falls and sits in a drop shaped form on the surface, because of which the damaged area is usually larger than the crack; it's just the where crack is where it has eaten completely through the paint. But the damaged areas as a whole is larger, so, you might have compromised - or even already missing - paint in a larger spot. And this is where a proper thickness gauge comes in the picture again - because I heavily advise you to do anything aggressive to that area without assessing its current state, and the amount of paint still remaining there.

The problem is that once you try to touch up that area with a "larger" amount of paint (that will actually remain there), you'll have to wet sand it flat (otherwise it will look even worse with the touch up paint that it does now), and unless you've enough wiggle room left for that, you're risking burning through and compromising even larger areas of the paint - which obviously does not make any sense, if you want improvement, not degradation of the current state of the paint.

[heinzbush]

Thanks a lot for the answer...

with regards to IMG_1304 and IMG_1309: this is how it looks when you move further away... so the damages on the first two pictures are taken very close..

I understood that there is nothing to be done at this stage without a paint thickness gauge, so this is what I'll get now and come back to this thread after measurements!

[heinzbush]

... oh since you mentioned you were not sure what to look at I indicated it on the pics... It is very hard to capture with a camera due to focus / reflection... basically wherever it hits the light, the surface is not smooth and there are tiny craters, defects...






Big resolution on dropbox:

Dropbox - paint2 - Simplify your life

[itsgn]

What machine did you use to work on this paint and how long did you work it? I mean, like, did you keep going over and over the very same section, very slowly, or for more than a few passes, and for longer than one or two minute(s)?

[heinzbush]

What machine did you use to work on this paint and how long did you work it? I mean, like, did you keep going over and over the very same section, very slowly, or for more than a few passes, and for longer than one or two minute(s)?

Hi,

I have a DA polisher, went over it with 3 passes, not for a long time, "average speed" and nothing aggressive (soft foam pad, Ultimate polish)... KEEP IN MIND: these defects are not introduced by the polishing. They were there before... I'm just looking for a way to get rid of them... but wont go aggressive (e.g. M105) without getting a paint thickness gauge first...

[itsgn]

Okay, I just asked, because if you work the pads on the paint too long, with no pause in between, similar defects can arise from overheating the paint. But then this was obviously not the case here.