Alot depends on the colour of course. If your paintwork is not mettalic (like mine) then its alot easier to repair. Metallics use a clear laquer over a base coat and are a nightmare to try to patch up/blend.
Thanks LoBsTeR - and thanks for pointing that out, I didn't mention the metallic aspect. However, all is not lost (see bottom...)
The main problem is that with a brush touch-up it's impossible to get the metallic particles to coincide with those that were sprayed - so the touched-in paint usually looks darker for light colours - but sometimes lighter for dark colours...
I don't bother trying to put a clearcoat over the basecoat when touching up scratches - I find it's better to build up the level with basecoat and then give it a quick shine with compound. The result is durable enough - trying to add a clearcoat over the whole job is probably going to give contamination (dust) or flaking issues, or highlight stonechips, and you may as well sand/repaint completely.
It's unlikely that adding a clearcoat will disguise a metallic-matching problem. Repainting the whole panel will solve the problem provided the paint is matched well (mixed to original recipe). If going onto an existing respray, there might be problems. If you're using a proper spraygun, you can 'fade out' a non-matching metallic into the middle of a panel - the metallic can be applied very thin and dusty because the clearcoat will later smooth over it. The result will be less noticeable than having a hard mis-match at panel edges, but it takes practice to avoid a 'halo' effect around the wetter basecoat near the fade-out. Fast thinners and not over-applying anywhere helps. My best success was where I managed to avoid repainting a whole roof by doing a fade-out, from a rear quarter repair, part way up the C-pillar - not an easy place since it's 'on view' and in the light. But it can be done!
(In summary - LoBsTeR, you are right, metallics can be a lot of work to patch properly
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In contrast, I've attached a photo of my Stilo's left mirror as I got it, I touched it up quickly a few months ago, and the other photos are taken just a couple of minutes ago. Lighting conditions are not the same, but I think the scratches are less noticable (I had to be careful with the angles to highlight them). Dark metallic purple must be the very worst colour to work with
If I'd spent a bit longer (over several days) to properly fill-in the scratches with touch-up paint (they were quite deep, fingernail-snagging) then it would look better, but in the meantime I'm happy enough. My feeling is that it took about fifteen minutes to get this result, versus probably four hours split over two days to remove/prepare/repaint/re-clear the mirror shell - and that can still be done later if there is further damage while in my care
In general, touch-ups are less noticeable on any part of the car below the level of the bonnet/door handles (the 'eye-line'), and also less noticeable on light colours.
And before doing anything else... the thing to do first is to get a really good cutting compound, such as the 3M Perfect-It III, and patiently polish away at the 'scratch' for a few minutes - in many happy cases, the 'scratch' turns out to be merely paint transfer from another object... and most of it disappears
-Alex
