Pickup/guitar Shielding...

[Chadheckler1]

My newest problem is related to what I believe is some sort of static buildup.

I just finished two Les paul style guitars from scratch and they both have this exact same problem (One with P-90s and one with humbuckers...both made by me).

The problem is I hear popping/crackling sounds when the guitar shifts or rubs on my pant leg (Standing and using a strap while playing). After removing the cover plate on the back I cannot find anything loose or wrong on the wiring inside...and furthermore when I rub my hand on the back of the body I can make it happen...none of the other guitars I have built have this problem.

I used mcfaddens lacquer on these guitars...as with many other guitars I have built that do not have this problem.

The coils on both pickups are shielded, P-90 with copper tape directly around the coild and the H-buckers with nickel silver covers.

I have not tried copper shielding tape in any of the cavities yet becuase I have never had the need before... Has anyone ever had this problem and do you think I am on the right track with shielding the cavities with tape/paint?

[belwar]

Heres a stupid question ... Do you have a ground from the stop tail or bridge to the pots? We use the mcfadden UV Poly and dont have this problem. It does sound like a shielding issue, but it shouldnt effect the guitar with buckers so much.. There really is not much point in copper taping the back of a bucker guitar, but it will make a difference on the P-90.

Why did you copper tape the pickups?

[David Schwab]

Putting a loop of copper tape around the coils can make them darker sounding... you need to keep the loop open.

It sounds like you have ungrounded shielding.

[David King]

It's static build up and there needs to be a path to ground for that to dissipate. Are the strings really grounded? You might need to give the back of the guitar a blast of negative ion air though I'm not sure how long that will last. Maybe wipe it with an antistatic drier cloth.

What's the relative humidity in the room? I'll bet it goes away with the RH above 40% If you like to wear polyester leisure suits on stage it could still be a problem.

Shielding the cavity never hurts so do that and tell us if it goes away.

[Chadheckler1]

I am in Michigan, in my basement and near my furnace when I play so I am sure the RH in there is below 40%...my project for the next available weekend is to install a furnace humidifier. But, even though my basement is less than 40%, it was not happening on any of my other guitars which is really baffling to me...and when I played it at a local pub last weekend it still had the problem at that location as well...and no, I was not wearing my grandfathers tan polyester suit, HA!

The Bridge on both guitars are definately grounded properly...

I Shielded the P-90s just for kicks... I had never done it before and wanted to give it a try. I ran a hookup wire from the copper shielding tape to the base plate...that was the right thing to do right?

Anyway, I think I will try shielding one of the guitars and see what happens, like king said it can't hurt...it could just be a waste of time. How about the paint? Does that stuff get the same results as the tape?

[David King]

I use nickel conductive paint from a spray can. The carbon paint is a joke.
Silver plated copper paint in another option but at $800/ gallon you won't use it up in time before it goes bad in 6 months.

[belwar]

I use nickel conductive paint from a spray can. The carbon paint is a joke.
Silver plated copper paint in another option but at $800/ gallon you won't use it up in time before it goes bad in 6 months.

Out of curiosity, why do you say its a joke? Im currently using the stuff from stew mac

[David King]

Belwar,

Please take a resistance reading between any two points of a painted surface and tell us what it is.

(My experience is that it's well above 1/2 ohm I get with the nickel.)

Also rub the surface with your finger, does it come off and generally make a mess?

If you stick down a copper foil pad and solder to it -does it stay stuck? Even after 10 years?

When stewmac ships via ground in winter, did the stuff freeze and arrive doa?

Does it keep in the jar for more than a year?

Does it cost less than $.50 per guitar for a full shielding job?

Does it stick to ABS plastic or glossy paint jobs?

Does it dry ready to go in 10 minutes or less?

Can you get by with one coat?

[Bruce Johnson]

I'll back up what David says. The Stew-Mac carbon type conductive paint is useless. It doesn't conduct well, it degrades over time in the can and in the guitar, etc. I don't know why they still sell it.

Copper tape shields very well but it's labor intensive to put in. You also have to be careful installing it, because pieces can come loose over time and short stuff out.

The best solution I know of is the Super Shield nickel-based paint in spray cans. That's what David was referring to. It's fast and permanent, and works very well.

[David Schwab]

Also rub the surface with your finger, does it come off and generally make a mess?

I hate that carbon paint! The big joke is when you see it painted on and not grounded! Fender loves to do that.

If you stick down a copper foil pad and solder to it -does it stay stuck? Even after 10 years?

Yes, actually past 28 years as demonstrated by some of my basses, like my Rics. I have a hard time peeling it off after all that time.

The nickel paint is very good, but foil is thicker and offers better shielding.

Ken Smith also uses the nickel paint.

[jonson]

Grounding paint????

Great stuff! just had a 6mth old tele in for rework and that was grounded in every cavity. Black wires and eyelets everywhere. Shielding paint NO NOT A DROP IN SIGHT. Been missed out completely. Good quality control Fender!!!!!

[belwar]

Very interesting!

I dont have alot of experience in shielding, so I just started with the stew mac stuff. Does anyone have a link to a good paint? Im not crazy about aerosols, but if I must then ...

b.

[Bruce Johnson]

The copper shielding tape that I have measures 0.0025" thick, including the adhesive. The copper foil itself is probably about 0.0015". I haven't measured it, but I'm pretty sure that two coats of the nickel Super Shield is several times that thickness. So, I doubt the claim that the copper tape provides better shielding, unless someone can explain otherwise.

I used the copper tape for many years on my basses. My biggest complaint was the amount of labor it took to put it in. The control cavities in my Scroll Basses are very complicated in shape. I had a few cases of the tape peeling up over time and shorting against the positive jack contacts. The adhesive on the tape is good on smooth surfaces like pickguards and paint, but it's not so good on bare wood or rougher painted wood. One trick I used to prevent the shorting is to put a layer of clear packaging tape over the copper in the area under any potential shorting targets.

Once I switched to the Super Shield, all those problems went away. I have a plywood masking template which plugs on to the body. I spray two coats about ten minutes apart, and then it's dry in 20 minutes. It's tough paint. Once it's cured, it's actually hard to scrape it off.

[mkat]

Another bad rap for that crap carbon paint. Where are you guys sourcing the nickel conductive paint?

[Chadheckler1]

Another bad rap for that crap carbon paint. Where are you guys sourcing the nickel conductive paint?

http://www.mgchemicals.com/products/841.html

Just did a quick search...is this the paint you are talking about? Looks like it comes in liquid and aerosol...has anyone tried the liquid? I think I would prefer to brush it on than spray it.