let's talk sanding

Wet sanding and buffing; I am one of the few who loves doing it. I once had almost 80 hours in doing a show car; start with 800 3M and a hard stick of your choice, then 1000/ 1500/2000 meguiars is the only paper i will use other then the 800 3M. All paper soaks in water for 24 hours prior to using in separate pails. I don't want a 800 grit stones getting picked up while i'm using 1000 grit and so on. I also use a couple drops of dish soap in the pail. After i finish with the 800 i switch to a soft block' i am done trying to get it flat. Now i am just trying to get the prier sand scratch's out finely ending up with only 2000 grit scratches to buff out. Some times depending on the color i will use 3M powder guide coat in between each grit change. I tried the DA thing once. for 10 min; i ended up throwing it all in the trash!!!!

I did quite a bit of practicing on a test panel, but not having very good luck with my sanding technique so far. I am using Maguairs paper. I am doing fine at back to a gloss, but I continue to have sanding scratches (really shiny scratches). Perhaps my Univeral Clear isn't cured enough, or my sanding technique isn't right. I am finding the paper has clear stuck to it after just a few strokes. It is about 5 week old universal clear (No UV exposure yet). My car has had a few days in the sun, but not the test panel I'm working on.

1st question, how big of a block should I use? (hard block & soft block)
2nd question, how much pressure? (Hard block steps, soft block step, and Trizact by hand)?
 
I did quite a bit of practicing on a test panel, but not having very good luck with my sanding technique so far. I am using Maguairs paper. I am doing fine at back to a gloss, but I continue to have sanding scratches (really shiny scratches). Perhaps my Univeral Clear isn't cured enough, or my sanding technique isn't right. I am finding the paper has clear stuck to it after just a few strokes. It is about 5 week old universal clear (No UV exposure yet). My car has had a few days in the sun, but not the test panel I'm working on.

1st question, how big of a block should I use? (hard block & soft block)
2nd question, how much pressure? (Hard block steps, soft block step, and Trizact by hand)?

Good Qs. If the paper has clear stuck in it or "gumming up" it has not cured all the way. Get it out in the sun for a few days.
I use a hard block when sanding with 800 I have mostly acrylic hard blocks in various shapes and sizes depending on the shape of the panel you are working on. Sanding technique...always criss-crossing . After i feel like the panel is flat enough i switch to a 3m black firm sponge pad to finnish up through the various grits.
Medium pressure from start to finnish all by hand with water Also if you are pushing to hard it will leave deep scratches You can also use 3M guide coat in between the grits. Hope that helps
 
Did a bit of sanding today with a couple of new products from the Buflex line, it’s their new Blue K-2500 disc and also their dedicated Buflex interface pad.

Also the first time I ever use the Yellow sanding disc in 2000 grit. I worked on a tailgate sprayed with Universal clear that sat about 12hrs, overnight. The clear was a little soft but still sanded fine with the 2000.

After the 2000 I used the Buflex blue and proceeded with the buffing. It was solid white PW7 so no need step it up to black Buflex or Trizact 3000. I had a small 6”x 6” area with pigtails from the 2000 disc and I tried to sand it out with the blue Buflex disk, which it did.

I did the whole process dry except for the blue half sheets I decided to try with a bit of water to sand a couple of bigger dust nibs, it was hard to tell if it was cutting at first except for the fact that the dust nibs did go away, I couldn’t see the sanding sludge cause it was a solid white panel.

And just for the hell of it I sanded a factory Ford Explorer fender in Tuxedo black with the 6” Blue disc, then sanded the edge where it meets with the bumper with the blue sheet and water, then it was very easy to spot the sanding residue right away to confirm that it was actually cutting and not just gliding over the surface.

It was pretty easy to remove the scratches with Sonax CutMax and a black 3M polishing pad, it was the only clean pad in the whole shop lol so forgive me for not using a better cutting pad.

More experimenting to do, but so far it seems that I could go from Yellow 2000 to Blue disc and skip Buflex green for certain collision quick jobs. Next thing I will try is how easy is the jump from Buflex blue to Trizact 5000. Damn Trizact 8000 hasn’t arrived here in west Canada and I’ve been lazy to order it online from the States.
 

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interesting, didnt even know anything about the blue stuff. i have tried the bufflex interface pads and i just didnt understand those. both sides are the soft side of velcro so the disc doest really stick to the pad. it just falls off. since they are dry discs maybe they just dont work wet. the disc would just slide out from under the pad.

concerning your pigtails, they sounded like they werent really a problem but you will have less of a pigtail issue if the clear sits longer. when its soft its just way more prone to pigtails. also, whatever sandpaper or grit your using i think the cuts are deeper so it actually makes it harder to buff. i found the universal to sand and buff easiest at about the 3 day mark, average. 2 days in summer and maybe 5-7 in winter.

on a side note, i have used a bunch of the sonax cut max which i am really happy with but then i recently tried the meguires m100 which i also think is good and its cheaper. it performed pretty darn close to sonax and i didnt have a problem with scratches coming back on me from fillers which i thought was really unusual from meguires/3m. it is good stuff and 1/2 price of sonax. i used the whole bottle and now i am trying the 3d aca500. in a side by side test it outperformed sonax slightly and a ton of others so we will see. i have yet to try it out. my helper here used it a bit and thought it was way better then both the sonax and m100. only downfall is its another expensive one. the abrasive in it is some type of ceramic.
 
i believe pig tail are caused by heat 90% of the time. heat up the dust and it will melt into a ball and stick to the pad .
i'm still a CG user . i love the stuff . no mess to clean up . V38 on a black pad last forever .
 
interesting, didnt even know anything about the blue stuff. i have tried the bufflex interface pads and i just didnt understand those. both sides are the soft side of velcro so the disc doest really stick to the pad. it just falls off. since they are dry discs maybe they just dont work wet. the disc would just slide out from under the pad.

concerning your pigtails, they sounded like they werent really a problem but you will have less of a pigtail issue if the clear sits longer. when its soft its just way more prone to pigtails. also, whatever sandpaper or grit your using i think the cuts are deeper so it actually makes it harder to buff. i found the universal to sand and buff easiest at about the 3 day mark, average. 2 days in summer and maybe 5-7 in winter.

on a side note, i have used a bunch of the sonax cut max which i am really happy with but then i recently tried the meguires m100 which i also think is good and its cheaper. it performed pretty darn close to sonax and i didnt have a problem with scratches coming back on me from fillers which i thought was really unusual from meguires/3m. it is good stuff and 1/2 price of sonax. i used the whole bottle and now i am trying the 3d aca500. in a side by side test it outperformed sonax slightly and a ton of others so we will see. i have yet to try it out. my helper here used it a bit and thought it was way better then both the sonax and m100. only downfall is its another expensive one. the abrasive in it is some type of ceramic.

Yeah those Buflex pads are really weird but I figured I’d give them a try, for sure they won’t work if I want to try the blue disc with water since it increases the surface resistance greatly. I did a small side by side comparison by hand of the 3M 2000 disc vs the Yellow 2000 and they both seem to cut at the same rate but the 3M leaves deeper scratches that are harder to buff out.

I’ll probably order some of the 3D compound you have to try it out, thanks for the heads up.
 
i believe pig tail are caused by heat 90% of the time. heat up the dust and it will melt into a ball and stick to the pad .
i'm still a CG user . i love the stuff . no mess to clean up . V38 on a black pad last forever .


yes shine i totally agree. i have color sanded in some dirty ass places and found that is not as big of an issue as a soft/fresh clear. it balls up and the warm clear gets even softer making little pig tails. harder clear is more dusty and not as delicate. i still havent tried the cg compounds. one of these days i guess. i think i tried one time and they only came in small bottles. no qts or gallons.
 
Maybe revive buffing thread but Jim, i got the 16oz 4 bottle kit during holidays for nearly price of qt of cutmax.
Was (paused for the moment) cutting buffing FL sunbeaten 15yr old 1/2" Lexan sheets & V32 beat cutmax.
 
Though it may have been discussed before I haven't been able to find the answer to the question, how do you know when it's time to move up to the next finer grit when sanding clearcoat?
Any words of wisdom?
 
Sorry, Shine, but I don't get it. Shouldn't I be sanding in a criss cross patern, not a just back and forth?
 
I believe on clear you want to go in one direction per grit change. It's on fillers and primers that the criss cross pattern is used.
 
the only reason to cross hatch them is to find out which grit your failing to sand enough . 99% of the time it is 1000 grit your seeing because of jumping to 2000 grit. i work 1200-1500 the hardest . there is no reason to cross hatch clear . blocking clear is not going to gain much .
 
Got it. Thanks!! I had some major "texture" problems so I've sanded the entire car with 800 on a DA. 1000 followed by 1200, 1500, 2000 by hand is next.
 
you need to pay close attention to the 800 . make double sure they are gone before moving on from 1000 . 800 is a reclear grit for me .
 
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