Cut and Buff Plans

S

ssanto

How long after laying SPI Universal should I wait to cut and buff? I shot the body on Sunday and the fenders on Tuesday. I was planning to start cutting on Friday. Is that an appropriate time frame?

I put four coats of Universal on, but I think I did it too lightly. I was probably moving a little too fast (afraid of runs) and didn't overlap my passes by 50%.. It was more like an overlap of 20% or even a little less. So perhaps my four coats is more like 2 coats. The car has pretty heavy orange peel throughout. I was using my Devilbiss 670 Plus gun with a 1.4 tip and 40 PSI at the gun.

Here is what I was planning on doing:
- Cut with 1500 using 3M No. 20 Wet-or-Dry sponge pad
- Sand with 2000 using 3M No. 20 Wet-or-Dry sponge pad
- Polish with Meguiars 100 and "medium-heavy" cutting pad on rotary polisher
- Polish with Meguairs 205 and "light-medium" polishing pad on rotary polisher

Does that sound about right? Should I start cutting with a heavier grit? I also have a Hutchins 4500 DA sander that I could use.


Thanks,
Sal
 
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Your best bet would be to do a small area with the system that you plan on using. When you say heavy orange peel, do you mean dry spray like the droplets are not connected, or like the surface of a golf ball? With that little amount of overlap I would guess it is dry spray. Try a small area and if it does not look like you want, start with 1200, then 1500, then 2000. Try not to get any more aggressive than necessary.
 
Does it matter if I wait another week or two to start? I'm going out of town on the 4th-11th and it might be better if I waited until I got back...
 
texasking said:
Your best bet would be to do a small area with the system that you plan on using. When you say heavy orange peel, do you mean dry spray like the droplets are not connected, or like the surface of a golf ball? With that little amount of overlap I would guess it is dry spray. Try a small area and if it does not look like you want, start with 1200, then 1500, then 2000. Try not to get any more aggressive than necessary.
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I think I have a mix of both depending on the area... and some dust nibs.
 
You can wait as long as you want, will still buff great. I would probably start with 1200. If you mean a foam pad like an orange CG pad, you may have to finish with a finer grit like 3000. Just try a small area at a time and see if you like the results.
 
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texasking said:
You can wait as long as you want, will still buff great. I would probably start with 1200. If you mean a foam pad like an orange CG pad, you may have to finish with a finer grit like 3000. Just try a small area at a time and see if you like the results.
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Yes it is the orange CG pad. Should I start with a wool pad to have more cutting when I start on the rotary?
 
The wool pad cuts much faster and will not require you to finish with as fine a grit. I like the orange pad, but as a second step, unless you finish with 3000 or finer.
 
I would do a small area, say 12" square, and see how your process works, then fine tune from there. A wool or hyrbrid wool/foam pad would be the way to start compounding after sanding.
 
dhutton01 said:
If you only have two coats of clear with heavy peel you are headed for a heartbreak imho. Sand and apply two more coats.

Don
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I went and looked at the car again and at my test panel. The spray pattern on the test panel is about 10 inches tall. On the car, the top of the door to the rocker is about 28 inches. I replayed my painting and I had 5 passes on that part of the car.... and when I draw that out on paper, it gives me about 50% overlap. The centerline of each pass is about 5-6 inches apart.

I also replayed my painting and I think my speed may have been a little faster than 1 foot per second. I would do a 10 foot pass in about 8.5 seconds.

So maybe I'm not as far off on the coverage as I thought...
 
dhutton01 said:
If you only have two coats of clear with heavy peel you are headed for a heartbreak imho. Sand and apply two more coats.

Don
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I agree with Don. Nothing more discouraging than to almost have it buffed out and go thru somewhere. Or to have buffed the clear too thin. If I know I'm going to sand and buff I always put 3 coats. I've sanded and buffed thru alot having only put 2 coats so I try to prevent it when I can.
 
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I've been practicing on a test panel I shot with base and clear a few weeks ago...

On the flat area, I spent a minute or so rubbing an 8" x 8" area with 1000 and a soft pad and didn't break through the clear. And then I switched to a hard block and did another minute with 1000. It finally broke through and immediately went all the way through the base and into the primer. I had expected that I would see when I broke through the clear and stop before I get through the base, but it didn't seem to work that way.

On a hard edge, it was much easier to break through the clear and base... but I still had to really try to intentionally do it with the soft block.
 
I figure I'd give cut and buff a shot as it is. If it works, then I avoid another trip into the paint booth. If it doesn't, then I'd just spot shoot the base in the spots that burned through and then re-clear it. So it seems like nothing would be lost by trying to cut and buff it first... other than some time wasted by cutting and buffing areas that would end up being re-cleared.
 
I'm new at this myself, having painted my first car recently. You have been advised that you don't have enough clear for a cut and buff, by guys who know what they are talking about through experience. In my opinion, for what it's worth, is that you will end up making a serious mess out of this paint job if you cut and buff at this time. Sand it and shoot more clear, as advised. Believe me, cut and buff is time consuming and labor intensive, and you don't really want to have to do it twice. Your car, your time, your money.
 
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