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Wet sand bonnet (hood)

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  • Wet sand bonnet (hood)

    Would like to do some wet sanding on the bonnet hood area this has been resprayed from previous ower by the looks of it..

    I can see a few dirt nibs would liked removed
    Also would like to reduce the OP just knock down the high spots of it..

    Been doing PTG readings and getting 98 micons near some of the edges the rest of areas im getting from 115 to 170 microns

    Could i use a p2000 Finishing disc and perhaps and interface pad as well would it be safe to do the job?

    Would the finishing disc be less aggressive then sanding by hand?

    Could i just use the p2000 disc then compund or would i have to go p2000 then 3000 then compund?

  • #2
    Re: Wet sand bonnet (hood)

    Here is a good article by Michael Stoops:
    The Power of 3000 Grit. https://meguiarsonline.com/forums/sh...r-of-3000-Grit
    Note that he mentions that hand sanding with 1500 can be more agressive than machine sanding.

    Comment


    • #3
      Re: Wet sand bonnet (hood)

      No worries thanks old bear

      Comment


      • #4
        Re: Wet sand bonnet (hood)

        If the panel has been resprayed and you're getting the PTG readings you are, it sounds like you've got a decent amount of paint on the panel. If it is in fact a respray then it sounds like it was a bare metal spray as those numbers aren't too far off what we'd expect to see from an OEM finish. What's perhaps a bit worrying here is that there could have been some isolated damage that required a full fix in a small spot where the color was blended, and then the entire panel was scuffed and fresh clear shot over it (you can't really blend clear, so this is a fairly standard practice).

        That said, 2000 grit on a DA sander, with an interface pad, isn't going to be terribly aggressive and, depending on the paint hardness, those 2000 grit marks should buff out pretty easily. I'm always a fan of refining the sanding marks as much as possible to make the buff out less invasive (ie, less chance of overheating the paint due to aggressive machine compounding). Orange peel reduction may be pushing it with that paint thickness, but if the texture is more of a dry spray or similar fine texture issue, then the process you describe might just be the ticket.

        The following was taken from an article dating back to our NXT Institute training session in 2014 Note that we started with even less paint than you have (roughly 90 microns) and we only used 3000 grit on a DA before polishing. This was also a respray, and a bad one at that. It's amazing the changes you can make to the appearance with very minimal paint removal.



        How's this for a little non invasive paint correction: this is on a rental BMW with a truly horrid respray on the rear of the vehicle. The paint had an incredible amount of texture and therefore almost zero clarity in the reflections (if you want to call it a reflection!). Two things to observe in the images below: A) the paint thickness readings showing the minimal amount of paint removed, in this case 0.05 mil which is virtually nothing, and B) the clarity of the reflection of the paint thickness gauge in the "after" shot on the right versus the "before" shot on the left. This level of correction was achieved with a 3000 grit finishing disc on a DA followed by M205 on a microfiber cutting pad. Yes, you read that right - M205 on a microfiber cutting pad.


        A "before" reflection on the same hood.


        An "after" reflection on the same hood, after using the steps described above.


        This may not be Facebook, but this is indeed a selfie, shot in the "before" of that horribly resprayed hood. How's that for texture and lack of clarity?


        Same hood, same process as above. How crazy is that?
        Michael Stoops
        Senior Global Product & Training Specialist | Meguiar's Inc.

        Remember, this hobby is supposed to be your therapy, not the reason you need therapy.

        Comment


        • #5
          Re: Wet sand bonnet (hood)

          Originally posted by Michael Stoops View Post
          If the panel has been resprayed and you're getting the PTG readings you are, it sounds like you've got a decent amount of paint on the panel. If it is in fact a respray then it sounds like it was a bare metal spray as those numbers aren't too far off what we'd expect to see from an OEM finish. What's perhaps a bit worrying here is that there could have been some isolated damage that required a full fix in a small spot where the color was blended, and then the entire panel was scuffed and fresh clear shot over it (you can't really blend clear, so this is a fairly standard practice).

          That said, 2000 grit on a DA sander, with an interface pad, isn't going to be terribly aggressive and, depending on the paint hardness, those 2000 grit marks should buff out pretty easily. I'm always a fan of refining the sanding marks as much as possible to make the buff out less invasive (ie, less chance of overheating the paint due to aggressive machine compounding). Orange peel reduction may be pushing it with that paint thickness, but if the texture is more of a dry spray or similar fine texture issue, then the process you describe might just be the ticket.

          The following was taken from an article dating back to our NXT Institute training session in 2014 Note that we started with even less paint than you have (roughly 90 microns) and we only used 3000 grit on a DA before polishing. This was also a respray, and a bad one at that. It's amazing the changes you can make to the appearance with very minimal paint removal.
          Yes im always amazed what 3000 grit can achieve.

          So if i use the 3m 3000grit sanding disc i should be safe with the ptg readings im getting?

          What speed setting do you recommend on the da?

          Comment


          • #6
            Re: Wet sand bonnet (hood)

            To help others answer your question, are you referring to the 3M Trizact foam sanding disc 3000 grit.
            The foam will help follow the paint texture contour, rather than remove it, like one of the non padded disc might do.
            https://www.detailing.com/store/3m-0...-in-p3000.html

            Comment


            • #7
              Re: Wet sand bonnet (hood)

              Originally posted by Old Bear View Post
              To help others answer your question, are you referring to the 3M Trizact foam sanding disc 3000 grit.
              The foam will help follow the paint texture contour, rather than remove it, like one of the non padded disc might do.
              https://www.detailing.com/store/3m-0...-in-p3000.html
              So use a trizact 3000 non padded disc then?

              Comment


              • #8
                Re: Wet sand bonnet (hood)

                Originally posted by Michael Stoops View Post
                If the panel has been resprayed and you're getting the PTG readings you are, it sounds like you've got a decent amount of paint on the panel. If it is in fact a respray then it sounds like it was a bare metal spray as those numbers aren't too far off what we'd expect to see from an OEM finish. What's perhaps a bit worrying here is that there could have been some isolated damage that required a full fix in a small spot where the color was blended, and then the entire panel was scuffed and fresh clear shot over it (you can't really blend clear, so this is a fairly standard practice).

                That said, 2000 grit on a DA sander, with an interface pad, isn't going to be terribly aggressive and, depending on the paint hardness, those 2000 grit marks should buff out pretty easily. I'm always a fan of refining the sanding marks as much as possible to make the buff out less invasive (ie, less chance of overheating the paint due to aggressive machine compounding). Orange peel reduction may be pushing it with that paint thickness, but if the texture is more of a dry spray or similar fine texture issue, then the process you describe might just be the ticket.

                The following was taken from an article dating back to our NXT Institute training session in 2014 Note that we started with even less paint than you have (roughly 90 microns) and we only used 3000 grit on a DA before polishing. This was also a respray, and a bad one at that. It's amazing the changes you can make to the appearance with very minimal paint removal.
                Mike that post you were referring to were u using a megulars 3000 finished disc?

                So should i use a non padded disc and no interface pad or will using an interface pad be ok?

                Comment


                • #9
                  Re: Wet sand bonnet (hood)

                  Originally posted by xrmte View Post
                  Mike that post you were referring to were u using a megulars 3000 finished disc?

                  So should i use a non padded disc and no interface pad or will using an interface pad be ok?
                  We used a 3000 grit finishing disc (built in thin foam) and an interface pad. We normally recommend use of the interface when doing paint correction rather than texture leveling, but if your plan is to level texture then you'd want to skip the interface pad. Just be very, very aware of any contours, great or small, when doing so. Especially if you have no prior experience!! Wet sanding, when done right, can be very non-invasive to the paint due to the lack of heat from heavy compounding. But it can also bite you pretty quickly if you're not paying attention.

                  As for speed settings on the DA, stick with roughly 3 to 4 on the speed dial, depending on the tool. You want pad rotation, but it doesn't have to be spinning really fast. In fact, too much pad spin and too much water can cause you to hydroplane and lose cut. If you do lose spin you'll still cut because it's sandpaper, so pad rotation isn't quite as critical as when polishing paint. Just use the weight of the tool and let the abrasive do it's job. Oh, and 3M Trizact etc are really more of a damp sanding process - no need to soak the discs in water first, and no need to flood the surface with water. A couple trigger pulls of a spray bottle, both onto the paint and onto the abrasive disc is all that's needed. As you see residue start to build on the disc, clean it thoroughly by spraying water on it. This is critical to avoid pigtails.
                  Michael Stoops
                  Senior Global Product & Training Specialist | Meguiar's Inc.

                  Remember, this hobby is supposed to be your therapy, not the reason you need therapy.

                  Comment


                  • #10
                    Re: Wet sand bonnet (hood)

                    Originally posted by Michael Stoops View Post
                    We used a 3000 grit finishing disc (built in thin foam) and an interface pad. We normally recommend use of the interface when doing paint correction rather than texture leveling, but if your plan is to level texture then you'd want to skip the interface pad. Just be very, very aware of any contours, great or small, when doing so. Especially if you have no prior experience!! Wet sanding, when done right, can be very non-invasive to the paint due to the lack of heat from heavy compounding. But it can also bite you pretty quickly if you're not paying attention.

                    As for speed settings on the DA, stick with roughly 3 to 4 on the speed dial, depending on the tool. You want pad rotation, but it doesn't have to be spinning really fast. In fact, too much pad spin and too much water can cause you to hydroplane and lose cut. If you do lose spin you'll still cut because it's sandpaper, so pad rotation isn't quite as critical as when polishing paint. Just use the weight of the tool and let the abrasive do it's job. Oh, and 3M Trizact etc are really more of a damp sanding process - no need to soak the discs in water first, and no need to flood the surface with water. A couple trigger pulls of a spray bottle, both onto the paint and onto the abrasive disc is all that's needed. As you see residue start to build on the disc, clean it thoroughly by spraying water on it. This is critical to avoid pigtails.
                    Thanks mike great information
                    I would like to reduce the op texture so as you said use the 3000 finishing disc without the interface pad

                    Do you know many mils could be removed when just using the finishing disc straight on the backing plate?

                    What would be a safe PTG range reading to use these discs to reduce op where is the limit?

                    Comment


                    • #11
                      Re: Wet sand bonnet (hood)

                      Originally posted by xrmte View Post
                      Thanks mike great information
                      I would like to reduce the op texture so as you said use the 3000 finishing disc without the interface pad

                      Do you know many mils could be removed when just using the finishing disc straight on the backing plate?

                      What would be a safe PTG range reading to use these discs to reduce op where is the limit?

                      Well, if this was factory OEM paint I'd tell you the general rule of thumb is to not remove more than 0.5 mil (13 microns) of the topcoat. But since this isn't OEM paint, all bets are off. You have no real info on just how thick the topcoat is, so proceed with caution. That said, you can see the tremendous improvement we made with even less material removed than that, so with minimal impact to film thickness you can do wonders with texture removal.

                      I'm guessing it's a safe bet that the rest of the car's OEM paint has some orange peel to it as well - they all do in varying degrees. Going easy with the sanding at first will help you match that texture so that the hood doesn't look out of place by being too flat, instead of too textured. That's easier, and safer, to achieve than trying to make it dead flat.
                      Michael Stoops
                      Senior Global Product & Training Specialist | Meguiar's Inc.

                      Remember, this hobby is supposed to be your therapy, not the reason you need therapy.

                      Comment


                      • #12
                        Re: Wet sand bonnet (hood)

                        Originally posted by Michael Stoops View Post
                        Well, if this was factory OEM paint I'd tell you the general rule of thumb is to not remove more than 0.5 mil (13 microns) of the topcoat. But since this isn't OEM paint, all bets are off. You have no real info on just how thick the topcoat is, so proceed with caution. That said, you can see the tremendous improvement we made with even less material removed than that, so with minimal impact to film thickness you can do wonders with texture removal.

                        I'm guessing it's a safe bet that the rest of the car's OEM paint has some orange peel to it as well - they all do in varying degrees. Going easy with the sanding at first will help you match that texture so that the hood doesn't look out of place by being too flat, instead of too textured. That's easier, and safer, to achieve than trying to make it dead flat.
                        Thanks mike so in my situation just to recap what sanding disc should i aim for?
                        And use with or without interface pad?

                        Comment


                        • #13
                          Re: Wet sand bonnet (hood)

                          Definitely start with a 3000 grit finishing disc, with the interface pad, and proceed cautiously from there depending on result.
                          Michael Stoops
                          Senior Global Product & Training Specialist | Meguiar's Inc.

                          Remember, this hobby is supposed to be your therapy, not the reason you need therapy.

                          Comment


                          • #14
                            Re: Wet sand bonnet (hood)

                            Originally posted by Michael Stoops View Post
                            Definitely start with a 3000 grit finishing disc, with the interface pad, and proceed cautiously from there depending on result.
                            Ok thanks mike will have to order some soon I'll let you know how i get on.

                            Comment


                            • #15
                              Re: Wet sand bonnet (hood)

                              Originally posted by Michael Stoops View Post
                              Definitely start with a 3000 grit finishing disc, with the interface pad, and proceed cautiously from there depending on result.
                              Ok mike done a ptg reading on the boot (trunk) which is 3.8mils and 4.0mils and thats fairly consistent on that whole area

                              If i use the 3000 finishing disc and the interface pad say 5mm or 10mm pad?
                              It should only remove about 0.05 -0.07 mils correct so I'll still be in the safe zone?

                              Comment

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