Register now to get rid of these ads!

Technical blocking high build primer with 3m pads. (curved surfaces)

Discussion in 'The Hokey Ass Message Board' started by wearymicrobe, Aug 5, 2020.

  1. wearymicrobe
    Joined: Jul 27, 2007
    Posts: 260

    wearymicrobe
    Member
    from San Diego

    I am working on rebuilding a 50's road race car it's a mix of metal and fiberglass construction. Car was stripped of paint, metal/glass is straight and it was sealed and sprayed with 3 coats of high build. It was knocked down with 150 and is ready for finish sanding before base coats.

    So my question is, this thing has about 4sfq of straight body panels on it and everything else is curved or a gentle valley. Getting in and block sanding this thing at least the way I would do it in the past is all by hand or 1/4 inch rubber is going to be difficult to keep consistent side to side. A local old painter suggested using 3M grey and red pads (400/600 grit equivalents) by hand as an alternative to blocks and paper. This car is going to get raced and its going to get hit and repaired a bunch so this is not going to be a 10K in material job but I want the basis done right.

    1. Has anybody done this successfully.
    2. Is there a block that conforms to valleys that you like if this will not work that will hold its shape or that is adjustable with like a truss rod?
     
  2. flamedabone
    Joined: Aug 3, 2001
    Posts: 4,808

    flamedabone
    ALLIANCE MEMBER

    These little things work great. They have metal rods that you can add or remove depending on the flexibility you need.

    https://sites.google.com/site/pomon...-adjustable-flexible-sander-sanding-block-kit

    And, I love these sponge pads.

    https://www.ottofrei.com/3M-Sponge-Sanding-Pad-10-pc-Assortment_3

    The trick is not to use them on anything but a small or curved surface and always finish with the superfine or ultrafine to avoid any sand scratches. If you can fit a block into the space you are sanding, it is better to do so.

    Good luck and post lots of pics.

    -Abone.
     
    Blues4U and loudbang like this.
  3. anthony myrick
    Joined: Sep 4, 2009
    Posts: 6,143

    anthony myrick
    Member

    I use paint sticks.cut all different sizes
     
    Blues4U, Splitbudaba and belair like this.
  4. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 2,670

    Lloyd's paint & glass
    ALLIANCE MEMBER

    I use these. I wrap my sandpaper around them. Works great. Use them almost daily. Lowe's or Ace hardware. They are sandingsponges 14340_media_1.jpg
     

  5. ScotchBrite pads on a car thats going to be a 50/50 car is fine or getting banged up all the time where you dont care about the finish... Give the paint some kind of edge to stick to.... And use water with it WET SAND.
    If you going to care about the finish you should NEVER sand with just your hand it can and will leave finger grooves, Always some kind of block between your hand and the sand paper.. For a good smooth surface.
     
    Blues4U and Jim Bouchard like this.
  6. Mr48chev
    Joined: Dec 28, 2007
    Posts: 27,508

    Mr48chev
    ALLIANCE MEMBER

    A few years ago there were some local kids with a paint shop here in town that had no clue as to what a long board or sanding block of any kind was. Hit it with the DA, throw on several coats of primer and sand that bare handed leaving smooth waves down the side of the car. Thing was the guy who sprayed the paint was a magician with a paint gun but his perfectly laid paint showed every ripple in the all too suspect prep job. You need a firm backing behind that scotch brite or any other abrasive material that you hand sand with.
     
  7. mark latham
    Joined: Oct 24, 2018
    Posts: 104

    mark latham
    Member

    Cardboard folded over on itself to the size you need also works well.
     
    Blues4U likes this.
  8. gene-koning
    Joined: Oct 28, 2016
    Posts: 2,011

    gene-koning
    Member

    The paint sticks covered with sand paper were life savers on the coupe. flexible enough to conform to the body curves, and long enough to keep a smooth surface. It would have come out really well if I could have handled sanding on it another week or two, but I couldn't. Gene
     
    Splitbudaba likes this.
  9. Fortunateson
    Joined: Apr 30, 2012
    Posts: 3,409

    Fortunateson
    Member

    I use a lot in the same way and without sandpaper to knock some of the excess filler off when I begin sanding.
     
  10. 6-bangertim
    Joined: Oct 3, 2011
    Posts: 385

    6-bangertim
    Member
    from California

    Mack your own sanding blocks from foam packing material!
     
    Sporty45 likes this.
  11. Just buy a couple blocks for God’s sake..scotchbrites are a surface prep disc...ie adds tooth for the next finish to grab on to..not much of a flatner due to their construction...prime it and get a block and some
    P400 and have at it...
     
    reagen and Asphalt Angel like this.
  12. indyjps
    Joined: Feb 21, 2007
    Posts: 3,919

    indyjps
    Member

    I would not use scotchbtites to level a surface.

    The pad will scuff, but just float over any waves leaving them there.
    Try paint sticks, body filler spreaders, wrapped with sand paper. Ive used heavy plastic cutting boards cut into strips for a backer. Sand in a 45 degree pattern across the curve, switch the pattern. If you use fresh paper it cuts fast.
    Curved blocks are worth the money, holding onto a paint stick for a long tine your hands will feel terrible.
     
  13. indyjps
    Joined: Feb 21, 2007
    Posts: 3,919

    indyjps
    Member

    Sanding sponges. I use them a lot in prep, not to block paint. They'll barely get drywall flat, I dont want to risk a paint finish on them.
     
  14. railcarmover
    Joined: Apr 30, 2017
    Posts: 498

    railcarmover

    [​IMG]

    Had some flaws on the first coat so I let it set for thirty days and hand sanded it with 1000 grit scotchbrite (grey) before reshooting it. Its just a homebuilt A bone,looks fine to me.
     
  15. KJSR
    Joined: Mar 7, 2008
    Posts: 2,298

    KJSR
    ALLIANCE MEMBER
    from Utah
    1. Utah HAMBers

    That's a great idea!
     
  16. wearymicrobe
    Joined: Jul 27, 2007
    Posts: 260

    wearymicrobe
    Member
    from San Diego

    Thanks guys. I will be using a backer of some type I have made the mistake of sending with my hands before and I don't want to repeat that.

    I think I am going to get some of those flexible sanding blocks.

    Been digging on the site and a few people have recommended the "Holy Terror" and Wonder Block so I ordered those up from Amazon tonight.

    Going to try the pads backed on the holy terror on a test panel. They may just be better for keying surfaces but it was worth a asking the question for future reference.
     
  17. Darin Younce
    Joined: May 8, 2019
    Posts: 576

    Darin Younce

    I like these as well, pretty good combo of firmness and flexibility.
     
  18. Darin Younce
    Joined: May 8, 2019
    Posts: 576

    Darin Younce

    I have used about everthing you can imagine over the years. One of my homemade pads is to take one of those 2×2 soft floor pads ( the type with a sorta dove tail locking edge and about 1/2 " thick) and cut it in different lengths and widths , works purty good for me on some things.
     
  19. wearymicrobe
    Joined: Jul 27, 2007
    Posts: 260

    wearymicrobe
    Member
    from San Diego

    How are all bodyman not like all upper arms and skinny.

    I am about 5 hours of sanding in and I have learned that I really enjoy body blocking. Just put on some music, have a drink and sand and sand and sand. My arms are killing me but it is not that hard. Just time consuming. I bet I have 40 hours of sanding to do even on this small little car to get it perfect. The holy terror is great as a sanding block but I ended up using some 1/4 inch rubber I had for some of the indents to test and that works much better.

    I did the hood in 220/360/600 and it looks amazing. Even with the powdered guide coat you cannot see any defects all the way through. I use 220 to knockdown any pinholes in the primer and then resprayed it with high build and let that sit overnight and guide coated the rest of the body with the powder.

    Seriously if you have the time and inclination this is not hard, though I have started looking at some of my other cars and I can see sanding marks under the paint when I look at it just right.

    So real dumb question, once I have a panel finished and I want to check it past using guide coating should I spray the panel with my base coat colored primer to see how I did or just leave it for later and paint everything at once and just trust the guide coat removal.
     
  20. Got any pics of the car? Sounds neat.
     
  21. wearymicrobe
    Joined: Jul 27, 2007
    Posts: 260

    wearymicrobe
    Member
    from San Diego

    Not exactly the most HAMB appropriate thing but bodywork is body work. Work has been extra slow and I have not been sleeping well so I go out and sand, and sand and sand.

    Right now its been 360 dry 400 wet then 600 wet sanded out. There is about three or four small pinholes on the body that I cannot seem to get my primer to stick to. Its like the sanding rips it out even after I let it dry for a few hours.

    The plan is to learn bodyshaping and replace things like the doors and the hood in aluminum eventually. I did paint about a 1 foot section of the hood with some really high quality spray paint and it laid out nice, only one sanding line that I missed and that was before I really went over it with the 600 grit again. I put some cheap clear on top and then the sanding line was not visible unless you got really down on the paint. But I had not buffed it out yet.

    Still need to sand the interior and all the jams and under the windshield once I remove it.

    The fiberglass is off yellow under the primer. So the black is the epoxy coat layer and the white is the TCL high build. No fiberglass is visuable from the sanding but there were definite high spots on the hood sand passenger fender.

    [​IMG]
     
    Blues4U likes this.
  22. Darin Younce
    Joined: May 8, 2019
    Posts: 576

    Darin Younce

    I have taken 3000 grit , put a few drops of water on the pad and sanded then sorts buffed dry, it will give you a pretty good shine and you can see if your ready for final steps to paint . Of course you will re sand that 3000 finish before painting or priming or whatever.
     
  23. Splitbudaba
    Joined: Dec 30, 2014
    Posts: 409

    Splitbudaba
    Member

    When I did my old 63 Vette I used paint sticks, tried holding the stick underwater overnight with weight. Made them more pliable, followed double curves more easily. When finished I won many best paint and class awards. One drawback, no finger prints left on my fingers!
     
  24. Blues4U
    Joined: Oct 1, 2015
    Posts: 4,867

    Blues4U
    Member
    from So Cal

    You know, that thing would look great with a small block V8 and Weber downdrafts poking out of the hood. ;)
     
    Splitbudaba likes this.
  25. wearymicrobe
    Joined: Jul 27, 2007
    Posts: 260

    wearymicrobe
    Member
    from San Diego

    I have the webers, 44s with velocity stacks.

    Got the car fully sanded out, doors are off and its ready to paint. I am in California and I cannot for the life of me get the waterborne paints or the lov VOC paints to spray or even brush out right. I get horrible orange peel and I get weird coloration in the paint even with the flash times and reducers they recommend.

    I may have to send it out for paint to someone who has more experience with this stuff.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.