Wetsanding through the clearcoat - how long

[Mark Kleis]

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]

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]

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]

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.