Need help! Sand marks problem!

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mangahaspaulo

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I sanded my car using 1,200 grit then 2,000 then I buffed it with 3m compound and then polished it with 3m polish using my da but it didn't show any good results. I was expecting to have a mirror finish.
 
I think 3m is to be used with a rotary not da.
 
If you can see the texture is rough and wavey. Can it still be a mirror finish?
 
Try some Meg's d300 on a microfiber cutting pad then finish up with Meg's 205 on a soft foam pad.
 
If you are looking for flat zero texture or very little texture more sanding is required.you say it's wavey maybe the primer wasn't blocked out correctly or its your sanding technique.I would invest in a rotary if this is gonna be the whole car then finish down with da.or get the correct products for the da.1200 to 2000 is a big jump.wouldnt hurt to get some 1500 grit.More than likely hard to say,your not leveling the 1200 with the 2000.pics are hard to see,but that would be my guess on correcting the paint.Every paint system is a bit different .some you can start at 1200 to 1500 grit others you can't.my advice would be 1200 1500 2000 and take your time.
 
IME, 2000 on a block flats plenty quickly and leave slightly less deep trails than the lower grades...
Be sure to rinse regularly and change out regularly to maintain the cut rate...
Then block with 3000 aiming to eliminate any and all trails cos if you don't now you'll see then right through to the end...
Then use 5000trizact on a DA... Simply cos it's quicker than wool on rotary... And if kept clean seems to leave less tail marks..
Now get onto a cut foam pad and compound (scholl s3xl gold) for example..
Now a polishing foam pad and some fine polish line scholl s20
Finally Jewell with a rotary finishing pad and some finishing polish.. Eg car pro reflect..
It's not quick, so get over that before you start..
Now just focus on getting every section correct in its stage that way you won't chase issues on a later finer stage...

All the best.. I feel your pain..

Ps careful on the edges and profiles.. Strike through is always a risk ..
 
Great advice.on a another note all sandpaper is not created equal.I don't recall the last time I used a block for sanding.mirka foam on a machine is great and quick.situations like this require money and time for the best outcome.paper sanding on some paints are destructive and gouge and scour the sanding process.Great advice though.
 
In my case I got it off with 5000 following 7000 grit wet sand paper. For ultimate result UC and M205 did the job, oh and it was done by hand. For this kind of job the gouge will be necessary I assume.
 
VeloNYC said:
In my case I got it off with 5000 following 7000 grit wet sand paper. For ultimate result UC and M205 did the job, oh and it was done by hand. For this kind of job the gouge will be necessary I assume.
Click to expand...

7000? May I ask, who's the manufacture?

Thanx...

Bill
 
GSKR, when I say block. I cut a block from a high density closed cell foam sheet... Firm enough for flatting, enough give the help prevent edges etc...

I would totally DA this stagehand open flatter panels.. On my car it's all bloody curves concave and convex. So by hand with great lighting was safest....

OP Pick what ever works for you..
 
I find no lower than 2000 is required for scratch removal. You go through more sandpaper sometimes but you don't have to worry about getting all the 1200 grit scratches out.

I've worked for years in body shops and ill tell you, as far as 3m and other similar products are concerned they are not designed to remove 1200 grit scratches. They are a ##### to get out even with a rotary buffer and wool pad. I would never go lower than 1500.

Also those scratches won't come out easy with a polisher. You're gonna spend a while on those.

Sanding should really be followed by a rotary with a wool pad, then for a swirl free finish I follow with the same compound with a cutting pad on a da, then polish with a da.

Also be aware a lot of newer compounds are filled with oils and it may appear the scratches are gone but if not buffed thoroughly they will show up later.

After buffing take some degreaser like purple power and wipe the area before proceeding to the next step.

A final note, a dual action POLISHER is just that, a polisher. Yes you can do amazing things with one, but you'll spend 1/4 of the time using the above steps.

Sent from my VS987 using Tapatalk
 
Looks like this was done via hand sanding. If that's the method it also appears that there was no support between your fingers and the sandpaper. 3M makes rubber squeegees that will make the sanding more consistent. Was the wet sanding done with 3M WETORDRY paper ? Also when buffing you don't mention the tool or pad type or which 3M compound etc? So here goes with my 35 years of experience at 3M. If you are doing this by hand soak all of the paper in a bucket. Have twp buckets. The clear coat will build up on the WETORDRY paper. When it does take that sheet dip it into bucket #2 ( the rinse bucket ). Grab the same grade from bucket #1 ( a clean piece of paper same grade ) and continue. If you do not have a wetordry squeegee use a credit card. Id you sanded with a 1200 in a north south direction the next finer grade go east west. When the north south scratches disappear by going east west only then will see that you have removed the previous step or not. Good luck
 
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