Raised paint dimple--Razor off?

charlestek

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I bumped into a rear bumper stop at a garage and managed to create two raised dimples of pain on the top edge of the plastic bumper surface. One spot cracked off a tiny fragment so you could see the primer.

I was going to try to fill the spots with Dr. Colorchip and squeege, except that the two tiny paint areas are raised, so I was imagining using an xacto knife or safety razor to skim and trim the paint raised above the surface.

I can't imagine wanting to sand down the dot, unless I had sandpaper glued to a pencil eraser. What's the best way to do this?
 
Found this in another thread:

DBAILEY DBAILEY is offline
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Re: Need Quick Help to Remove Paint Blob
You could fashion your own denibber. Take a razor blade (rectangle ones not the trapezoid ones for utility knives) and wrap some masking tape around the ends of the razor leaving the middle of the razor exposed that is just wider than the blob. place masking tape on each side of the blob. Lay the razor flat on the panel and slice the blob off gliding in along the tape. Then you have less wet sanding to worry about.

Sounds crude, but it works.
 
I can't imagine wanting to sand down the dot, unless I had sandpaper glued to a pencil eraser. What's the best way to do this?
A sandpaper glued to a pencil eraser (on the back end of a pencil) is a very dangerous tool. For one you'll have a hell of a time holding it perpendicular, which will result in uneven sanding. The other is: you'll work only a small area with it, which will create a visible "hole" (low spot) in the clear coat, and you won't be able to blend it in properly - unless, of course, you sand down a larger area with a larger pad, which then defeats the purpose of you doing it with a pencil in the first place.

Because of that I'd recommend you use a rubber-foam wet sanding backing pad with 4000 or 5000 grit sandpaper, which is perfect for removing tiny, spot-like defects (like touch-up spots for rock chips). Flexipads has a nice wet sanding backing pad, which is relatively big (almost 6"x3"), but you can just cut a small piece off it (like a 1"x3", or even 0.75"x1.5" piece), wrap a small piece of sandpaper around it, and use that. This will enable you to work on a very small area, yet avoid creating a visible low spot, and easily blend it in to the rest of the paint.

Honestly, I can't imagine the razor method working properly, because you won't be able to hold and push the razor perfectly parallel to the surface, but only at an angle, which will result in you cutting into the clear coat. A razor blade will also be a lot wider than the dimple you're trying to remove, and than the small piece of wet sanding backing pad I've described above - so you will most likely damage or at least affect a bigger area with it anyway.
 
itsgn,

Thanks for your reply. The trouble is that the raised dimple is on an edge of the bumper, with the bump of paint straddling below the edge vertically and above the edge horizontally where the flexible bumper got pinched.
I should have just left well enough alone. I tried some Dr. Colorchip, but the blending solution did not dissolve the dried Dr. Colorchip paint easily and caused the middle of the dimple to pop out leaving a tiny cavity.

I had bought some really fine grit sandpaper from autogeek a few years ago, I have to check if I have a grit that high. I didn't realize there was a grit above 2000. I do have some flexible backing somewhere, I have to poke around in the cellar. If I masked the area to leave only the raised area exposed and tried a .75"x1.5 piece of backing. Are flexipads sold on autogeek?????
 
The trouble is that the raised dimple is on an edge of the bumper, with the bump of paint straddling below the edge vertically and above the edge horizontally where the flexible bumper got pinched.
I'm not sure I understand your problem - but if you think it's important that I do, then you could attach a photo or something, which could clarify the situation.

I tried some Dr. Colorchip, but the blending solution did not dissolve the dried Dr. Colorchip paint easily and caused the middle of the dimple to pop out leaving a tiny cavity.
That's normal for any application of a relatively thick layer or droplet of touch up paint. It happens because as the paint dries out, it shrinks, and that leaves the tiny "air pocket" in the middle. It can be fixed by re-applying the touch up paint in the affected area - even though that's only for perfectionist, because the air pocket is usually so small, that it won't be noticeable, and waxes or sealant won't create a white spot in it either.

I had bought some really fine grit sandpaper from autogeek a few years ago, I have to check if I have a grit that high. I didn't realize there was a grit above 2000.
Of course there are. Actually, 2000 is the lowest grit sandpaper recommended for wet sanding, because anything lower won't be fully smoothed out by most compounds, and will leave behind scuffmarks or hazing. With 4000 or 5000 grit sandpaper you don't have to worry about that, because even a single pass of any regular compound will remove the hazing caused by them, and they're also fine enough so you don't burn through the clear coat in just a few dozen of passes with them.

I do have some flexible backing somewhere, I have to poke around in the cellar.
Well, the point of the sanding backing pad I've recommended actually is, that it's relatively stiff, which ensures that you'll get an almost even pressure on its whole surface, and you won't abrade only there where your fingers would be pushing through the material of a softer pad. Of course the pad is not completely rigid either, and the two sides of it have different hardness/thickness, but you can't really bend it either.

If I masked the area to leave only the raised area exposed and tried a .75"x1.5 piece of backing.
It's usually not recommended to mask the borders of the sanded area off, because then you'll get sharp edges there (with the inside area being sanded down, and the masked off area untouched), which will be noticeable as frame, after you remove the tape. Rather, you should blend the sanded down area in with the rest of the paint, by doing a few passes with the sandpaper also outside the actual defect area (obviously with the less passes and the less pressure, the more away you get from the target area). Of course we're talking here about usually relatively small areas (like +10-15% max.) to cover extra.

The only exception of the "do not mask with tape" rule is if there's a different panel or material (like plastic trim), you don't want to scratch with the sandpaper, because then there will be a sharp edge anyway; and tapes lines used for orientation only, which are only there so you can know where your scratch/defect is, but which you won't actually sand up to (ie. your sanding marks won't reach to and "touch" the tape).
 
"That's normal for any application of a relatively thick layer or droplet of touch up paint. It happens because as the paint dries out, it shrinks, and that leaves the tiny "air pocket" in the middle. It can be fixed by re-applying the touch up paint in the affected area - even though that's only for perfectionist, because the air pocket is usually so small, that it won't be noticeable, and waxes or sealant won't create a white spot in it either."

I now think of this job as not so much necessary cosmetically, as a way to train me to see if I can make a small paint repair. I'll try to get a picture tomorrow, but I don't have a macro lens or close up lens for my camera.

The dimple is a raised area of paint that happened because the flexible bumper and flexible paint got mildly squashed against a vertical garage barrier pole and at the contact point of the horizontal perpendicular edge of the bumper some of the paint got squished upward or extruded into a raised area. There is a solid horizontal trim bar on the lower bottom of the bumper that took most of the force.
When I applied the Dr. Colorchip it probably dissolved some of the original paint in the center of the dimple that had fractured and when I used the Clearact it caused the tiny bit of paint in the center to fall out, leaving a tiny cavity. Were only talking maybe 2-3mm wide, 1mm deep and maybe 1mm high at one spot on the perpendicular edge of the rear bumper.

Well, the point of the sanding backing pad I've recommended actually is, that it's relatively stiff, which ensures that you'll get an almost even pressure on its whole surface, and you won't abrade only there where your fingers would be pushing through the material of a softer pad. Of course the pad is not completely rigid either, and the two sides of it have different hardness/thickness, but you can't really bend it either.

The only pad I have is a black Meguiar's sanding backing pad E-7200. Will that do?

I understand what you mean about the masking tape. I really just want to avoid prevent putting scratches/swirls in paint areas to far away from the problem spot.

Amazon sells some 3M 5000 grit paper, I will try that. As I said before, if I just let it be without doing anything, the damage was hardly noticeable, now I made it slightly worse, and I would prefer not to make it even worse, though I need practice. Hopefully 5000 grit will just plane the high spot down. Though I'll have to fill the middle of the cavity with an extremely tiny dot of paint first and let it dry. It appears that the force of the extrusion on a 80 degree day here pushed/etruded the paint into a raised area with maybe a spot of air in it or tiny fractured micro chunks of paint with some cracks in between.

I am having trouble with the sealact and the Dr. Colorchip paint. It is a black honda accord and the Dr. Colorchip paint, I only let dry maybe 10min and could not dissolve/blend it with the sealact. The sealact also made the black Dr. Colorchip paint turn gray from deep black. I am going to talk to the Dr. Colorchip folks.
 
The only pad I have is a black Meguiar's sanding backing pad E-7200. Will that do?
I don't have experience with that particular product, but from what I know of it, it's essentially the same as my Flexipads pad. The problem is: as it is, it's too big to limit the sanding to an inch by inch area or so. So, you'd need to cut off a smaller piece or stripe off it (I did it with a carpet knife, but a scissor should be good, too), and wrap a small piece of the sandpaper around that (in a U shape, obviously) so you will have more control over the area you're sanding.

Amazon sells some 3M 5000 grit paper, I will try that. As I said before, if I just let it be without doing anything, the damage was hardly noticeable, now I made it slightly worse, and I would prefer not to make it even worse, though I need practice. Hopefully 5000 grit will just plane the high spot down.
Obviously you will need to work it more than a 2000 grit sandpaper to abrade the same amount of clear coat, but in return your will be able to remove the sanding haze in just a single pass with a medium cutting pad and a medium cut (or even probably light) compound. And of course you will have - again - more control over the process, and for ex. won't remove more of the cleat coat than necessary and needed, just because you only checked after 10 passes with the sandpaper over the spot, and not after every second.

If you do remove too much, you'll have the same problem as with the original dimple of the touch up paint, ie. that if you look at it, it will not be perfectly flat, but you'll see a valley in the paint. And of course if you remove even more, you might burn through the clear coat. This will be still possible with a 5000 grit sandpaper, but you'll have to work harder to do it, than with a lower grit sandpaper (which will cut faster). Of course a paint thickness gauge is a must here to avoid serious mistakes, even though the affordable ones won't work on plastic parts, so there you'll have to fly blind, and go by feel and expertise.

Also make sure to wet (spritz on) the sandpaper over and over, so it won't clog up with the already abraded particles from the clear coat. This can happen more easily with a 5000 grit sandpaper than with a 2000 grit sandpaper.

Though I'll have to fill the middle of the cavity with an extremely tiny dot of paint first and let it dry. It appears that the force of the extrusion on a 80 degree day here pushed/etruded the paint into a raised area with maybe a spot of air in it or tiny fractured micro chunks of paint with some cracks in between.
Again, I'm not sure I understand exactly what you mean, but if your touch up paint has cracked, then you applied it too thick, and you need to redo it with a thinner coat, or multiple coats, if necessary. Otherwise the cracked will accumulate dirt and water, and will get uglier and uglier, and ultimately the paint will peel off. And if the paint has cracked around the edges of the touch up, then you didn't clean the surface of the defect correctly, and the touch up paint could not bond to the existing paint.

I am having trouble with the sealact and the Dr. Colorchip paint. It is a black honda accord and the Dr. Colorchip paint, I only let dry maybe 10min and could not dissolve/blend it with the sealact. The sealact also made the black Dr. Colorchip paint turn gray from deep black. I am going to talk to the Dr. Colorchip folks.
Sounds like you used too much of the solvent. Also, black paint is the finickiest and the hardest to repair properly. (Well, it's hard to do touch-up repair properly anyway, but with dark and especially black paints, it's a challenge even for pros.) So, don't expect perfect results, because you just won't be able to get that.
 
Again, I'm not sure I understand exactly what you mean, but if your touch up paint has cracked, then you applied it too thick, and you need to redo it with a thinner coat, or multiple coats, if necessary. Otherwise the cracked will accumulate dirt and water, and will get uglier and uglier, and ultimately the paint will peel off. And if the paint has cracked around the edges of the touch up, then you didn't clean the surface of the defect correctly, and the touch up paint could not bond to the existing paint.

We're talking a 2mm long raised area that came from the original oem paint being pinched as the bumper bent. In the middle somehow the Dr. Colorchip paint (paint plus carrier solvent) combined with the oem paint and loosened a tiny amount in the center that got lifted off with the sealact, so there is a very tiny depression cavity.
 
Just make sure that it's really just the paint that somehow got pinched and raised to create that bump. Because if the actual panel material (metal or plastic) below it also got pushed up, you won't be able to sand down that bump. Even if it's just the paint that got pinched, you will still most likely have to burn through the clear coat (and possibly also the base color) to level it with the surroundings - unless your bump is just a few dozen microns high. If the panel material is plastic, you might be able to sand it down (with a lower grit sandpaper), but then you'll now have a larger area to touch up with the paint, resulting in possibly an even more noticeable spot (unless you can get it somehow perfect).
 
itsgn,

Great observation. I should have left it alone in the first place.
 
itsgn,

Great observation. I should have left it alone in the first place.
 
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