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new bass shielding

Discussion in 'Luthier's Corner' started by joeyl, Feb 24, 2008.


  1. When building a new bass, and using shielding paint, should I finish the cavities first then apply shielding paint? or apply shielding paint to the bare wood? I have never shielded an unfinished bass before :rollno:
     
  2. kevinmoore73

    kevinmoore73 Supporting Member

    Jun 18, 2007
    Cleveland, OH
    I've never built a bass before, so take this with a grain of salt: If it were me, would probably do a rough job of finishing the cavities and then apply the shielding paint to that. Also, if it were me I would use copper foil instead of shielding paint.

    I've got five coats of shielding paint in my Lakland, with copper foil on top of that. (Yeah, belt and suspenders as someone else here mentioned.) The paint just didn't cut it for me.
     
  3. scottyd

    scottyd Commercial User

    Nov 17, 2006
    Waco Tx
    Builder/owner Redeemer Basses
    +1 I prefer copper or aluminum tape over the paint.
     
  4. Greenman

    Greenman

    Dec 17, 2005
    Ontario Canada
    Any cavity should at least be sealed some way IMHO. Shielding paint is water based and the moisture of the adhesive could wick to the wood.
     
  5. Suburban

    Suburban

    Jan 15, 2001
    lower mid Sweden
    I disagree with greenman. The shielding paint will work as a finish, the added moisture will leave soon enough. It will not in any way disturb the wood.
    If you apply a finish before the shield, you will jeopardize the adhesion of the shield. In my book, thin as it is, that is just as much worse as it is likely = pretty much.
    And - do the shield before any finish at all.

    I too prefer the copper tape...
     
  6. so does the water content from carpenter's glue :eyebrow:
     
  7. ok, so shielding then finish, got it. Thanks for the replies
    I like copper tape too, but I have had an instance where the copper separated from the adhesive backing, and touched the output jack :rollno:
     
  8. rwelcome

    rwelcome

    Jan 26, 2005
    Shielding paint can wick moisture into the wood via an un-finished hole or route, unlike glue shielding is usually done at the end of the build right before wiring, or as a improvement repair, thus if water based shielding gets to raw wood under the lacquer swelling can occur and it can mess up the lacquer by distorting it or cracking it. I've seen this happen to others and it's not pretty. Options? Well you can either check for bare holes and if you find any put some melted wax on them with a fine tipped brush, then apply the shielding paint (if adhesion is a worry take some 400 grit and rough up the area to be shielded, usually the paint has no problem adhering though), or do the Copper foil, which is my choice. It's pretty gratifying to see a nice coppery well trimmed cavity. Don't forget to have a small tab of paint or copper foil coming from the cavity making contact with the coverplate or pickgaurd shielding.
     
  9. rwelcome

    rwelcome

    Jan 26, 2005
    P.S. If you finish over the shielding (on top of it) it becomes useless. Maybe this is obvious?:meh:
     
  10. sorry, I meant finishing the rest of the bass :)

    besides it would still work provided there are lugs screwed into the shielding with wires going to ground, right :smug:
     
  11. kevinmoore73

    kevinmoore73 Supporting Member

    Jun 18, 2007
    Cleveland, OH
    Yes. I don't know why rwelcome says it would be useless.
     
  12. rwelcome

    rwelcome

    Jan 26, 2005
    Depending on the application, if you have finish over the shielding the backplate shielding can't make contact and won't close the shield. But whatever, just my thought on the matter. After 10 years of building basses I don't put finish over shielding.
     
  13. kevinmoore73

    kevinmoore73 Supporting Member

    Jun 18, 2007
    Cleveland, OH
    It's the "depending on the application" part that would make it useless, not the act of doing it. Of course it will cause problems if the finish is preventing something to be grounded that should be.
     
  14. kevinmoore73

    kevinmoore73 Supporting Member

    Jun 18, 2007
    Cleveland, OH
    Insulate your output jack with electrical tape or something non-conductive. That way, if the foil makes contact with the jack it won't matter.
     
  15. Greenman

    Greenman

    Dec 17, 2005
    Ontario Canada
    I didn't explain myself very well. I was less concerned about the effect of moisture on the surrounding wood and more concerned about too less moisture in the shielding. Same thing as a dry form sucking too much moisture out of cement. Probably no big deal tho. :)
     
  16. SDB Guitars

    SDB Guitars Commercial User

    Jul 2, 2007
    Coeur d'Alene, ID
    Shawn Ball - Owner, SDB Guitars
    Shielding paint, IIRC, is mostly carbon (graphite, etc.) in a binding suspension. It can be messy as hell, but it doesn't hurt the body wood at all, and you just brush it on... easy application. It makes for a nice, black, uniform look. On the plus side, it is *very* thin. Also, you just place a screw someplace in the side of the cavity (make sure it has good conductivity with the paint) and star ground everything to there.

    Copper foil applies fairly easily, too, although it is mode difficult to get into corners than the paint. When I started using it, it was recommended that you join the foil seams with solder, so that you ensure conductivity. As an aside, I generally make a "tab" of foil (soldered to the side of the cavity) for star grounding purposes.
     
  17. Greenman

    Greenman

    Dec 17, 2005
    Ontario Canada
    I have 5 coats of paint and some copper plate for attaching stuff. I run Big Singles and can solo either pup without any noise.

    100_1901.
     

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