How do you wet sand? Is it a good idea?

[Gayle]

Here is the deal. Please read the whole post and don't just start throwing detailing product recommendations at me.

I have stone chips in the hood, a vandalism inflicted scratch over the gas door, and generally dull paint. I noticed that it seemed dull and yellowish compared to our prior 525 of the same year. I noticed it seemed really lame next to liquidtigers paint job or Brandon J's--both of them have had new paint jobs.

I talked to the body restoration guy (Robbie) at my indy's today. I have seen touch up work Robbie has done on old porches and its amazing.
My indy has one of the leading coupe restoration operations in the country. People pay them to let their coupe's sit on their lot for up to a year waiting for them to have time to be restored. The mechanics do the engine restoration, Robbie does the body prep work and interior work and then another place paints them. I respect Robbie's work so I respect his opinion but I am totally confused after talking with him.


http://www.bimmerdoc.com/restorations.php

This is what Robbie told me. It looks like my hood has been repainted before because the color doesn't quite match. There are enough chips it may need to be repainted. It looks like the top of the front bumper has been repainted too.

He says that white is extremely forgiving and what he would recommend is wet sanding and filing in the chips with layers of paint using an artist's brush and doing wet sanding with 1500 grit between layers.

He said the whole thing needs polishing. To which I said, it has been clay barred twice. He said it is not the same thing. I didn't tell him that I have also treated it with Klasse all in one and a massage with my porter cable and it is still dull. Robbie slapped some 3m product on a spot to show me how he thought it would look.

I asked what is wet sanding? I don't think I understood the answer because it sounded like he was saying it was rubbing compound. I am asking him what is wet sanding and he is waving this liquid 3m product at me and saying it is rubbing compound. He said I need to take a very slight amount of paint off. He started discussing the different 3m products. I figured I would just look it up cause none of what he was saying was sticking.

I am very familiar with rubbing compound. Hubby parks by ear and rubbing compound has been the miracle of the modern world as far as taking a variety of paint that doesn't belong on our cars off. I am very gentle and have had no problems with it. I have a hard time imagining using it on the whole car.

I searched the archives and found this.


You're not doomed at all. Before having it sprayed all over, try using wet sanding paper not lower than 2500. Use very large amounts of water and a rubber sanding block for the flat surfaces. Roundings in the bodywork should be done by hand. Sand the car in smal slow circular motions( do not apply force, it's more delicate then Naomi ) until you reach a whitish finish of your top coat. You can check occasionally why whipping it dry between sanding. Be carefull not to go through the top coat( the white mat finish will disappear and the black paint will start to show !!!!) After having sanded the whole car up to a mat white finish, polish the car with a machine at low rpm with a low cut polish ( 3M is the best there is for this job, blue cap ) If done right you will see the shine coming back, after this use the M red cap at high RPM to finish the job. I use this process with every car I paint. It looks like a mirror afterwards.Just a good job in the spit and shine section.

Paper and block doesn't sound the same as rubbing compound. And the part about going through the clear coat in the post sounds down and out SCAREY! And I asked Robbie if I had clear coat. He said yes but this was based on the year and the color. I, of course, argued that not all whites have clear coat. No resolution there.

So here is the bottom line. I am confused.

I think wet sanding, rubbing compound, and polishing are three totally separate things. Right? What should I do? How do I do it?

Suggestions to read road fly and autopia would not be helpful. I read both sites front to back last year and bought a lot of detailing products including the porter cable and used them. I did thorough detailings of 5 cars last year. I like to detail cause I do a better job than the professionals. But the car I car the most about is not responding to what I have done. Help!

[califblue]

G- call me at home..;)

[califblue]

WOW...
I think i need a smoke after that phone call;) ...all that talk about rubbing & polishing:D

[John 535is (Sydney)]

Gale,

he is talking about rubbing the paint back with wet & dry sandpaper. Its the black paper (not technically sandpaper but made of a silica compound) which you can use with water. You can buy grit counts from about 200 to 2000. the higher the number, the finer the grit. If you spray a panel using one of those touch up spray cans you will find the finish is not the same as the original flat paint. Using about 1000 -1500 count paper, with a sanding block, immerse the paper in water and rib the finest of paint layers off the top, so the finish is like the original. Countinue to add water to the paper while rubbing.

This is not something I would attempt on a large panel like a hood until you know what the finish will be. If the grit is too harsh, you will get fine scratches in the paint finish which you then need to sand out - you could end up with a very thin paint finish. Give it a go on an old panel, or small section on the under side before attempting the most obvious panel on the car.

This in my book is kinda a last ditch effort, knowing if it doesn't work, I have to paint the panel anyway. You can also add some dishwashing soap to the bucket of water to add some lubrication to the water. Essentially the water cleans the pours of the paper so you don't get a peice of git caught in the paper and scatch the hell out of the paint.

#M call it Wet& Dry but there are other brands available at you parts store.

John 535is

[winfred]

wet sanding is a step beyond clay barring and is not for the weekend warrior, it's fairly hard to really screw up a paint job with clay and unless you really don't know what you are doing a buffer is tame, wet sanding is just the next step and it's the perfect time to fill the chips

[jrobbo]

Gayle,

I know you didn't want links, but there is a wetsanding forum over on the meguiars website ( http://meguiarsonline.com ) where there is lots of good info, but also lots of people that have done it before that will be able to answer your questions in detail

John

[Gayle]

Thanks guys. I appreciate your input, moral support, offers of help, and the link.

And I had not seen that website. A detailing thread devoted just to wet sanding is great cause it gets a lot of people's input. I feel more comfortable with that than an article written by one person. Thanks again.

[jbraswell]

Ive been doing detail for about 4 years now. If you do not have experience, wetsanding your car is definately not a good idea. Removing sand scratches is pretty tedious as well, and can take a huge amount of time. I would start with some spare panels for practice. I have burned through my fair share of cars in my time, but that all comes with learning. I usually use 3m wet or dry 2000 grit, followed by 3M extra cut, then meguiars diamond cut, then a polish mix and finally glaze. You can sometime skip the second cut on some colors, but extra cut swirls pretty badly (especially on dark colors).

I wetsanded my car to remove the pinstripe, and it looks incredible in person. pictures just dont do justice for really nice black paint.

[Alan_525i]

I'm surprised that no one has noted that Liquid Tiger's car (being a 95 IIRC) is a different Alpine White than your 91 (I think). My 1990 (which has always been VERY well taken care of) is noticably "yellower" than my friends 96 328i. The color is different.

Also, wet sanding a car provides a VERY different finish from rubbing compound. Rubbing compoud takes paint off also but it doesn't smooth the finish nearly as effectivly. A properly wet sanded car has quality that can't be described well until you've seen it. Especially on black, the paint looks smooth like glass. Rubbing compound and such will still leave that "orange peel" that some people like. I think a bit of peel is a good trait in a paint job as it gives the paint some life/movement. A wetsanded car (esp dark colors) will have a very flat appearance. Great shine and depth, just a very non sparkly look as all the light is reflected back at closer to the same angles.

Also, note that wetsanding IMHO is really only for non-clear coat cars. (You are OK Gayle as your car does not have a clear coat). I know some people wet sand clear coat to remove imperfections in it, but I think its a big risk as clear coat isn't the most durable finish out there.
I know some will disagree with me on this point and that's OK.

Hope this helps, ask any questions you may have.

[Booster]

Gayle,
.........I've got over 24 years experiance in all levels of paint finishing and refinishing. What has been said prior is true about this not being for the faint at heart. In fact it is usually more overwelming to the tough DIY'er than expected.
I'll skip the long tutorial of all the information and simply say......Have the hood and front cover pro painted in Eurothane......and attept to wetsand the remainder of the panels by using 3M's wet and dry 2500 grit amd ,or 3000 grit with some dish soap in your dilution bucket.
Your in effect just going for a deep cleaning here, rather than a texture "knockdown" which is why most of us get paid to do it. Slight scratches or topical abraisions will sand away with additional work.
By using these lighter grit papers.....you'll actually be able to use an oscilating orbital buffer to rub out the new light wetsand haze newly created. There is a saying I use frequently....." you have to make them ugly, before you make them pretty" !
best of luck..............Vinny:)

[Gayle]

I'm surprised that no one has noted that Liquid Tiger's car (being a 95 IIRC) is a different Alpine White than your 91 (I think). My 1990 (which has always been VERY well taken care of) is noticably "yellower" than my friends 96 328i. The color is different.


Also, note that wetsanding IMHO is really only for non-clear coat cars. (You are OK Gayle as your car does not have a clear coat). I know some people wet sand clear coat to remove imperfections in it, but I think its a big risk as clear coat isn't the most durable finish out there.


Yes--Josh's and the other white at bimmerfest were alpine white 3 and mine is alpine white 2 and mine is noticably yellower. But that said, for about a month, we owned both a 90 525 and my 90 535, both alpine white 2, and my 535 is just much yellower looking. I wondered if someone put a crappy product on it that yellowed the paint. In the picture below the 525 looks more yellow, but side by side the 535 is more yellow.


http://i24.photobucket.com/albums/c21/e34Gayle/5aatwins.jpg


I know you have posted in other threads that the apline white 2 doesn't have clear coat. I think I have seen other people have a different opinion. Robbie, the restoration guy said he did an 89 white bmw that had clear coat so mine should. Also, the clear coat was starting to peel in one spot on our 525 so it had it. I am getting the impression that some do and some don't. Since it is not peeling on my 535, I really don't know if it has it. Is there any way to look it up by vin?

Again, thanks for the information and opinions.

[Alan_525i]

My understanding is that non-metallic colors didn't get a clear coat until 1995. That's the only info I have.

FWIW, the repainted panels I have DO have a clear coat. There is nothing that says a color can't be matched as a two-stage.

[jbraswell]

No thats not it, we have an '87 schwarz e28, '88 alpine II e30 and my '92 schwarz e34, all three are base clear. Of all the BMWs I have buffed, the only 2 that were single stage were both ETA e30's. I think an 86 and 87.