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help with da polishing

6K views 16 replies 9 participants last post by  EG30 
#1 ·
Ive polished about 4 cars using my d.a ive tried different pads (all from china) ive used their most aggressive pads,used megs ultimate compound,megs 105,and a couple from autobrite direct..........a get a very good finish,but i cant seem to remove sanding marks ,i can fade them out but cant get rid of them after using 1500/2000/2500 grade.

what am i doing wrong?

im doing a good 5-6 passes but unfortunatley cant get rid of them,if i find a mark/blemish i can wet sand it,get a shine back up,but i can still see sanding marks.

it is audi paint,and with it being black...........well you know what i mean,always finding new mars/blemishes lol
 
#4 ·
100% no.

its not one car ive tried on its 2 and still same results,no pics as they were just family cars,the sanding marks are only visible when very close..........is it the cheap chinese pads?,i find megs 105 not doing anything cut wise.
 
#6 ·
The same as Benfr16 i have very little experience of sanding marks but I would say always use quality stuff.

Maybe the Chinese pads are great but I'd go for Scholl Spider pads or Lake Country Hydrotechs or some other well known, reputable pads from one of our forum supporters.

Maybe teaching granny to suck eggs but have you watched the Junkman videos and read Dave KG's article?

http://www.detailingworld.co.uk/forum/showthread.php?t=281047

http://www.detailingworld.co.uk/forum/showthread.php?t=63859

Good Luck with it.

Andy.
 
#7 ·
More to the point, why did you have to wet sand the paint in the first place?
Audi paint is usually quite hard so 105 plus a cutting pad from say CG's Hex Logic range should have shifted any blemishes that existed.
A quick question, but did you use a Paint Thickness Gauge to check the paint depth first, then to see how much paint you've removed?
 
#17 · (Edited)
Your current situation:

Hard Audi black paint with 1500 sanding scratches applied by hand.

weak DA with 8mm stroke

soft to medium chinese pads

any leftover faint sanding marks being noticeable being a dark coloured car.


Let's see if your new firm pads makes a difference. On softish pads just by the virtue of the pads flexing you could easily lose up to 2-3mm of stroke and thus the DA doing very little on the paintwork. A 15mm DA would mitigate this by having a lot more stroke to play with.

One pad I find great with the least amount of flex/compressiblity is the Shine mate green pad. It's too stiff in many applications but in your situation it could be the saviour.

Regarding wetsanding, it takes a lot of effort to rid of the 1500 hand sanding marks. Do not assume a compound that is capable to removing 1200-1500 grit sanding marks would remove 1500 sanding marks in a 3-4 passes completely.

While it's easy to remove 90% of the marks pretty quickly, there is always a small percentage that is hard to remove ie deeper scratches that requires further refinement with 2000 grit sandpaper first.

sanding down with 1500 is the easy bit, refining with 2000 and finer takes longer than the initial 1500 sanding stage.

I avoid 1500 if I can help it when I need to wetsand RIDS. On the occasions I wetsand I start with 2000 grit foam backed abrasive discs on a DA on speed 1 and then further refine it down to 3000 grit before buffing the area with rotary buffer and then remove holograms with a DA. I use ONR as the lube for wetsanding rather than water or soapy water.

Regarding the chinese pads, I have tried numerous suppliers from Aliexpress and none of them are more than medium to firm despite what they advertised them as hard cutting pads. Their medium firm pads are like polishing pads at best so there is no need to even bother with their soft finishing pads. There are some good bargains on Aliexpress for detailing products but pads are not one of them, they are not that cheap and you are much better off buying a known value brand such as Shine Mate.

Try refining the area with 2000/2500/3000 if firm pads on M105 won't remove sanding marks. There is also the option of more aggressive compound on a firm pad ie Menz 300, Scholl S2 etc.
 
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