# Wet Sanding - What am I doing wrong?



## OCDDetailer (May 17, 2011)

Ok so tried wet sanding for the first time the other day.

I bought a sanding block and Meguiar's unigrit paper (2000 and 2500 grit). I am using a G220v2 with Meg's 80 and 83 to remove the sanding marks.

I am removing the sanding marks fine, not a problem with that but it doesn't seem to be taking the stratch out, the stratch isn't deep enough to get your finger nail caught. I made sure the surface was really wet and starting applying light pressure back and forth over the stratch, (tried with both 2000 and 2500 paper) while spraying more water to keep it wet. I did this for maybe 1-2 mins, the paint is very soft and could see the clear coat coming off, so didn't want to keep sanding for too long incase I went through the clear coat. I then wiped clean and took the marks out. 

Am I not applying enough pressure? Using the wrong paper or not giving it enough time? All 3 or something totally different!


----------



## lukeneale (May 14, 2011)

i would wet sand with out a paint detection device mate


----------



## Magic Detail (Jul 25, 2010)

Are you using a PTG? Sounds like it's obviously in the clearcoat, but quite deep into it - so you have not removed enough if you can still see it. Wet sanding doesn't remove as much clearcoat as you think...

You'll probably need to give it another go, but going in blind without a PTG means you either need big balls or a big wallet if it goes wrong and you go too deep! Your technique seems fine, you don't need to apply anymore than light pressure - let the paper do the work.


----------



## OCDDetailer (May 17, 2011)

No PTG although sorry I forgot to mention I am practicing on a panel I bought. I had thought a few times about buying a PTG though! 

If my technique seems fine then I will give it another go but try sanding into the clear coat for longer. And in the meantime do some research into a PTG!


----------



## Magic Detail (Jul 25, 2010)

You could also try a coarser grade of paper, like 1500 or even 1200. This bites deeper into the paintwork. Refine with 2000, 2500, 3000, and lastly 4000. Glad you're practicing on a scrap panel mate, best way to learn if unsure. Bet you're glad you never tried this on your motor!


----------



## John @ PB (Aug 25, 2010)

If it's not deep enough to catch your nail in it _and_ the paint's soft, why on earth are you wet sanding?

Seems complete overkill.

Machine polish it.

Seems to be a fad at the moment to wet sand everything and in 99% of cases there's no need to.


----------



## hotwaxxx (Jul 12, 2007)

John @ PB said:


> If it's not deep enough to catch your nail in it _and_ the paint's soft, why on earth are you wet sanding?
> 
> Seems complete overkill.
> 
> ...


Agreed. It seems to be the thing to do at the moment.

I've detailed hundreds of cars now and I've only ever had to wetsand areas around 10 times over that time to remove the stubbornest of deep scratches. You should always use the least abrasive action and then work your way up if you cannot remove a RDS. In some cases, it is best to leave a scratch in the paintwork rather than harming the clearcoat for the sake of one detrimental mark in the paint.

However, as you are practising on a panel then that is fair enough. Just let the paper do the work. And as someone has already mentioned, heavy compounding is likely to remove more clearcoat than wetsanding with 2000 and 2500 grit.


----------



## OCDDetailer (May 17, 2011)

I have a few stratches on my car and family that won't machine polish out so thougt I would try my hand at wet sanding. As I said I bought a panel to practice on in which I have made several stratches at different depths.


----------



## John @ PB (Aug 25, 2010)

OCDDetailer said:


> I have a few stratches on my car and family that won't machine polish out so thougt I would try my hand at wet sanding. As I said I bought a panel to practice on in which I have made several stratches at different depths.


To be honest, you'd probably be better using your scrap panel to practice machine polishing: if you're working on a scratch you can't feel with your nail on soft paint and machining isn't taking it out, there's probably something in your machine technique that needs looked at.

What pads and polish are you using and what car did the scrap panel come off?

(Whether you're machining or wet sanding, a paint gauge would be a very good investment :thumb


----------



## Kelly @ KDS (Aug 4, 2008)

simple answer is

removing scratch you dont wet sand ,

all you are doing is reducing the amount of material either side if the scratch , so less is left for you to use edge of pad or wool pad to "round off" the edges of the scratch .

Demo'ed this on my training days (one to one training days) why you would want to lower the paint depth over a larger area beats me.

Wet sanding only works for removing orange peel , fall out , water etching , (thou last 2 can be corrected with correction only) , the amount of times i see someone post a collection of pictures showing swirls and scratches and the the wet sanded panel (but you can still see the deep scratches through the sanding marks?) then finally all machined back with scratches removed .

the correction is what removed the scratches.

Have you ever seen me post a picture of wet sanding to remove a scratch ??

the only case of this would be if i had touched in the scratch first with paint .

kelly

www.kdsdetailing.co.uk


----------



## hotwaxxx (Jul 12, 2007)

Kelly makes a fine point.

When measuring levels of paint before wetsanding and after you will find around 4-6 microns removed at most. However, buffing the area with a rotary with a compound polish and pad and you can see that figure hitting closer to double figures with a PTG.

So when you see some of the pros who seem to 'wetsand' a scratch out of paint - they essentially are not. All they are doing is removing the clear around the scratch a fair level and when you use your rotary/pad/polish to remove the wetsand scratches, it is at this stage that the scratch too will be removed.

You will only find you need to 'wetsand' a scratch as a means of moving clearcoat quickly on hard paints such as BMW clear for example where it may be far easier to remove clear through wetsanding than rotary buffing. 

I probably haven't explained that well but in essence, wetsanding alone does not remove a scratch. It simply acts as a method of removing clearcoat around the said scratch as an alternative to doing the same with a rotary machine.


----------



## Doug_M (Jul 12, 2010)

Could you not fill with a laquer touch up, let it cure, sand or compound smooth?


----------



## Kelly @ KDS (Aug 4, 2008)

Doug_M said:


> Could you not fill with a laquer touch up, let it cure, sand or compound smooth?


Of course and do this sometimes , the next part to the problem is

if you fill the scratch up too much then wet sand to "level" the paint and scratch you face the danger of breaking through either side of the part/ scratch you filled too high .

same for wet flatting out a run/sags in fresh new re-paints , when the run is heavy there is a very good chance of flatting to far either side of the run .

This is when you need to use something with a sharp cutting action to remove most of the excess paint before wet sanding .

kelly

www.kdsdetailing.co.uk


----------



## OCDDetailer (May 17, 2011)

Thanks guys, Im still learning so keen to take on opinions etc.. 

I am using a G220v2 with hex logic pads, white and orange for correction then Meg's 80 and 83. The practice panel I have is from a rover 25, blue, not sure how hard/soft the paint is but I would guess its similar to MG, soft.

I am thinking about getting Meg's DA system. Will this remove the stratches I talk about? I have tried P1 on the stratches aswel but that doesn't shift them.

Its my birthday next month so am going to ask for a PTG


----------



## Mirror Finish Details (Aug 21, 2008)

Kelly @ KDS said:


> Of course and do this sometimes , the next part to the problem is
> 
> if you fill the scratch up too much then wet sand to "level" the paint and scratch you face the danger of breaking through either side of the part/ scratch you filled too high .
> 
> ...


As Kelly said a paint runner or plane is ideal to knock the build up or runs off. The one I use can shave just shy of the origional paint which just leaves a bit of blending with 3000 grit paper.


----------



## jamieblackford (Jan 17, 2012)

I've read this thread and think I understand everything. Only thing I don't understand is how does wet sanding remove orange peel if polishing with a rotary does not? Or does it? If so why do people wet sand atall? Thanks


----------



## jamieblackford (Jan 17, 2012)

Anyone?


----------



## ant_s (Jan 29, 2009)

jamieblackford said:


> I've read this thread and think I understand everything. Only thing I don't understand is how does wet sanding remove orange peel if polishing with a rotary does not? Or does it? If so why do people wet sand atall? Thanks


Because when using a pad on a DA/rotary the pad conforms to any tiny deviations in the paint finish (the hi and lows of the paint that cause the OP look) whereas a harder media like sandpaper on a flatting block will take the 'tops' of the paint bumps and leave the paint much flatter and removing the OP.


----------



## georgey2011 (Oct 24, 2011)

Ive got scratches on my car i cant get out either, ones that dont catch my fingernail either.

Ive got two on roof and 2 on bonnet on a silver SEAT leon, and a scourer scrub mark on the roof too, just wont come out, tried megs 105 or 205 is it ? compound on orange menz pad, the tried a white menz pad with fg500 cut, doesnt want to know with a da6 pro... scratches are still there!


----------



## georgey2011 (Oct 24, 2011)

I spent an hour doing half my roof and bonnet earlier with menz fg500 and a white pad primed with quik detailer, made a bit of a spatter but got 90% of the marks out, i feel confident in filling the ones i cant now and then polishing them back, time and patience also its easier to use the edge of the pad on a medium speed and just go over the scratchmthan the whole pad on full speed going over and over the whole area


----------

