Wet-sanding Instructions: How-to

Discussion in 'Color is everything!' started by xhp734, Apr 11, 2006.

  1. xhp734

    xhp734 Hearing the Voices again.

    It was a great idea to get the safety thread started. Along the same line of covering the essentials, can you guys with real wet-sanding experience provide us newbies with some instructions?
     
  2. Marvin's65

    Marvin's65 In progress :|

    Hey Dave,

    I dont have years of experience, but i recently wet-sanded my 70skylark. Came out really nice.
    I used 800grit paper and a lot of water.
    At the moment am fixing a fender that needs little detail work done on it. It's time consuming but it certainly pays off.
    Hopefully in 2 weeks i'll paint it, if it stops raining.

    :blast: Rain!
     
  3. MARTINSR

    MARTINSR Well-Known Member

    I have planned a "Basics" on color sanding but never have, there are lots of tricks.

    800 is actually pretty coarse, polishing out 800 scratches can be quite a chore.

    Here are a couple of tips:

    1. Get the car and the bucket of water CLEAN. I mean, CLEAN like you are going to drink the water out of the bucket and lick it off the car clean. A TINY speck of something under that 1000 grit paper, and you have 120 grit! Besure there is no dirt or grime that will wash out of nooks and crannies as you sand and rinse with water.

    2. You can start with something like 800 if you REALLY need to, but it is much better to start with a finer grit and then go down if you find it isn't cutting eoungh. 1000 or 1200 is usually plenty to get the job started then going up to 1500, 2000 and maybe beyond. :)

    3. Don't sand the edges. As you sand a flat part let the paper go off over the end of the panel or body line without really touching the edge. It will sand or buff thru very fast on the edge. So if you don't sand there at all, buffer will CUT there very easy so it will be cut flat without even trying.

    4. Don't sand all the orange peel off to perfectly flat with the first grit. Sand it down checking often with a rubber sqweegee (sp?) to see what you have. If you cut all the orange peel out you may not have enough material to cut remove the coarser grit scratches. You can always cut it more, but putting color and clear back, now that is a different story.

    5. Unless you have way too thin of clear, you shouldn't have a problem. Your typical clear coat is about 3.5 mils thick. We are talking JUST AS APPLIED in the tech sheets, usually just two coats are recommended of todays high solids clears. It needs to be 2 to 2.5 mils for proper protection. I did a check one time and found that a good cut and buff only removes .5 mil.

    6. DO NOT sand the whole car before buffing. So ONE panel and wet your feet, you need to understand just how much work it may be to do this. After doing that one panel, WASH THE CAR and start again (refer to number 1. :) )

    One final tip, get some Meguires color sanding paper. It is THE BEST BY FAR of any paper I have ever used! It costs a LOT more than 3M but lasts many times longer and its scratches are uniform and MUCH, MUCH easier to buff out. It cuts faster and it WAY easier to use.

    Brian
     
  4. Marvin's65

    Marvin's65 In progress :|

    Quetion Brian,

    Is this process for after paint sanding or after primer sanding?

    thanks for the tips

    :TU:
     
  5. 71stagegs

    71stagegs bpg member #1417

    wet sanding

    Put paper in bucket night before with some dishwashing liquid.It cuts a lot better.
     
  6. Truzi

    Truzi Perpetual Student

    How do you know when you have sanded enough?
     
  7. xtremepaint

    xtremepaint Mustang guy

    He is talking about color sanding the clear coat. Good advice too. :TU:
    And the way you know when you have sanded enough is by checking with the sqweegee. once it's dry, you will see if there is any oraange peel remaining. I use a dry method myself, so no sqweegee is needed to check
     
  8. 72 riviera

    72 riviera Marty Anderson

    good info! Has anybody here ever used a da sander with 1200 or 1500 to color sand? My paint shop sold me on a "new" system from 3M that uses a special pad for a da sander. It has velcro on it and then you put a foam pad about a 1/4" thick on top of that then 1200 paper disc. The process is 1200 dry, then 1500 wet or dry, then a special 3000 grit foam sanding disc wet, then a compound on a foam buffing pad, then a finishing glaze on the foam buffing pad. I recently jambed my car and tried it on the inside of a door. The system brought out the best results I have ever had buffing. I am painting the car black and there were NO swirls and it was like a mirror. My concern is I am scared to death of breaking through the clear and or base. I had a small ridge that I got a litte close to with the 1200 and it cut right down to the primer. It is effective but very easy to screw up a nice paint job. I know you are not supposed to go anywhere near any ridges or body lines with the da sander. It is much easier and faster than doing it by hand. I think if I only use the da on flat surfaces I should be ok. Would I be smarter to just do it all by hand and play it safe? All opinions would be appreciatted
     
  9. MARTINSR

    MARTINSR Well-Known Member

    Marvin, as mentioned, yes, this is for "color sanding" for buffing. It is called "color sanding" because that is what it has been called for years long before the popularity of basecoat clearcoat systems. So even though you are sanding clear, the term used (at least here in Cali-forn-ya) is "color sanding" when you are sanding a car to polish it. Also commonly called "cut and buff".

    Truzi, check it, check it, check it, as you are going. Dry or wet, CHECK IT and PAY ATTENTION. You will see the shiny surface of the clear (or paint if you are cutting and buffing a single stage paint with no clear) acts like a "guide coat". You can easily see what is cut and what isn't. Just STAY AWAY FROM THE EDGES you will sand those without even trying.

    Steve, I havn't done that since the lacquer days and have forgotten all about it. Sure, a little soap in the water is going to help lube the paper. And leaving the sand paper in the bucket over night (or at the very least a few hours before sanding) is one of those things I never did until I read the directions. :) It does help a lot.

    Darrin, 72riv, yeah, we now use the dry method as well. It really isn't that different or difficult but the learning curve is steeper. :) When I first tried it we were using Carborundum paper and they had a real thick foam (about 3/4") "innerface pad" that worked GREAT. I don't know why 3M doesn't use one like that. You could go right up to edges and curves without a problem first time using it.

    Anyway, I don't recommend the first timer to use it without personal hands on direction.

    Brian
     
  10. BillMah52

    BillMah52 Well-Known Member

    The thought of using a DA to color sand on anything but a clear makes the hair on my arms stand. Spend a couple o' K on paint and ooops with the DA?
    Nah!!!
    I'll just keep makin' my arms tired. :laugh:


    Brian - I still think you should put it all together and get youself published. :Comp:
     

Share This Page