If you are using a base coat/clear coat metallic paint, can the metallic base coat be block or even wet sanded prior to the clear? Or will it change the reflective qualities of the metallic particles were it was sanded?
Why do you want to sand it? If there was a problem, I'd sand it, but you'll have to recoat to get a uniform look to the metallic.
if you want to sand it because of runs or dirt, just re shoot the color after you sand it, then clear it.
why do you want to sand it?if it looks good but has some orange peel dont worry about it,just clear it a couple times{i like to do at least 4 coats}then you can make it smooth buy wetsanding the clear.
At this point I am going to say that you should wet sand it, most base is only good for 24 hours. Wet sand with 1000 grit, re-spray the base, and clear.
you really need to clear right away after the base. there is a certain window in which you can clear it without sanding. different products have different windows. the tech sheets from the product your using should have the recoat information on it. if your getting serious orange peel in your base you might want to play with your air pressure and the controls on the gun untill you are not. you might also try not laying it on quite so heavy. the last thing you want to do is sag your base coat anyways. get that clear on it in the proper amount of time. i'd say at least 3 wet coats, maybe 4 depending on how heavy you put it on and how smooth you plan on sanding it. then wet sand it starting with 1000 grit and ending at 2000 or 2500. then you start polishing from there. there are different types and grits of polishing compound and different pads to use with each. your gonna want to do your homework. P.S. when wet sanding be careful around any edges and use caution when sanding out sags. it's real easy to get carried away and sand through right next to the sag your trying to get out.
you don't state why you need to sand the base. it's pretty hard to run or orange peel base coat, but if it's uneven (blotchey), you need to put on drop coat on it to cover the stripes, not to dry though, because you can model the paint (bumpey looking under the clear). if you just need to de-nib it, scuff it 1000 grit and then recoat it and then drop coat it. most basecoat reducers are pretty aggresive, so unless you have some major issues, 1000 grit should be o.k. to sand with, and still not worry about adhesion. read the label for flash times at the temperature your spraying, and clear it. good luck.
Ed is right but in case you don't know what a "drop coat" is it's basically when you drop the air pressure coming into the gun. you should typically be using one as your final coat of base with metallic paint jobs. it helps to lay the metallic on evenly. ...i'm sure it's too late now but you should try the new waterborne base coats. pretty easy to fix screw ups and REAL hard to sag or orange peel the base if your doing it right. your supposed to spray the base on pretty dry (especially compared to solvent borne bases and clear coats). it also dries to the touch in pretty short order (time is dependent on air flow) and can be "denibbed" as soon as it is dry. If you have a major screw up you can actually wash the base right off the panel if need be.
The reason I was asking about sanding it was that I was hoping to add some simple graphics on top of the base, then clear over the whole thing. I just not sure of the exact process. Are you supposed to lay down the base then clear it. Lay down graphics, then clear it again.
You can lay out the graphics on the base within 30 minutes or so of shooting it. Or you can give the base coat a couple of quick coats of clear, wait a day and wet sand it. Then lay out the graphics and re clear it.
I move pretty slow when it come to masking off lines and stuff. I like the idea of shooting it with clear and then waiting a day so that I am not rushed.
If it's going to require other elements added I would think Chris 57 would be the way to go IMHO. Good Luck
base coat is very soft and not durable to tape to etc...clear it a couple coats then do your graphics, you'll be glad you did....I made the mistake of laying out scallops over bare base so they'd all be under clear and have an example of what not to do...oh well
You can A. tape on your basecoat (but risk tape lines and losing your window) B. Base then intercoat clear (risk nothing, tape graphic same day, scuffable if need be) C. Base and real clear (pointless) I vote B.