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  #21  
Old 07-28-2010, 07:25 PM
Garland Edwards Garland Edwards is offline
 
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Dan,
How long do you let the paint cure before starting this process?
Ed
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  #22  
Old 07-28-2010, 10:07 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by Garland Edwards View Post
Dan,
How long do you let the paint cure before starting this process?
Ed
Depends on the paint I guess. The data sheet for DCU2021 clear says 12 hours at 70F before polish.

Sprayed primer and base Saturday and clear Sunday morning. Started cutting Tuesday morning. Only cutting the tops of the wings so I'm already done sanding. Planning to buff top and bottom Saturday morning and haul them to the airport in the afternoon.
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Last edited by DanH : 07-28-2010 at 10:56 PM.
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  #23  
Old 07-29-2010, 07:33 AM
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Dan, did you paint parts as you completed them, or did you wait as long as possible to keep the paint batch the same for everything?
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  #24  
Old 07-29-2010, 08:55 AM
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Originally Posted by mculver View Post
Dan, did you paint parts as you completed them, or did you wait as long as possible to keep the paint batch the same for everything?
I suppose there is some small risk of mismatch when you purchase paint at different times. For me it is outweighed by practical considerations. On the flip side, my new shop is set up to paint pretty much any time I wish, which is not true for all. My old shop was not and I did things different then.

Every builder's situation is different. Do what you gotta do.
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  #25  
Old 07-30-2010, 05:21 PM
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So far I've only written of 3M's 1500 grit purple Trizact discs, mostly because I don't want first-time folks to get into trouble. 1500 cuts fairly slow and if you're only going to buy one kind of disc it is what you want. You can remove heavy orange peel with 1500, but it takes time and a few extra discs. If you have a lot of cutting to do (and you're bold), make your first cuts with a 3M finishing film disc in 800 or 1000 grit, using the same Hookit sander pad and foam interface pad as the Trizact discs:

Yeah, they only come in boxes of 100, but if your paint job is a mess it's cheaper and faster than starting over. For that matter, if you must sand for a repaint these are the hot ticket. You can cut clear quite heavily if necessary and respray more clear directly over an 800 grit scratch.
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Last edited by DanH : 06-11-2018 at 12:02 PM.
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  #26  
Old 07-31-2010, 08:14 PM
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Onward to buffing. Tattoo these three basic details on the inside of your eyelids:

(1) If the pad is held really flat the buffer will be hard to control, in particular on a wavy surface like our RV sheetmetal. You want to tip it just slightly. When tipped it will pull or push in your hands in some particular direction; that's how you steer the thing without wearing yourself out. The pad rotates clockwise, so if you tip right the buffer will pull away from you, tip left and it will push back toward you, tip away and it will go left, etc.

(2) When near an edge the pad must buff off the edge, not onto the edge. Tip the buffer as necessary so the pad contact moves off the panel. If the contact is moving onto the panel it will cut through the paint on the edge very, very quickly.

(3) Just like with the sander, it is important to work in tidy overlapping patterns, so as to cut evenly everywhere. No random motion please.

A few practical points.

To apply compound, squirt a generous line across the panel, then roll the pad along the line like so....



....which will put the compound in the waffles under the pad just like magic. Slide the pad around a bit to distribute any excess compound, and only then pull the trigger and start buffing. Do not pull the trigger on the buffer and stick it in the compound, as you will instantly distribute the compound on the walls, the front of your shirt, etc.

Loop the cord over your arm. It is important to not contaminate the pad with dirt, so you don't want the cord flopping around on the surface and serving as a dirt transfer device.



Always move in an even pattern with consistent speed. Pay attention to the rotation direction of the contact patch when you get near an edge. Remember, always buff off the edge, not onto the edge, or run the pad so the contact is moving parallel to the edge. I can't stress this detail enough. It's not just a matter of cutting through the paint. If you let the pad's contact patch rotate into an edge and the pad hooks on the edge or a corner, you may even bend metal.



From time to time you should "spur" the pad. The name comes from the official tool for this job, which really does look like somebody attached a handle to a stack of stars taken from old cowboy spurs. The points of the stars lift and fluff a wool pad and remove all the built up (and worn out) compound. You don't need a spur tool for a foam pad. Just hold an ordinary paint stick against the rotating pad and it will throw off the old compound quite nicely.

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Last edited by DanH : 06-11-2018 at 06:25 AM.
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  #27  
Old 08-03-2010, 05:23 PM
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More random details.

The 6085 and 6064 compounds are water soluble. Still have that water bucket handy, right? The easy way to clean a panel after compounding is to wipe it down with a sopping wet rag followed by a dry rag. Take a good look at the surface and compound again if necessary. After the machine polish step (6064) we usually just wash a car with soap and water to clear away all the compounds.

Buffer pads tend to wear more near the edge than the middle, a matter of velocity. Don't throw them away. Instead cut them down and stick them to your sander for use on small parts:



It's a little slower than a buffer, but you can work alone. The buffer will throw small parts across the room unless you have a helper to hold them tightly.

Buffers also throw compound. There's no way to prevent it, so cover adjacent surfaces and tools with a drop cloth, or work in a dedicated space, or move outside on the lawn.

To clean wax and compound out of cracks and crevices, take an ordinary 1" paintbrush and cut the bristles down to about 1/2" long. Let the wax dry, then just brush it out of the cracks.

I use paper towels during all the paint steps, but switch to cotton rag for all the cut and polish work.....big boxes of cast-off, laundered hotel washcloths and towels are usually less than $1 p/lb. The trick is finding your local rag guy.

Runs in the top coat can be fixed. Runs in the primer or base coats must be removed before spraying the next coat. If you try to cut topcoat over a primer or basecoat run you will cut through almost instantly.

Likewise, if you spray primer or base and get bad orange peel, spraying topcoat on it will not improve anything. Stop, sand it down, spray the primer or base again, then continue.

Don't make yourself crazy! You can see surface detail in the shop under good tube lighting which is unlikely to be seen outdoors....try it and see. And go study the factory paint on cars, in particular some high-end cars. You might be surprised about what you spot with your newly trained eye.

I am not a great painter. Thank God for sanders and buffers!



Have fun.
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Last edited by DanH : 06-11-2018 at 06:27 AM.
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  #28  
Old 08-04-2010, 09:19 AM
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Quote:
Originally Posted by DanH View Post

There's another important trick to this tipping stuff. When near an edge the pad must buff off the edge, not onto the edge. In the example below you would tip the buffer away from you so the pad contact was moving off the panel. If the contact is moving onto the panel it will cut through the paint on the edge very, very quickly.
But everyone will do it at least once, just to drive home the lesson! (which is why my HS has the best looking paint on the whole plane. (Got to do it twice))
Never daydream while running a buffer.
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  #29  
Old 08-02-2011, 06:41 AM
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rph142 rph142 is offline
 
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Awesome thread! I just bought a load of compound, polish, sanding discs, pads, etc to help clean up my botched elevators. I shot what I thought was my best work yet last night. This morning I went out and found what looks like solvent pop or overspray hazing along with orange peel scattered throughout. I will be buffing stewart systems poly base coat, which seems to be uncharted territory. Ill post the results when Im finished. Thanks for the tips!
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  #30  
Old 08-02-2011, 09:35 PM
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MrNomad MrNomad is offline
 
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Thumbs up Great job Dan!!

Great work Dan. I tried to use a razor once with less than perfect results so I stick with 1200, 1500 and 2000 grit. It goes slower but I get the desired result.

Here's what happens when u operate the buffer too fast. Talk about a heart breaker on an otherwise perfect 68 Corvette!



This post is a MUST READ for anyone thinking of painting & my suggestion is to practice on expendable parts. Intentionally create runs so you can practice fixing them.

Ditto on single stage metallic. Get it right the first time or switch to base coat clear coat which you can fix.

Thanks Dan.
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