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View Full Version : Pictures from May 9, 2015 Advanced Class



Michael Stoops
May 11th, 2015, 10:02 AM
Saturday's Advanced Class was the first such class where most of the participants were already pretty experienced with the rotary buffer. Wet sanding, however, was still new to them so there was plenty to learn!

As usual, we spent time with both hand sanding and DA sanding, and the differences in technique between them.

Although this picture may say otherwise, this is not a "contest"!
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_2.jpg

As a first go, not bad. But the overlaps could be tighter, which comes with practice.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_1.jpg

Hand sanding in two directions; one for the first cut, the second for the finer cut to take off the tops of the sanding scratches from the first cut. The idea is to refine the surface as much as possible, while taking off the least amount of paint.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_10.jpg

DA sanding; while similar to DA polishing, you don't use anywhere near the level of pressure when doing this. Pad rotation, overlapping strokes, back and forth motions are all the same as used when polishing with a DA.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_8.jpg

Nice uniformity of sanding marks, except for that section in the middle. That's the reflection of the overhead fluorescent lights showing up in the middle of the picture, along with a dirt nib. So why do only see this in the middle? Check the next image below.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_13.jpg

A broader view shows that panel has a slight concave to it so the sanding media was bridging across the lower portion, making only very slight contact with the paint. The mottled appearance is due to only the tops of the texture being sanded, leaving slight reflections emanating from the untouched paint in the low spots.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_12.jpg

A second pass of the same area, using the DA sander from two different angles, removes the texture and evens out the finish. Even very fine, gentle contours can pose issues when sanding.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_11.jpg

Hand sanding into a tighter contour forces you to change things up a bit. The flexible backing pad is curved to better match the radius of the contour. In this situation, a tighter curve on the pad is likely called for, but you can see it's actually lifting off the paint on the side closest to the operator's body. That means the curve of the pad is tighter than the contour being worked on, which is desirable. If the curve of the pad wasn't tight enough, it would bridge over the lower portion of the panel contour and you'd get the same sort of non-uniform sanding shown in the images above.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_9.jpg
Historically we used rotary buffers to remove sanding marks as the DA just wasn't up to the task. Today's technology in both tools, pads and compounds - and even abrasives - is changing the industry dramatically and it's now common to remove those sanding marks with a DA. Here we're using the new MT300 DA buffer, a microfiber Xtra Cut disc, and M100 at 5800 OPM.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_7.jpg

Sand and buff!
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_3.jpg

Revealing the gloss after compounding out the sanding marks!
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_4.jpg

So what kind of results were the guys getting? This is a "before" shot of the recently painted panel, showing a lot of micro texture in the surface.
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_6.jpg

After some sanding (either 1500/2500 by hand or 1500/3000 by DA) and then a bit of compounding and polishing the difference in clarity and gloss is huge!!!
http://archive.meguiarsonline.com/forums/photopost/data/2364/2015-05-09_5.jpg

mohebmhanna
May 12th, 2015, 08:28 AM
Mike,
How it was removing the sanding marks (1500/3000) by using MT300 DA buffer, a microfiber Xtra Cut disc, and M100 at 5800 OPM compared to the rotary buffer in terms of the speed to remove the sanding mark and the gloss. How many passes are applied to remove the sanding marks by MT300. Thanks

Selectchoice
May 12th, 2015, 04:18 PM
Great post! Love the concept of these classes.

davey g-force
May 12th, 2015, 06:31 PM
Yes, awesome post.

Why is it that any time I see or read about DA sanding, an air powered DA is being used?

Are electric DA's not powerful / torquey enough? Or is it to do with using an electric tool in a wet environment? Or some other reason?

I wouldn't think that there is enough water to cause any concern, but not sure...

Detail Werks
May 12th, 2015, 06:53 PM
Is that Mad Marvin I see ?

Selectchoice
May 12th, 2015, 07:08 PM
IMO, safety is a big factor in the reason why air powered DA's are used in these environments. Even a few drops of water can be a concern when it comes to electricity...:grrrr1

I've seen a few write ups where electric DA's are shown, but I think in these general educational environments, "best practice" is to use an air powered device.

Also, I believe electric DA's are generally more powerful than their air powered brothers.

Michael Stoops
May 13th, 2015, 07:21 AM
Mike,
How it was removing the sanding marks (1500/3000) by using MT300 DA buffer, a microfiber Xtra Cut disc, and M100 at 5800 OPM compared to the rotary buffer in terms of the speed to remove the sanding mark and the gloss. How many passes are applied to remove the sanding marks by MT300. Thanks
If you refine your sanding marks down to 3000 on a DA they will usually come out very, very quickly with the MT300, microfiber pad and M100. Heck, even on pretty hard paint I've done 2500 grit hand sanding and pulled those marks super fast with that combo. The changes in this industry in the past 5 years have been really dramatic, and with advent of more powerful DA polishers, microfiber pads and DA compatible compounds like M105/M101/M100 it's pretty amazing what you can do without using a rotary these days. In fact, the extreme majority of high end detailers I talk to rarely use a rotary any longer because of this.

Yes, awesome post.

Why is it that any time I see or read about DA sanding, an air powered DA is being used?

Are electric DA's not powerful / torquey enough? Or is it to do with using an electric tool in a wet environment? Or some other reason?

I wouldn't think that there is enough water to cause any concern, but not sure...
Actually, electric DAs tend to have a lot more power and torque (in fact, waaaaay more torque) than pneumatic DAs do. And when it comes to sanding, you don't want a bunch of torque. Also, as Selectchoice points out, water and electricity rarely mix well (Ben Franklin got lucky!!) so pneumatics are just flat out safer. That said, when using our Unigrit sanding and finishing discs you really aren't "wet sanding" in the truest sense of the word. Wet sanding, when using sand papers, involves a lot of water to keep the surface clear of debris, and the abrasive media is designed around that process. The abrasive dics used when DA sanding are actually a totally different technology and a minimal amount of water is used. For a given work area when DA sanding, you're using just a couple trigger pulls out of a spray bottle onto the surface, and maybe one or two on the abrasive disc. You're really just misting it on so danger is mitigated. Still, you need to be very aware of what you're doing and excercise plenty of caution when DA sanding with an electric tool. It's possible, and quite common actually, but you just need to be aware!


Is that Mad Marvin I see ?Yes indeed! He did great, too!

davey g-force
May 13th, 2015, 11:09 AM
Thanks Mike :xyxthumbs