Planning to Wetsand Touch up Paint

[Pocket_Aces]

Well I found a nasty little chip on the bottom of my door (metallic silver paint). At least its in an inconspicous place. I cleaned the chip out with some Isopropyl and have filled it in with touch up paint. I just put on the last coat yesterday night.

I plan to sand the blob down this coming Friday but I am a little apprehensive about the sanding part. So I have a couple of questions.

1. I have heard that you should sand in one direction and not back and forth. Is this correct?

2. I have the MEGK2000 unigrit block and plan to use that initially. But I also have 2500 and 3000 grit P grade wet/dry silicone carbide sandpaper. Should I use the the sandpaper after the block and do I need to soak the block ahead of time?

3. Is a block eraser good to use as a sanding block for the sandpaper?

4. The chip is longer in one direction so I should be sanding perpendicular to this direction right?

5. When wetsanding is soap and water best to use or just water?

6. I also have a rotary and a PC 7424 with some 3M Finesse-It II. Will the PC and the 3M be sufficient? I definitely don't want to burn the paint since the chip is about 3/4" away from the bottom of the door. In case I do need to use the rotary if I have the door closed up against the lower rock panel I can buff with the rotary and not really worry too much about burning the edge since the rocker panel will be there to support the buffing pad right?

7. Has anyone experienced the touch-up paint pulling out upon sanding or buffing and do you have any suggestions on how to avoid this?

Thanks for the help.

[Markus Kleis]

Re: Planning to Wetsand Touch up Paint

The only question I can answer comfortably is #5- use some soap with your water.

Otherwise, I would be telling you stuff that I am only 90%~ sure about. Sit tight and someone will straighten this out for you.

Mark

[Mike Phillips]

Re: Planning to Wetsand Touch up Paint

Read through all the comments and suggestions in the below threads,

http://meguiarsonline.com/forums/showthread.php?t=25592

http://meguiarsonline.com/forums/showthread.php?t=18836

[Mike Phillips]

Re: Planning to Wetsand Touch up Paint

I plan to sand the blob down this coming Friday but I am a little apprehensive about the sanding part. So I have a couple of questions.

You want the touch-up paint completely dried and hardened before starting.

1. I have heard that you should sand in one direction and not back and forth. Is this correct?

No back and forth is perfectly fine, you just don't want to do anything wacky like sand in circles. (Yes, some people do this and some people recommend this)

2. I have the MEGK2000 Unigrit block and plan to use that initially. But I also have 2500 and 3000 grit P grade wet/dry silicone carbide sandpaper. Should I use the the sandpaper after the block and do I need to soak the block ahead of time?

Yes, soak the block over night.

You can knock the blob down with the block and then to a LITTLE finishing work with sandpaper. If possible, place some painters tape around the blob so that when you sand you don't actually sand on the surrounding good paint.

3. Is a block eraser good to use as a sanding block for the sandpaper?

Something flat, hard and with a little cushion like a sanding backing pad.

4. The chip is longer in one direction so I should be sanding perpendicular to this direction right?

Yes or at a 90% angle to the length of the defect.

5. When wet-sanding is soap and water best to use or just water?

Yes it provides lubrication for smoother sanding.

6. I also have a rotary and a PC 7424 with some 3M Finesse-It II. Will the PC and the 3M be sufficient? I definitely don't want to burn the paint since the chip is about 3/4" away from the bottom of the door. In case I do need to use the rotary if I have the door closed up against the lower rock panel I can buff with the rotary and not really worry too much about burning the edge since the rocker panel will be there to support the buffing pad right?

Usually Porter Cable units don't have enough power to remove sanding marks unless you really know what you're doing and/or use smaller pads than what Meguiar's currently offers. It has to do with the hardness of clear coats and the clutch in the tool that will prevent the pad from rotating if you apply too much pressure to the PC

It would actually be more controlled to do this by hand using our M105 for the reasons I stated in the first link posted in my first reply.

7. Has anyone experienced the touch-up paint pulling out upon sanding or buffing and do you have any suggestions on how to avoid this?

Yes, many times and that's why I included the first link in my first reply. You're trying to do something that's very hard to do really well. How do you avoid simply pulling the touch-up paint out of the chip?

Let the paint dry till it's ROCK HARD and then work carefully by hand with M105 instead of using a rotary buffer which has a tendency to heat up the area and then pull out the touch-up paint.

How does the rest of the car look?

[Pocket_Aces]

Re: Planning to Wetsand Touch up Paint

Thanks Mike for the replies. The rest of the car looks pretty sharp. It's only 5 months old so the rock chip is pretty painful.

Good idea about masking the area around but would this also mean that I wouldn't be able to completely level the touch since the tape's thickness would keep the sanding block a bit off of the surface? I wonder if thin transparent tape would get me close enough.

BTW is the M105 available at PepBoys or Autozone and would the M105 work with the PC? I am a bit hesitant to do things by hand since I really don't have much experience buffing by hand. Also is the M105 the only finishing material I will need and no further polishing?

[Mike Phillips]

Re: Planning to Wetsand Touch up Paint

I wonder if thin transparent tape would get me close enough.

Be careful, painters tape isn't as sticky as transparent tape for a purpose. Transparent tape could pull paint off the car especially around a chip.

BTW is the M105 available at PepBoys or Autozone

No. Those are retail stores for the Consumer Market, you want to find a PBE store that caters to the Professional Market.

We have to sub-forums with tons of information, .
Hot Topics
How To Articles

here's an example from the how-to sub-forum.
How to locate Meguiar's Professional and Detailer products in your hometown

and would the M105 work with the PC?

M105 is formulated and intended for use with either a rotary buffer or by hand. A lot of people have very good luck with it when using it with a DA Polisher like a PC or our G110 but Meguiar's doesn't make any guarantees for your satisfaction when you use it with a PC

I am a bit hesitant to do things by hand since I really don't have much experience buffing by hand. Also is the M105 the only finishing material I will need and no further polishing?

Working by hand isn't that hard, most people work by hand versus a rotary buffer and M105 is amazing by hand.

It leaves a clear, smooth finish but in some applications you may want to do some follow up polishing with a less aggressive product, you could use ScratchX.

Also, after compounding, cleaning or polishing you always want to apply some wax or a paint sealant to protect the paint.

[Pocket_Aces]

Re: Planning to Wetsand Touch up Paint

Good point about the tape but I was thinking about the hazy transparent tape 3M makes. Really comes off pretty easy so I should be fine. I just thought the painters tape which I also have would be a little thick and leave the touch-up paint protruding some but I might try that first then switch if necessary.

Thanks for all the good info.

[Mort Corey]

Re: Planning to Wetsand Touch up Paint

Just to add to Mike's thought of letting the paint cure rock hard.....give it a couple of weeks after your last coat is applied (or even longer depending on your weather conditions and climate). If this is a small chip (say less than 1/4") I think you'll have a better shot at not pulling up the repaired area going by hand vs machine....ask me how I know this

Mort

[Pocket_Aces]

Re: Planning to Wetsand Touch up Paint

Okay I just did all this yesterday. I used the 2000 unigrit block followed up with the 3000 unigrit paper. Both were soaked in water for over 24 hours. I had to remove the tape to actually get the blob all the way smooth as the painters tape and even transparent tape were too thick. What I found really odd is there was hardly any hazing of the paint from the wetsanding. It was still pretty shiny. I went over the area with some M105 by hand first then with some Zymol and a DA using moderate pressure with an orange lake country pad. I noticed that after I was done the blob was actually slightly recessed as the DA probably ate away at it some but not the surround paint. The repair looks pretty much inconspicuous so I am happy with the results. Since it is metallic paint the shade is a bit off but it looks so much better than the blob that was there. Next time I do this I just plan to use the M105 and Zymol both by hand.

I think using a rotary with any amount of force would have recessed it more or pulled it out as others have mentioned.

[Mike Phillips]

Re: Planning to Wetsand Touch up Paint

I think using a rotary with any amount of force would have recessed it more or pulled it out as others have mentioned.

Thanks for the follow-up with your insights from the experience...

We'll tag this with Touch-up Rock-chip