wet sanding rear bumper

[WhiteCamaro88]

as i am not experienced with wet sanding/ and or a rotary i have got a good deal on a bunch of scarp body parts from local auto body shop , now how do i kno when i have take off to much / to little clearcoat wen wet sanding same thing goes when using 84 or 85 with a cutting pad ? i hear never use rotary on a rear bumper but it needs to be wet sanded due to runs/drips

i heard mastering the roatary is a little easier then mastering west sanding any tips or opinions pleasee fill my n00b self in

excuse the word useage im in a rush

[BondoKing]

We will make it real easy then bro, get some Unigrit sand paper that MG sells.. It is Nikkens brand and is the best on the market IMO... Get 2000 grit... It will take a little longer than if you used a lower grit, but since you are new this is fine and you are only doing a bumper so it will not take long...

Make sure the surface is super clean... Get you a bucket of water and you can use your hand or a soft flexable block.... Let you paper set in the water and add some 00 car wash in for a couple hours before you begin... Sand the clear until it is FLAT... What I mean is paint has what is called "orange peel"...Looks like the surface of an orange, hence the name... What you are doing with the paper is leveling the clear all to the same height... When this is done you will know because there will not be any bumps left and the panel will look chalky white and flat..... where as when you started sanding and checked the panel would have all that texture...

As long as your painter put enough coats on there should not be an issue with sanding the clear... Who ever told you to not touch a bumper with a RB is just plain scared... I do it everyweek on something... No big deal, just a learning curve is all.

Use the w7000 maroon foam pad.. It will be kinder than a wool pad... Go slow and you will be okay.

IF this is not clear enough just ask me some more.. I will look and see if I have any pics that might help on the pc

Matthew

[BondoKing]

Found 2 quick pics for reference on the web...Some guy just painted this thing and you will see allot of texture in the first pic, and the second show it sanded FLAT... That way you know what I am talking about...Pics always make it easier

Best of luck


[IMG]http://archive.meguiarsonline.com
The other pic that matched the lower one used a weird photo system... It would not load....Anyways you get the idea...This is orange peel and it will show up when sanding until it is gone




Panel sanded flat

Sorry they are soo small, it was the best I could do quickly

Matthew

[WhiteCamaro88]

thanks for the help i really appreciate it , now on thing im confused on is the pads i know 8006 and 9006 but as far as wool and cutting pads i need some help as for there applications . ur answers are very clear the only thing is im still a little unsure on how i kno wen ive cutt" enough with the rotary after wet sanding

ps i have alot of runs and drips but no orange peel but the scrap pieces from the body shop i got might have some orange peel ill get back to u on that one

how much practicing shouldi do be4 lettin the rotary touch my car

[Shiny Lil Detlr]

Originally posted by BondoKing
We will make it real easy then bro, get some Unigrit sand paper that MG sells.. It is Nikkens brand and is the best on the market IMO... Get 2000 grit... It will take a little longer than if you used a lower grit, but since you are new this is fine and you are only doing a bumper so it will not take long...

I disagree. For a first timer, starting with 2500 or 3000 is a smarter move. 2000 is still agressive enough to do some damage VERY quickly if you apply a bit of pressure.

[Shiny Lil Detlr]

Originally posted by WhiteCamaro88
thanks for the help i really appreciate it , now on thing im confused on is the pads i know 8006 and 9006 but as far as wool and cutting pads i need some help as for there applications . ur answers are very clear the only thing is im still a little unsure on how i kno wen ive cutt" enough with the rotary after wet sanding

ps i have alot of runs and drips but no orange peel but the scrap pieces from the body shop i got might have some orange peel ill get back to u on that one

how much practicing shouldi do be4 lettin the rotary touch my car

Do more practicing than you think you need. Honestly, unless you have spent a long time using a G100 (by that I mean a few hundred hours, over the course of YEARS) you'll have quite a learning curve with the rotary.

The best way to know when you've cut enough with the rotary, is to just keep checking it. Especially if you're inexperienced, you need to stick with light, brief passes, and keep inspecting it. You want to get to that point where you can just BARELY see the tracers (like as in they look like a haze, not visibly sanding marks). Then switch to a regular, less agressive polish to finish the job.

Again, practice makes perfect, and you'd be wise to practice until you're 100% confident in your abilities -- and then practice some more.

[BondoKing]

Originally posted by Shiny Lil Detlr
I disagree. For a first timer, starting with 2500 or 3000 is a smarter move. 2000 is still agressive enough to do some damage VERY quickly if you apply a bit of pressure.

We SLD, will have to agree to disagree here then... Ive been doing this almost 14 years now (painting cars), and 2000 grit is not at all agressive peroid... If you climb up the ladder even more with grit he will work himself to death and more than likely give up before accomplishing the goal..

As well he has said he has lots of runs and sags.... they dont come out as easily as you may think.... He will probably begin buffing and still see them and have to cut some more.

White Camero, this will be a judgement call for you since you have two different opinons... Take mine for what it is worth.

The cutting pad I was referring to is the Mirror Glaze Maroon foam pad # W7000... It is missing the 6 in the last part number because it is an 8" pad instead of a 6.5" pad... That is the difference...

When you buff, you will start to see the shine coming back... Continue buffing and adding in more compound etc... as needed until all of the sanding scratches are gone.... Easy way to tell this is sand in one direction, and when you buff, the scratches you will see from the pad and compound, will be swirl like marks...Toatally different from straight sanding marks...Feel Me??

Dont stay in one spot too long, keep the rpm's down until you get a feel for it.. This is not a race, and be very careful around the edges of the bumper... THis is where you are more likely to burn thru... Feel the panel everyonce in a while to make sure you are not creating too much heat too.... You can buff this thing all the way out with lower RPM's, it will take a bit longer, but you can still achieve the same results with less chance of burning through...

All paint has orange peel... It may not look like it because it is slicker than a factory paint job, but the texture is there and you will see it when you break the clear and begin sanding..

Another trick, once you have the panel sanded let it set out in the sun for a few hours.. What this does is draw out the tail solvents from under the paint... Bring it back into the shop and let it cool to room temperature and then buff... It will buff much better this way....


One last thing... No matter how easy you go, if there is allot of runs etc... you may not be able to sand them all the way out without hitting base... I dont care who tells you anything differently that is the facts.... The problem with sanding runs is you are also sanding the clear above and below it at the same time and wearing them thinner than the run... By the time you get through the run you may be too thin at the other area's...

They also make these little plains made to remove runs.. They are like 5 bucks or so at your paint store.... I think MG stores sell them too... They plane down the run just above the surface and then you wet sand... Or you can just use a single sided razor blade to knock off the top layers... You do this by scraping it down the run gently... you do not try and cut the clear... big no no..Look at this link, it will tell you how to prep the razor blade.. It is being used in a different application, but the prep for the blade is dead on.... http://home.comcast.net/~dcofer4/razor.wmv
... If you need more just ask


And By All Means do as SLD suggested and practice on the scrap panels... This will improve your skill and confidence at the same time.....


Matthew

[BondoKing]

http://www.repairnation.com/paint_n_bodywork/buffing/wetsand&buffing1.htm

http://store.yahoo.com/classic-motoring/problemsolving.html

[Five Star]

Originally posted by BondoKing
Who ever told you to not touch a bumper with a RB is just plain scared... I do it everyweek on something... No big deal, just a learning curve is all.

Not true

I've been using a RB for 22 years, I don't use them on bumpers,

however sometimes you need to use it as a last resort.

[BondoKing]

Originally posted by Five Star
Not true

I've been using a RB for 22 years, I don't use them on bumpers,

however sometimes you need to use it as a last resort.

If you cut a clear as he is going to do, you are wasting you time using that DA polisher to try and do what the buffer does...I know allot of you guys detail cars only, or on the weekends as hobbyist.... so doing what is standard can be scary for some

YOu been painting and cutting paint for 22 years?? If you have then you would be using RB's.

[Five Star]

Originally posted by BondoKing
If you cut a clear as he is going to do, you are wasting you time using that DA polisher to try and do what the buffer does...I know allot of you guys detail cars only, or on the weekends as hobbyist.... so doing what is standard can be scary for some

YOu been painting and cutting paint for 22 years?? If you have then you would be using RB's.

I use them everyday. maybe I'm not getting my point across

It's my preference not to use them on the bumpers unless I really need to ie: removing sand scratches

but its just my preference not because of being scared as you stated

[BondoKing]

I see it was the "scared" wording.. No offense meant there bro... I should have chosen better wording... In his, case with the sand scratches, he will need it.

Matthew

[Shiny Lil Detlr]

Originally posted by BondoKing
I know allot of you guys detail cars only, or on the weekends as hobbyist.... so doing what is standard can be scary for some

Granted. I do mostly just detail; though I HAVE done paintwork myself on some smaller parts/pieces, and touch-up of areas surrounded by OEM paint. So, maybe that makes me a bit more paranoid, but I've been doing it for 5+ years and have yet to ruin anything that mattered (practice panels are another story...)

The biggest trouble (especially when talking to folks on a forum like this) is that what works for someone who is used to working under certain conditions, may not work for someone else under separate conditions. Unfortunately it can be hard to judge what others are working with, or how much practical experience they have when it comes to specific tasks.

I find that it's usually better to err on the side of caution, simply because I hate when someone comes along with false hopes and is overly confident in abilities they've never actually used/practiced. While there certainly are some people who can pick up sandpaper and an RB and make magic without any trouble, most do need to start slow and "learn up to it." Jumping in off the deep end will not only teach you very quickly that you didn't know as much as you thought you did, but also will cause major damage requiring that an experienced pro be brought in to fix it.... which can get very costly.

Even at that, I know better than to think that I'm the best out there; I only have a little over 5 years of experience with this. Over the course of those 5 years though, I've been dedicated to educating myself about techniques/products/industry standards, and also to practicing for many, many hours on different naturally occurring and intentionally self-induced paint defects.

So again to the original poster, I urge you to start off on a small scale, using the least agressive compound(s) and sandpaper you can get... unless you truly have the practice time, knowledge, and skill to get more agressive with it. Over time you start to develop a sense for just how much a problem will need, and can skip some less agressive steps, but to start out you don't want to just assume and jump right in. Be realistic, and honest with yourself about your comfort level, experience, and skill level.