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EMI Shielding Spray for Hollow Body Bass/Guitar

Discussion in 'Pickups & Electronics [BG]' started by ANCIENTSOCIETY, Dec 7, 2017.



    May 18, 2016
    Las Vegas
    Hello everyone,

    I've been working on repairing a hollow body bass and a guitar, the guitar is finally finished. I was cautious about the feedback during a live setup in a medium size room with a 100W bass amp, 80W keyboard amp and my 80W guitar amp. Of course, when I would turn up the volume past a certain level, a crazy feedback loop ensued. I was looking online about shielding the cavity on a hollow body, and got plenty of responses including painting the inside with the black shielding tape, which doesn't seem like a bad idea. Then I saw this clear coat shielding spray online and thought, "Could I spray the outside of the guitar body with this and accomplish the same thing?"

    Precision EMI shielding | RFI shielding | ESD Shielding | Coating Services

    I know this is for industrial use I'm looking to see if there's any that comes in an aerosol can.

    I'm still pretty new to understanding the electronics side of electric stringed instruments, so I was wondering if this would work before I buy it and spray my guitars with it.

    Thanks y'all


    May 18, 2016
    Las Vegas
    Also i forgot to add, the guitar is an old TeiscoGenGakki ES330 copy, and i'm pretty sure the pickups aren't wax potted. The Bass is also an old MIJ hofner clone from the 60's and the pickups are newer chinese replacements but they also aren't wax potted. Would the wax significantly help fight the feedback even without shielding on a hollow-body? I'm guessing yes, but I want to know how much.
  3. byacey


    May 16, 2008
    Alberta, Canada
    Your problem is more likely acoustic feedback through the body and pickups resonating, not any kind of electromagnetic coupling. This is a purely tongue-in-cheek suggestion, but a better spray product for such problems would be expanding urethane foam.
  4. +1. Shielding will not do anything for the issue that was described.

    If you want to shield a bass, however, then copper tape is the most effective method. If you insist on a conductive paint, then StewMac's paint seems to be the standard. There are also a couple of other paints floating around eBay, etc. The website linked in the original post did not publish their price list, so I would assume you would be buying in large quantities. This may not be cost effective.


    May 18, 2016
    Las Vegas
    Thanks to both of you for fast reply. I was brainstorming the idea of the spray, but yeah that particular company looks like it only does wholesale. Im assuming the expanding foam spray be effective because it fills in the cavity.
  6. byacey


    May 16, 2008
    Alberta, Canada
    It would stiffen the hollow body and eliminate the internal air resonance, but it would probably destroy any resale value of the guitar.
    I often imagined expanding foam would cure some ill sounding saxophones too.:laugh:
  7. A real simple test that might prove it's acoustic feedback: Get a roll of that blue 3M Clean Release Painter's Tape (Home Depot, Lowes, Ace Hardware, etc.) and tape over the F-holes. This tape will come off cleanly when it's over, should not disturb the finish. If it knocks this down a few notches, there you are. Or you could stuff foam in the F-holes to try the same thing.
    DavC likes this.


    May 18, 2016
    Las Vegas
    Thank you very much. I will try it!
  9. charlie monroe

    charlie monroe Gold Supporting Member

    Feb 14, 2011
    Buffalo, NY
    Off topic, but if I were you, I would change out that avatar.

    TB is proud of being family friendly and your avatar definitely isn't.

    Be proactive before a Mod causes you to be reactive.


    May 18, 2016
    Las Vegas
    I didn't know, so thank you for letting me know, and I'm glad to hear that. My GF hates it when I'm on other forums like Seymour Duncan etc. because they aren't family friendly.
    charlie monroe likes this.
  11. 96tbird

    96tbird PLEASE STAND BY

    Do like the late great Malcolm Young did to his Gretsch’s. stuff it with socks. Totally reversible and very effective damping of harmonic feedback.

    I imagine if you filled the area from top to back along the Center of the cavity from neck to tail that would suffice and you wouldn’t see it through the F holes. (Excuse the following highly technical language) Use long heavy wool winter socks in pairs rolled over each other to form thick long sausages and stuff them in through the pickup routes.

    Shielding is for RF elimination. You are experiencing harmonic feedback.
    Last edited: Dec 7, 2017
    ANCIENTSOCIETY likes this.
  12. micguy


    May 17, 2011
    While expanding foam might actually help (if you could control it), and while you're just joking, I'll throw in an explicit caution to not consider it - the minimal expanding window version of Great Stuff might not destroy your guitar, but then again, it might. The regular Great Stuff (which expands a lot) is definitely capable of destroying a hollow body guitar - the force that stuff generates is pretty astounding.
    BlueTalon likes this.
  13. BlueTalon

    BlueTalon Happy Cynic

    Mar 20, 2011
    Spokane, Washington
    Endorsing Artist: Turnstyle Switch
    If he doesn't really care much about the bass, it could be entertaining for him to do a time lapse video squirting a bunch of that stuff in there.

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