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Another great day spent introducing people to the concepts of wet sanding and rotary polishing.
We start with some hand sanding, having allowed the sand paper to soak in water for at least 15 minutes prior to use (the sand paper will curl up when it's ready to go). In this image we've actually got the paper wrapped around the E7200 hand pad incorrectly - there is a section of the sand paper wrapped only partially under the surface contacting the paint (visible at the bottom of the pad). This will result in uneven sanding, so make sure you properly wrap the sandpaper around the pad so that the overlap is at the top, not where the abrasive meets the paint.
When hand sanding you want plenty of water to flush out any paint residue and abrasive particulate that might dislodge from the paper/film backing. Strokes should be 6" - 8" in length with a very tight overlap. Looking at the stroke marks below you should be able to determine that the paper is moved at an angle relative to the shape of the pad. This prevents the edges of the pad from digging into the paint and creating deeper marks in the paint.
The fully sanded section, here after 2000 grit, should be uniformly covered, dull, flat, however you want to describe it.
This is what happens when you don't control your sanding motions and just randomly have at it. It's not only ugly, it's inconsistent and will present difficulty with buff out, and of course the final product won't be uniform. That's just lose-lose-lose.
The white material on the face of the sand paper is clear coat residue. It needs to be regularly flooded off with water to keep the work area as clean as possible.
The E7200 pad is very flexible - make use of that to help you when working on contours like we are on the curved features of this hood.
It may be a bit tricky to see in this image, but the left side of this sanded area is where the hood contours - you can also see the light reflections right where the sanding marks stop on the left side. That's where the contour rolls up and then flattens out again. Working with a slightly rolled pad we are able to sand into this contour without compromising the paint on the edge.
From a different angle, this is the same area. On the right side is the area shown in the image above, but on the left side you see what looks like two separate sanded areas. In fact, those two areas were done at the same time by working the length of the E7200 pad across the contour. The reflections in the paint show the contour pretty well, as the curvature of the reflection matches the contour. And you can then see that the sanded areas match the straight areas of the reflections, ie the flat areas surrounding the contour. And the sandpaper effectively bridged across the shallow of the contour, totally missing the paint. While that's bad enough, what's worse is that the high edge of the contour (the lower portion) was getting hit pretty darn hard and you run the very real risk of sanding right through the clear. In fact, later in the day, one of our students did that very thing.
Sanding by hand will very quickly show you even the slightest contours, like this very light contour toward the edge. Sanding in a back and forth movement perpendicular to the edge rather than parallel to it reveals the contour: At the fingertip you can see the paint is fully sanded in a line parallel to the edge, but everything else has that mottled look that is telling you you're only touching the tops of the orange peel. That means you're pretty well hammering that edge but hardly touching the surrounding paint. Time take another approach.
Sanding parallel to the edge, using your thumb as a guide so you don't sand fully over the edge. Remember, the paint is thin on edges, so sanding means removing precious material, and you still have to buff it out. Which is hard to do on an edge anyway.
Again, on the left side you can see the sanding marks running perpendicular to the edge, and the lack of uniformity created by the subtle contour present. On the right side is the result of attacking the area in two different ways: edge work as shown above for the flat area on the edge, and rolling into the contour as previously described. The end result is a nice, uniform sanded area.
DA sanding changes things up a bit as we have both finishing discs (left side) and sanding discs (right side) available to us.
DA sanding movements are just like those used when DA polishing, just make sure to back way off on the pressure!
This is more of a "damp sanding" process than true wet sanding - we aren't soaking the discs in water prior to use, nor are we flooding the work area with water. But we're obviously still pulling up clear coat residue so we need to keep things clean all the time.
Don't fear the rotary, but respect it. It's not hard to control if you don't fight it.
Time to cut the guys loose and let them try their hand at hand sanding, DA sanding and rotary polishing.
Working the contour with a rolled E7200 hand pad.
4" polishing pad on the rotary.
This is what can happen with a foam cutting pad when you aren't paying attention; burned paint. Hey, better in our training garage than on someone's pricey car.
Rotary on the edge.... just pay attention to the rotation of the pad and make sure the pad is rotating off the panel and not climbing up onto the panel. Adjust a bit of tilt to the tool to handle this.
Left side hand sanded with 2000 grit, right side subsequently done with 3000 grit on the DA. Notice the gain in gloss and reflectivity after the 3000 grit sanding.
Team buffing!
The whole gang at work.
It's like a mirror!!
We start with some hand sanding, having allowed the sand paper to soak in water for at least 15 minutes prior to use (the sand paper will curl up when it's ready to go). In this image we've actually got the paper wrapped around the E7200 hand pad incorrectly - there is a section of the sand paper wrapped only partially under the surface contacting the paint (visible at the bottom of the pad). This will result in uneven sanding, so make sure you properly wrap the sandpaper around the pad so that the overlap is at the top, not where the abrasive meets the paint.
When hand sanding you want plenty of water to flush out any paint residue and abrasive particulate that might dislodge from the paper/film backing. Strokes should be 6" - 8" in length with a very tight overlap. Looking at the stroke marks below you should be able to determine that the paper is moved at an angle relative to the shape of the pad. This prevents the edges of the pad from digging into the paint and creating deeper marks in the paint.
The fully sanded section, here after 2000 grit, should be uniformly covered, dull, flat, however you want to describe it.
This is what happens when you don't control your sanding motions and just randomly have at it. It's not only ugly, it's inconsistent and will present difficulty with buff out, and of course the final product won't be uniform. That's just lose-lose-lose.
The white material on the face of the sand paper is clear coat residue. It needs to be regularly flooded off with water to keep the work area as clean as possible.
The E7200 pad is very flexible - make use of that to help you when working on contours like we are on the curved features of this hood.
It may be a bit tricky to see in this image, but the left side of this sanded area is where the hood contours - you can also see the light reflections right where the sanding marks stop on the left side. That's where the contour rolls up and then flattens out again. Working with a slightly rolled pad we are able to sand into this contour without compromising the paint on the edge.
From a different angle, this is the same area. On the right side is the area shown in the image above, but on the left side you see what looks like two separate sanded areas. In fact, those two areas were done at the same time by working the length of the E7200 pad across the contour. The reflections in the paint show the contour pretty well, as the curvature of the reflection matches the contour. And you can then see that the sanded areas match the straight areas of the reflections, ie the flat areas surrounding the contour. And the sandpaper effectively bridged across the shallow of the contour, totally missing the paint. While that's bad enough, what's worse is that the high edge of the contour (the lower portion) was getting hit pretty darn hard and you run the very real risk of sanding right through the clear. In fact, later in the day, one of our students did that very thing.
Sanding by hand will very quickly show you even the slightest contours, like this very light contour toward the edge. Sanding in a back and forth movement perpendicular to the edge rather than parallel to it reveals the contour: At the fingertip you can see the paint is fully sanded in a line parallel to the edge, but everything else has that mottled look that is telling you you're only touching the tops of the orange peel. That means you're pretty well hammering that edge but hardly touching the surrounding paint. Time take another approach.
Sanding parallel to the edge, using your thumb as a guide so you don't sand fully over the edge. Remember, the paint is thin on edges, so sanding means removing precious material, and you still have to buff it out. Which is hard to do on an edge anyway.
Again, on the left side you can see the sanding marks running perpendicular to the edge, and the lack of uniformity created by the subtle contour present. On the right side is the result of attacking the area in two different ways: edge work as shown above for the flat area on the edge, and rolling into the contour as previously described. The end result is a nice, uniform sanded area.
DA sanding changes things up a bit as we have both finishing discs (left side) and sanding discs (right side) available to us.
DA sanding movements are just like those used when DA polishing, just make sure to back way off on the pressure!
This is more of a "damp sanding" process than true wet sanding - we aren't soaking the discs in water prior to use, nor are we flooding the work area with water. But we're obviously still pulling up clear coat residue so we need to keep things clean all the time.
Don't fear the rotary, but respect it. It's not hard to control if you don't fight it.
Time to cut the guys loose and let them try their hand at hand sanding, DA sanding and rotary polishing.
Working the contour with a rolled E7200 hand pad.
4" polishing pad on the rotary.
This is what can happen with a foam cutting pad when you aren't paying attention; burned paint. Hey, better in our training garage than on someone's pricey car.
Rotary on the edge.... just pay attention to the rotation of the pad and make sure the pad is rotating off the panel and not climbing up onto the panel. Adjust a bit of tilt to the tool to handle this.
Left side hand sanded with 2000 grit, right side subsequently done with 3000 grit on the DA. Notice the gain in gloss and reflectivity after the 3000 grit sanding.
Team buffing!
The whole gang at work.
It's like a mirror!!
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