Cutting and Buffing Questions

[JR_Charger]

I've currently sanded down to 1500 grit, is it worthwhile to make a 3000 grit pass on a driver?

I bought a used buffer that came with a 5" backing plate, but the instructions say to use a 6" plate. Will a 5" damage the machine? I'm doing smaller areas so the 5" will be o.k. if it doesn't damage the buffer.

How far will a foam pad go, before it has to be tossed?

 

[azblackhemi]

Going over it with finer grit will mean less buffing. Your choice, more sanding or more buffing. Personally I use finer sandpaper before buffing.

 

[slimt]

Do your sanding in gradual steps. 15 to 2000 then to 3000

 

[zyzzyx]

I like using the 3M Trizact discs with a foam pad on my D.A. I use 1500, then 3000, then
5000, then 8000grit wet as per their instructions. When done, you don't need to cut much,
you only need to use their special polish. The pads last a very long time as long as you keep
them wet while using. At the cost of paint and labor, you don't want to screw it up now! Check
out the 3M YouTube videos. You'll be amazed!

 

[zyzzyx]

 

[AR67GTX]

I get more out of 2500 just prior to polishing then just about any other grit. Wizard compound on a foam pad after working through 1000 or 1500, 2000, and 2500 comes out really nice. Trizact pads are really nice but I’ve only used them for detailing and touch up. I think by the time you work through Trizact 3000 and 5000 pads I doubt you would have to do anymore than barely touch it with polish and a buffer. I wasn’t even aware they had 8000 grit pads.

 

[slimt]

Also. If you wet sand. Try a little sunlight dish soap in warm water. Soak your wet sand paper well. It softens the latex paper back. So it does not dig into your new paint. Youll find that it cuts better, the paper wont stick to the panel and crease

 

[JR_Charger]

Is dry sanding an option? I have done nothing but wet sand.

I don't know about all this sanding, especially wet sanding with a machine on a vertical surface. It's hard enough to keep a vertical surface wet when I have a hand free for the squirt bottle. It seems like a foam pad and rubbing compound would be a better option, but I haven't done this stuff before.

 

[eldubb440]

sand a lot, buff a little........the trizact pads are like little sponges with some sort of soap, they dont require a ton of water, they hold water

I start with 1500 purple disc dry with interface pad, 3m but not trizact........ it knocks down the texture quickly, stay off the points and edges.....then i go around the edges with 2000 wet by hand until flat......then over the 1500 scratch with 2000 wet, its already flat so pretty easy........then 3000 trizact, 5000 is an option especially for very dark colors/black; but not necessary........3000 finish will buff quick and easy with a wool pad followed by foam pad

 

[72ls5fla]

if you want paint wobble gone and really flat, wrap a hard stick with the sand paper (like a paint mix stick, just harder wood or plastic).
wet sand with that. takes longer but results are great.

if you want a factory type finish us a hard pad when wet sanding.

last sand (imho) nothing less 2000
and as stated above - more wet sanding LESS buffing.

as for cutting/polishing -
think most of what is available now are chemical cutting compounds and polishes.
more you get done upfront (with wet sanding), easier things will be for cutting and polishing.

and FWIW -
3M Trizact system is for production body shop work.
using a DA with Trizact will not do anything for making a flat surface. very good for spot work and quick/dirty all-overs.
but only way to get the clear surface flat and have no paint wobble is using the stick when wet sanding.


my 2 cents...
Bill

 

[AR67GTX]

Very good point. I block sanded the two cars I’ve painted with my initial (coarsest) cutting paper and water with a little soap. On flat surfaces I use a thick paint stick or sometimes I cut wood blocks from oak or poplar wood which is usually very straight and stable for sanding blocks. Sand back an forth with a bit of angle and reverse the sanding direction to angle slightly the other way until the orange peel is gone. You want to use a varied sanding pattern so you don’t sand in a groove or distort a flat surface. On curved surfaces I used either a small block or a stiffer, thin rubber sanding pad and sanded across the curve in one direction at 45 degrees and then back in the opposite direction at 45 degrees, just like you would blocking out primer. Cut it until there is no sign of orange peel and then go to the next sanding grade you have decided on. I did the hard blocking with only the initial cut as trying to block sand with finer grits (2000 and finer) accomplishes little. For the finer grits I use the flexible sanding pads with the paper wrapped around it and water with a few drops of dishwashing soap. If you don’t use a pad you risk leaving finger pressure grooves from your hand/fingers in the final surface.

 

[Chris Many]

On my latest project I did a half and half approach. Some hand blocking up front and then switch to trizact after. came out pretty nice. but if you want super flat you really got to block it by hand with all grits.

1970 FM3 Plymouth Satellite Convertible Restoration - Painting

 

[69L48Z27]

I start with 800, then 1500, 2000, 2500, 3000. Use 3M Perfect-it use wool for the white, foam for polishing grey and blue. PPG DCU2021. You‘ll find every clear to have a ‘personality’.

Your foam pad is toast when it looks chewed up. They’ll start coming apart too. You’ll know when it’s time.

 

[JR_Charger]

I haven't heard of this "paint wobble." I've been sanding with a sponge for backing and haven't seen anything strange yet. Maybe it will show up when the gloss increases. I have been sanding with a cross hatch pattern.

I picked up 2000 and 2500 grit sandpaper today. O'Reilly's had a 3000 grit 6" disk. Nothing higher than that.

 

[zyzzyx]

When you sand with anything under 5000, you have to use "Compound" to remove the scratches
and "Shmooze" everything over. When you go all the way to 8000, you are polishing and not for very
long! It takes about three Trizact discs to do a whole car so even though they are expensive, they
last a long time.

 

[eldubb440]

When you sand with anything under 5000, you have to use "Compound" to remove the scratches
and "Shmooze" everything over. When you go all the way to 8000, you are polishing and not for very
long! It takes about three Trizact discs to do a whole car so even though they are expensive, they
last a long time.

when did they come out with 8000? I have to check that out......

edit....lol thanks

 

[dadsbee]

This was done to 8000...

 

[zyzzyx]

HENS 2TH Is very Beautious!

 

[AR67GTX]

I haven't heard of this "paint wobble." I've been sanding with a sponge for backing and haven't seen anything strange yet. Maybe it will show up when the gloss increases. I have been sanding with a cross hatch pattern.

I picked up 2000 and 2500 grit sandpaper today. O'Reilly's had a 3000 grit 6" disk. Nothing higher than that.

l‘m not completely sure but I think he‘s referring to to how the gun fan pressure of the paint spray can move the the wet paint around on the surface and leave subtle waves in the cured surface. I think it’s a trait more associated with the clear coat. Blocking flattens the subtle waves and wobbles before compounding/polishing.

 

[69L48Z27]

That‘s why I start with 800 on a block, you need something thats going to actually cut and level the waves and peel. Seems anything over 1500 won’t really cut or shape anything. Using a sponge isn’t helping either. You’ll get all the junk out of the paint but you won’t straighten the top layer.