I realize this is a real noob question, but I've never wetsanded anything and I'm looking at trying to paint my mom's old escort. How do you do it? Thanks for any help.

 

Only stupid question is one never asked. Wetsanding uses sandpaper designed to sand when wet(often called wetordry). You keep the surface wet with a running hose or a clean bucket of water and sponge to both help sanding and to keep underneath the paper clean. Some people like to use a drop or two of dishwashing soap in the bucket. I haven't ever had any problems with joy, bu t had heard of a few instances where using dishwashing soap has led to fisheyes in the finish. You want to keep paper clean and water flowing underneath. If you get dirt and debreis trapped under the paper, It can make for nasty scratches. In bodywork, wet sanding is most often used for final sanding of primer, and color sanding after paint to knock out dirt nibs and defects prior to buffing it out, or when going to be doing a repair, blend of color(base on a panel, and clearing that panel. I personally like final sanding my primer wet, as I think its easier to see whats going on when sanding off guide coat, and I also like to color sand wet. Its the way I learned to colorsand. I think wetsanding does a better job for me, and paper lasts longer. Everyone has there own methods of how they prefer to procede and do there sanding. Years ago pretty much everyone wetsanded by hand for color sanding prior to buffing. Now many will actually use the correct orbital palm sander, pads and dry paper. They make dry papers really fine now, and have special pads. Each method of sanding has its plus and minuses. Wetsanding makes a lot of sludge to clean up, makes you hands fingers wrinkle up soaking in water, and may end up with wet shoes and pants standing in a puddle, LOL. Wetsanding also usually can sand epoxy primer easier or if you have a flaw in your basecoat to remove and hit with some more color cab usually wetsand after about an hour, whereas dry may smudge it and ball up on the paper. Dry sanding makes a lot of dust, the dust drys out your skin. Its best to use a dust mask when dry sanding and creating dust. You shouldn't ever wet sand bodyfiller, it will soak up water and thats not good, especially if there is baremetal underneath. If bodyfiller gets wet, make sure all the moisture is out before applying anything over it. I believe also years ago they advised against wetsanding lacquer primer for the same reason. Lacquer primer doesn't provide the best protection to bare metal, and believe the reason advised against is same thing, moisture reaching baremetal underneath. Epoxy primer is really the only primer that is non porous, but a lot of people wetsand urethane primer. But having a coat of epoxy over baremetal is usually the best, has good adhesion and will provide a moisture barrier underneath. Filler work can be done over epoxy primer. The tech sheets for the paint you use should give you final sanding grit range prior to paint, weather you want to do it by wetsanding, dry, or by machine. 320 dry by machine is about equavilent to 400 wet. Handsanding dry by hand produces a courser scratch then by machine. Color sanding prior to buffing, usually start with 1000 to 1500 wet depending on imperfections to remove, and get down finer at least to the 1500-2000 range. Normally you try to start the finest that will still do the job of removing the inperfections you have. 600 is the coursest you should go when colorsanding and then should only be used in extreme situations like removing a decent sized run, and pray you don't break through your clear into base. The finer you go colorsanding the easier it will be to bring back the gloss and remove scratches with the buffer. If sanding down old paint and plan on sealing or painting over that, dry sanding with an orbital palm sander is usually the easiest way. As long as you keep it flat or avoid digging in or making the surface wavy. The orbitals by dyanbrade and hutchins for example, sand so much smoother for finish sanding then the old da (dual action) sanders did. A da still can be used to sand, but harder to keep it flat and from jumping around without some experience sanding with it. If you sand by hand, you will most likely want to use a foam backup pad or some type of sanding block, If you do sand with your hand, keep your palm and fingers flat and sand with hand flat, sanding with just finger tips can create grooves that you will see when painted. I hope all my rambling helps you with any questions you have about sanding.

 

If you're painting you don't have to wet sand. Use a "D/A" (dual action) sander and 180 -220 grit sandpaper. That will save you alot of time. Hold the pad of the sander flat or you'll gouge the serface creatting an "*********" and that's more to fix.
Sand the edges of trim, door handles, glass etc by hand using the same paper. You just need to get the gloss off the paint, don't need to go to bear metal.
Bob

 

wow 180-220 before painting?? is this a refrigerator? shurly not any vehicle that might come in contact with humans. Ikk!

 

Kenseth17 explained wetsanding very well. I would just add that using a hose is good, but I went down to HD and got a big spray bottle and filled it with water. I then use it to constanting spray on the area that Im wetsanding. It sort of helps with your water bill. I also keep a bucket of water near me and dip the sandpaper in it. It helps keep the paper clean and will make it last even longer. I really enjoy wet sanding epoxy primer.


Matt

 

Thanks for posting this. I had the same question but hadnt posted it yet. Great information on this site.

 

Funny, I have been doing that to my truck this summer. I don't know what kind of paint you are using, but I did spray paint (I know, not the best) It turned out good, but not really reflective. I tried wetsanding once about 2 years ago, but it didn't help because I didn't know what to look for. Here's what it looked like before:

When you wetsand, it needs to go until it looks scratched, but ABSOLUTELY NO shiny dimples. Once you are there, then buff to shine. On mine, the clearcoat "juice" is whitish, and if I go through, it will be green. Just keep that in mind. I was scared the first time because of the "juice". Here's what the difference can be:



Good luck!

 

Thanks a lot everybody, especially kenseth (go 17)!. I'll post a pic if I ever get this thing done.