Wetsanding through the clearcoat - how long

[swamper8]

I know this is an almost impossible question to answer but exactly how much sanding/effort is required to sand through the clearcoat? Here is my situation:

Car: 2005 Nissan Altima - Super Black

The body is basically trashed. I started out using a 8207(?) Meg foam pad, Ultimate compound and my G110. That didn't touch the damage. Then I moved to a smaller 3-4" LC cutting pad and some M105 compound. That still really didn't do much. I then stepped it up and went to wet sanding. I decided to start my wetsanding on the truck lid, just in case I mess it up I can always buy a new trunk lid and bolt it on. (can't bolt on a new roof!)

So I got some Meguiars 1500, 2000, 2500, 3000 paper and soaked it over night. I used a squirt bottle with some soapy water and wetsanded the top of the trunk with 1500 grit.(used Meg's backing pad) After some time I worked through the orange peel. I knew that part was going to look mint when buffed out. After wetsanding/squeegying for like 10 minutes I could still see marks/scratches in the lid. Even though I know I didn't get all the marks out, I moved to 2500 and did the whole lid. Just for kicks I buffed it out with the M105 and my G110. All the parts of the lid that didn't have scratches came out almost like a mirror. But the rest was just shiny scratches.

Went over the whole lid again with 1500, and again with 2500. Thought it looked better this time (after sanding) so I did the cutting pad/M105 and then yellow pad/swirlX after that. Still looks like dog ****. I can still see scratches. Not swirls, like from the buffer, but straight scratches.

I don't know if my trunk (and maybe other parts of the car) are just too damaged to save or if I need to step up to a rotary buffer, 7207 pad and M105? Maybe even a wool pad, I don't know. At some point I will probably sand right through the clear, I just don't know how close I am to doing that.
I just pretty much hate the car right now, I don't think the person who had it before me waxed it even once in its life.

[Maserati Mario]

Re: Wetsanding through the clearcoat - how long

I've only use a wool pad and 105 on a rotary to remove sanding scratches.
That's what I was taught and it works for me.
It is impossible to tell how much CC is on your paint.
When sanding you have to be careful and do the minimum.
Unless you knew the thickness of the actually base coat and then measured the CC you'll never know.

[Bounty]

Re: Wetsanding through the clearcoat - how long

I know this is an almost impossible question to answer but exactly how much sanding/effort is required to sand through the clearcoat?

Unfortunately not much...

[swamper8]

Re: Wetsanding through the clearcoat - how long

Well I'm going to buy a wool pad and a rotary tonight. Perhaps my G110 just won't cut it so to speak.

[Markus Kleis]

Re: Wetsanding through the clearcoat - how long

Did you sand in straight lines? Sounds like you are seeing the sanding marks you created.

If you do not have experience with a rotary buffer than your other options are: leave it as-is, continue working M105 with the G110, or work small areas with M105 and a terry towel or pad by hand.

Unfortunately, factory finishes vary greatly, but usually allow for extremely limited wet sanding in the clear coat. I would say you are on the edge of burning through already with 2 sessions of wet sanding and buffing it out- but again it is impossible to know without a $1,000+ PTG.

[Michael Stoops]

Re: Wetsanding through the clearcoat - how long

So it sounds like you've done the following, if I'm following you right:

Wet sand w/1500 for several minutes, followed with 2500 and then buffed with M105 on the G110. This removed the orange peel but you still have some deeper scratches. Not sanding marks, but scratches that existed prior to starting this process, right? You got out the orange peel and the sanding marks, and the paint looks fantastic, but the deep scratches are still there.

So you redid the whole process and that further reduced the appearance of the scratches. Right?

If that pretty well sums it up, you probably want to stop there. You've gotten pretty darn aggressive here, by your own admission the paint is "basically trashed", and sometimes scratches and other defects are just too deep to correct with anything short of a repaint. Your repeated sanding operations have likely taken a heck of a lot of clear off. Just the fact you took out all the orange peel in a factory paint job tells us you've removed a lot of clear. Stopping now is probably wise.

Of course, you also mentioned the possibility of replacing the trunk if you go too far. And you want to pick up a rotary buffer. If you don't mind shelling out for a replacement trunk lid, this could be an excellent time to learn proper rotary use. Just make sure to tape off the adjacent 1/4 panel edges so that you don't burn an edge on those..... hard to replace a 1/4 panel.

[swamper8]

Re: Wetsanding through the clearcoat - how long

So it sounds like you've done the following, if I'm following you right:

Wet sand w/1500 for several minutes, followed with 2500 and then buffed with M105 on the G110. This removed the orange peel but you still have some deeper scratches. Not sanding marks, but scratches that existed prior to starting this process, right? You got out the orange peel and the sanding marks, and the paint looks fantastic, but the deep scratches are still there.

So you redid the whole process and that further reduced the appearance of the scratches. Right?

Yes that sums it up 100%, I couldn't have re-described it better. I was afraid that some of the scratches were just going to be too deep to ever get out. Stinks to be me I guess. I did start on the trunk lid and yesterday I did buy a Makita 9227. I have a un-used Burgandy (7207?) Meg's pad. I had to order the proper backing plate which should be in today. So, I am going to go over the trunk lid with the Makita/7207/M105 combo and consider that as good as it's going to get. (without a re-paint of course)

I just hope the rest of the scratches on the car come out better than the ones on the trunk lid. Rear quarters, front fenders and hood look decent. Have some decent marks on the roof that worry me. Can't bolt on a different roof I take it from your reply that if I've cut fully through the factory orange peel than I've removed a decent amount of clearcoat? And beyond that I need to be careful. Good to know.

Once I rotary with the above combo, which of the following should I follow up with? I have the following supplies:

Fresh 8207 and 9207 Meg's pads

M105, SwirlX (big container), ScratchX (small container), G110 and Makita rotary.

After the Makita/7207/M105 I was thinking of going to my G110, 8207 pad and swirlX to finish up.

How does that sound?

[swamper8]

Re: Wetsanding through the clearcoat - how long

Did you sand in straight lines? Sounds like you are seeing the sanding marks you created.

If you do not have experience with a rotary buffer than your other options are: leave it as-is, continue working M105 with the G110, or work small areas with M105 and a terry towel or pad by hand.

Unfortunately, factory finishes vary greatly, but usually allow for extremely limited wet sanding in the clear coat. I would say you are on the edge of burning through already with 2 sessions of wet sanding and buffing it out- but again it is impossible to know without a $1,000+ PTG.

Yes I am sanding in straight lines. I have watched videos on the internet and seen people doing it both ways (circular and straight) Which way is correct? The theory I've read/saw in videos supporting staight lines is that if you sand circular, that's the same motion that your rotary/DA will make and it will be harder for it to remove the sanding scratches.......but I'll take first hand advice over a youtube video anyday

[Michael Stoops]

Re: Wetsanding through the clearcoat - how long

Once I rotary with the above combo, which of the following should I follow up with? I have the following supplies:

Fresh 8207 and 9207 Meg's pads

M105, SwirlX (big container), ScratchX (small container), G110 and Makita rotary.

After the Makita/7207/M105 I was thinking of going to my G110, 8207 pad and swirlX to finish up.

How does that sound?

That should do a very good job for you. But since this sounds like your first foray into rotary buffing, be prepared for a very different experience than D/A buffing. The W7202 cutting pad can generate quite a bit of heat, even at 1500rpm, and you can very quickly go through an edge, trim, etc. Very quickly. Don't blink.

Approach this gently to start - make sure to tape off edges of body panels, stay below 1500rpm to start, keep the pad as flat as possible, don't sweep the buffer back and forth; move it slowly but don't dwell on a given area for any length of time. At first you'll want to very regularly check surface temp by placing your bare hand on the paint where you just buffed. If it's warm to the touch and you don't yank your hand back suddenly, you're doing fine. If the heat is such that you reflexively jerk away, move on to another area. If it feels like you might be able to fry an egg on the panel, put the machine down and take a break. Don't fear the rotary, but definitely respect it.

Keep in mind, however, that if you've wet sanded a couple of times and subsequently removed those sanding marks to your satisfaction with the G110, then you may not get a whole lot further with the rotary. As has been noted already, those deeper scratches that remain following a couple rounds of wet sanding and buffing are likely just too darn deep to safely remove. You have already removed a lot of clear coat and are potentially getting into some dangerous waters here.

[swamper8]

Re: Wetsanding through the clearcoat - how long

Ok thanks. I definitely have to be careful with the rotary. I watched the 5 meguiar's wetsanding/rotary videos on youtube, so hopefully I don't screw up. I only want to use the rotary/7207 on my trunk because I think there are some light scratches that the DA couldn't get out but something slightly more aggressive could. I'm not sure if I just missed these during wetsanding or if I caused them some other way. (laying my tools/bottles down on the trunk lid etc) There are definitely a few scratches which are going to have to stay. I suppose I will find out! Thanks for the tips

[Markus Kleis]

Re: Wetsanding through the clearcoat - how long

Yes I am sanding in straight lines. I have watched videos on the internet and seen people doing it both ways (circular and straight) Which way is correct? The theory I've read/saw in videos supporting staight lines is that if you sand circular, that's the same motion that your rotary/DA will make and it will be harder for it to remove the sanding scratches.......but I'll take first hand advice over a youtube video anyday

Ideally you want to hold the sanding block slightly angled (this is fairly hard to describe without physically demonstrating it) and then use straight motions while holding the sanding block at an angle.

But, the reason I asked is that it is more common to find circular scratches and swirls than straight lines, and I was hinting at the fact that you have still be seeing tracers left behind from the sanding (both straight motions).

It's quite hard to tell for sure though since you did the whole vehicle rather than a test spot.

[swamper8]

Re: Wetsanding through the clearcoat - how long

Well all i can say is holy shnikies!! The top of my trunk is pretty much a lost cause so-to-speak, the scratches are too deep. But I decided to work on the vertical part of the trunk. This portion was in far better condition to start with than the top. I wetsanded with 1500 and 2000, then went at it with my new Makita, a 7207 burgandy pad and the M105. Man that combo is like GOLD! I worked one side for a while, maybe 15 minutes, and it's like a mirror! I honestly don't see a need to do anything else than wax it....am i crazy? I see no swirl marks, either in the daylight or moonlight. Maybe I should just go over it quick with the 9206 pad/swirlX, but I'd prefer to save myself some time, I have a big car to finish.
So I wound up around 900-1000RPM for the whole job. I was super concerned about burning through so i kept the speed down. Will keeping the speed down prevent me from removing defects or will the same defects be removed and just take longer at slower RPM's? I much prefered a slow RPM and applying a little pressure instead of higher RPM's and just the weight of the buffer.

[Michael Stoops]

Re: Wetsanding through the clearcoat - how long

Well done! It's not a big shock that the trunk lid has been taken about as far as you can take it - your previous description pretty thoroughly painted that picture for us. Otherwise it sounds as though you're taking to the rotary like a duck to water! Still, use caution with the W7207 cutting pad - tape off any plastic and vinyl trim that you may come in contact with. Even at 1,000 rpm that pad will do damage to trim in a matter of seconds, and we have a tendency to look at the area we're buffing and not at the lower section of the pad and what it may be contacting. Just a quick touch on trim can mar it significantly.

Using lower speeds can still remove a lot of defects, although it may be a bit light for sanding mark removal. For typical defects such as swirls, fine scratches and some light etching, you should be able to achieve the desired result at those slower speeds. Better to start easy and work into it than spin that machine at full speed in an attempt to save time. That's usually a shortcut to disaster rather than results. Just continue to take your time, and pay attention.

[switerajaya]

Re: Wetsanding through the clearcoat - how long

That should do a very good job for you. But since this sounds like your first foray into rotary buffing, be prepared for a very different experience than D/A buffing. The W7202 cutting pad can generate quite a bit of heat, even at 1500rpm, and you can very quickly go through an edge, trim, etc. Very quickly. Don't blink.

Approach this gently to start - make sure to tape off edges of body panels, stay below 1500rpm to start, keep the pad as flat as possible, don't sweep the buffer back and forth; move it slowly but don't dwell on a given area for any length of time. At first you'll want to very regularly check surface temp by placing your bare hand on the paint where you just buffed. If it's warm to the touch and you don't yank your hand back suddenly, you're doing fine. If the heat is such that you reflexively jerk away, move on to another area. If it feels like you might be able to fry an egg on the panel, put the machine down and take a break. Don't fear the rotary, but definitely respect it.

Keep in mind, however, that if you've wet sanded a couple of times and subsequently removed those sanding marks to your satisfaction with the G110, then you may not get a whole lot further with the rotary. As has been noted already, those deeper scratches that remain following a couple rounds of wet sanding and buffing are likely just too darn deep to safely remove. You have already removed a lot of clear coat and are potentially getting into some dangerous waters here.

Wish I've read this before I was playing with rotary for the 1st time. while working on my hood, I've buffed on the washer nozzle, perhaps 1 second contact time between the foam and the washer nozzle, and the nozzle melt. Also I burn an edge at my hood and the rear quarter panel's edge due to my laziness to tape properly and not realizing that i was really tired at that time (working till 10 o'clock at night and still can't resist the temptation to try to buff the car after get home). But after careful touch up, it's not easy to tell which edge that has been burned. I've never tried to use a DA till date, and perhaps I won't since i don't own a da. I think i love the rotaries better (more powerful but need to be careful), but time will tell.