Problem After Sanding Down Touch-up Paint

[slvrshadow94tt]

Hopefully someone can give me some good advice.



I repaired a chip in the paint on my driver side front fender over the weekend. I followed "David`s" chip/scratch repair instructions that I printed off the Autopia "Learning" section.



I wet sanded the touch-up paint down to the level of the original, first using Meg`s Unigrit 1000 and then Meg`s Unigrit 2000, pulling the block toward me only. Then I followed up with 3M`s Perfect It II to take off the scratches left by the Unigrit blocks. It looked awesome until I changed my viewing angle in the light.



PROBLEM:(

Now it appears that the level of the clearcote around the touch-up is lower than the level of the paint repair, creating a "DING" effect when light reflects off the surface! Looks like I fixed one problem and created another:wall !!!!



What can I do to fix this? Should I purchase clearcote touch-up paint at the dealer and build up around the chip? And will clearcote touch-up applied over factory clearcote create any unwanted effects? How can I avoid this problem on future chip repairs?

[BA_Titan]

I had the exact same problem on my wifes` Envoy hood. It looked like a small dent almost. I used a small amount of clear and helped a bunch! I`m the only one that can tell where it is now.

[slvrshadow94tt]

EXACTLY:eek:



It now looks like a small dent instead of a paint chip. And now I`m worried even more since I have about 10 more chips to repair.



To anyone and everyone who can offer advice, techniques to repair this "ding/dent" effect and offer advice or techniques to avoid it in the future..........................:bow :bow :bow

[Gonzo]

Yes, please adivse. I have a number of very sloppy touch ups about a year old - done when I didn`t know any better. I`ve been to a couple of body shops and been quoted any where from $1000 to $1800 to repair the damage I caused and repair the as yet untouched stone burises and chips.

[Ryan]

I think your mistake was trying to sand the affected area only. Instead you must sand a larger area, say 1` X 1` surrounding the touch up. That way it wont get gouged.



Ryan

[slvrshadow94tt]

I thought the idea was to wet sand as small an area possible to avoid taking off more clearcoat than necessary:nixweiss .



It seems to me that if I had sanded a larger surface area, it would have created a "depression" in the reflection as opposed to a "ding".



Maybe some paint/touch-up pros can get in on this thread and educate us all :bow Certainly someone has encountered and "fixed" this type of problem before and can offer all of us advice on how to avoid this. Special techniques?? David Bynon.... you out there?:confused:

[03WRXMA]

Id like to hear from the pros as well........

[slvrshadow94tt]

:nixweiss ????



Should these questions be forwarded to a different forum?

[slvrshadow94tt]

:confused: :(



Perhaps this question should be posted to "Autopia University" :rolleyes:



Looks like I`ve discovered a question that can`t be answered or perhaps the right autopians have not read this thread.:nixweiss

[jr weeks]

Well, you may disagree with my opinion on this, but here`s a take from someone that`s been color sanding for 20 years;



You can`t wetsand specific small spots more than a pass or 2 (with the paper) without encoutering this. You will notice "cratering" or a slight depression if you work a while at leveling the touch up, ESPECIALLY on black or dark colors. The human eye is not a good indicator on judging just how much you can sand an eraser-sized paint touch up in order for it to be level to the surrounding paint-WHILE you`re doing it. It sure is after it`s buffed out and seen in contrast though! You have to spread out your blocking to the surrounding area, sometimes as much as a 1/2 foot or more, in order to blend it and also to spread out the way you are cutting out the orange peel-otherwise your touched up spot will also be crystal clear flat and 2 inches away you`ll have oem orange peel, making the spot even more conspicuous that way. One thing you NEVER want to do is use your finger behind the paper in one spot. You WILL see the mark.



If you are cautious and block it flat using perpindicular /opposite(45 degree angles) passes with a foam block behind it, you can effectively eliminate any wavy visual effects afterwards, while blending down the orange peel and the spot(s) at the same time. It isn`t "easy" per se, but it`s also not hard once you have some time and experience at it.



I learned many years ago, on a black car ( not my T-Bird SC), that spending even a small amount of time on a small spot will reward you with an eye catching indent after it`s buffed out. I had to repaint the panel in fact. Learning the hard way is the best education sometimes.



I have NEVER experienced it again, simply because I learned to always block the surrounding area and feather it out beyond the repaired area. Yes, you will be removing good paint to a degree, but if you`re careful it will be ~ 1/10th of a mil and that`s fine. Let`s face it though-the paint`s already damaged if you`re touching up chips, you have to accept that what you`re attempting is a stopgap between perfection and a repaint, so...even if you`re removing a little bit more of the surrounding paint for it to look correct, it`s the price you must pay in order to not see small indents where you have sanded those touch ups.



Most of the wetsanding results are contingent upon how well you`ve built the touch up, and this too takes practice, in order to allow the least amount of sanding necessary. It`s an art and a skill that takes time.



Just one man`s take, FWIW.



http://members.tccoa.com/onequiksc/resized%20dec%2001%20low%20pro%20side.jpg

[chip douglas]

http://www.web-cars.com/detail/touchup.php

[slvrshadow94tt]

Thanks Guitarman, and as promised..........:bow :bow :bow



For better or worse, this is the type of information and experience I wanted to hear. Is there a special type of foam block that will shape to the contour of the panel when sanding?

I`ve searched the auto supply shops (Pep Boys, Autozone) but can`t find anything.



Also, would it be possible to fix these "craters/dings" by applying a couple of coats of clearcoat touch-up and lightly resanding?

Or do you think I`ll be making a bad situation worse?



Your expertise is appreciated....as well as everyone else who wants to jump in on this :xyxthumbs

[jr weeks]

In answer to the foam/sponge sanding block query( I use the 3M sponge block), I`m surprised you can`t find one locally near you, because Pep Boys, Auto Zone etc. carry them here. But I found this if you want to order online;



http://products3.3m.com/catalog/us/en001/home_leisure/-/node_GSVNG1BLV6gs/root_GST1T4S9TCgv/vroot_GSHCV1ZFXKge/bgel_JSN7S4K1BTbl/gvel_GSGM3WPQTLgl/theme_us_homeleisure_3_0/command_AbcPageHandler/output_html



They are only around $3-4.

They pads/blocks are abrasive (in various grits ) themselves, however, I primarily use them as a backing pad for color sanding. Just wrap the paper around them, making sure you fold the side edges of the paper over itself so there aren`t any factory edges of the sandpaper showing on the bottom/sides of the block. If you don`t do this, the factory edges will gouge into the paint while sanding and cause deep scratches , sometimes impossible to remove.



On the question regarding adding some clear to the touched up areas. Well, generally no, but it depends on how bad the depressions are, how you approach it and what you use, and how good you are. Firstly, shaker cans (the kind you buy in parts stores) of clear are almost always uncatalyzed (no harderner) lacquer based paints. You can`t spray lacquer over enamel (which almost all oem finishes are) without the possibility of a chemical reaction, i.e. lifting, wrinkling etc. So remember that before you think you want to spray some Dupli-Color clear over your oem paint without using an acrylic sealer first. If you ever buy shaker cans of touch up paint, look for enamel only. They will still be uncatalyzed though-so they will forever be air drying (dry to touch, but not chemically), and not very durable.



Now, if you bought a pint of clear urethane enamel and activator, and had a compressor and spray gun, and wet sanded the area with ~800 grit till it was leveled better, you might still see the depressions unless you were really effective at blocking it flat prior, and that would be risky since to do it , you might wind up going through to the basecoat in spots to really flatten it out. It`s tricky and difficult to say, because painters always spray a "guide coat" then block sand with a rigid rubber block, so they can see where the depressions are, then work the area some more till they are certain it`s flat. Just spraying over the existing depressions with more clear isn`t the best approach because-the new clear will just follow the same surface patterns that exist. Now, if you sprayed enough coats of clear, and could block it down flat, you might solve them if they weren`t that deep.



Sorry this is long, but it`s a complicated process and differing variables always enter into how you do it.



If you were to take it to a shop, they would likely block the whole area flat with ~320-400 grit, blend in color to only that affected area, then wetsand the entire panel with ~800 and clear the entire panel. That`s how it`s generally done.



It IS amazing though, that ~3/10 to 5/10 of a mil of paint removed in one spot can be so visually obvious to the surrounding area. The total amount of clear on your car is the width of a baby`s hair (~50 microns or ~2 MILS), and we`re only talking about 1/4th of that or less in these cases where a bit has been sanded down. Amazing indeed.

[chip douglas]

Hello there Guitarman, may i ask what you mean by folding the factory edges ? I have in mind 3M`s 2000-3000 grit sanding strips, but don`t see any edges though.....maybe you simply mean that one has to fold both the right and left side of the strip before using it, that s the only thing i can see at present.......but maybe something slips me ? :o





Oh by the way, i have been to couple of paintshop and they refuse to touch up the fron end of my hood (it s got a few chips, but really small ones though) they say they have to repaint the hole panel.....it s either they know their stuff and know for a fact that they wont be able to match those chip repairs to the surrounding paint, or they just feel lazy and prefer to go to the less complicated solution..........im sure you can help clear this up, since you re in the trade if im correct.



Best regards Guitarman, and by the way your thunderbird is just breathtakingly stunning !:xyxthumbs

[jr weeks]

FWIW, I`m a pro detailer not a pro painter, but my personal background is in restoring /fixing cars and trucks, and painting them myself on many occasions( My t-Bird SC for instance). I have painted in the neighborhood of ~13 whole vehicles, some of show quality, and been around body shops and the people that work in them, most of my adult life. Not an "expert" per se, I sure don`t know everything about every paint and body product and repair, but I do know the basics of painting, blending, and bodywork, and have done all or some to a certain extent.



That said, here`s what I mean on the wet sandpaper;



If you buy the 9inch sheets (full sheets), place the sheet face down (abrasive side down) and put the sponge block on it so that you have about 1/2 inch to 1 inch of sandpaper on EACH side of the block. In other words, if the sponge block is 3 " wide, cut the sandpaper to about4 inches wide, then FOLD those edges on the side of the block up UNDER the block. Now you have a rolled sandpaper EDGE where the side of the block hits the paint surface, instead of the factory sandpaper edge. Just think of it like this; If your hand can get a paper cut from the side of the sandpaper with just the bare factory edge, SO CAN your paint. You want to have a folded over edge(more rounded) along there.



Even if you buy wet sandpaper in the pre-cut 3 3/4 inch wide size (the solo sheets designed for rubber or sponge blocks ) you will need to fold the side edges over themselves and under the block.



Trust me, you WILL freak when you see the side cuts /scratches you put into your paint from a factory paper edge.



Make sense? Let me know if I`ve explained it properly, because it isn`t always easy to get across with text.



As far as your hood and the paint shop, well, if it`s a clearcoat on there , they will have to repaint the entire hood even if they blend in new color to that one area, it`s just a question of whether they will scuff the entire hood, respray the basecoat over the whole thing, and reclear the whole thing OR , sand the chipped area, blend base color ONLY in that spot, and then reclear the entire hood. Either way, they WILL have to spray clear over the whole thing. It`s probably just easier and less of a hassle for them to do the entire basecoat/clearcoat thing than to spot blend it and reclear. Every shop is different, and it all comes down to time = $$$ and what they percieve as being easier for them. Be aware though, if it`s a metallic or pearlescent basecoat/ midcoat, and they just reshoot the entire hood with color, it *MAY* not match the fenders etc. This is why, I would probably try to BLEND the base in that one spot out onto the rest of the hood then reclear the panel. That way, your color match is blending in with the hood itself, and not up against the fenders, where, if it`s slightly off in tone, you will surely see it obviously.



Hope this helps. Best of luck.