Pickup/guitar Shielding...

[salvarsan]

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

The old Ovation Deacon had .01" brass sheet for shielding, more like a brass can.
No worries about it sticking to the cavity since it was solid and form-fitting.

-drh

[SteikBacon]

yeah come on guys. can you tell me where to look for it then I too try out this. Threw away the carbon I had and are tired of mounting cobberfoil.

[David King]

The price of nickel went through the roof with all the other metals last year so you might hunt around for your best price, I used to get it for $20 a can now I see $33 as the typical price.
I just got 5 cans here in December but the price might be dropping as we speak at some other store.
http://www.elexp.com/che_5944.htm
This place seems like a mom and pop operation, kinda slow but it did come. I'd call for faster service, I think they check web order about once a week. Their number is 800-972-2225

[Joe Gwinn]

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

Carbon paint, even the good stuff, has too high a resistance to be much help. The super shield nickel-plated copper dust paint for MG Chemicals works far better. The basic trick when spraying the cavity in a guitar is to do it from all directions around the cavity, so the sidewalls get well covered.

If you have done well, an ohmmeter will show no more than ten or twenty ohms between probes, no matter where those probes are put. This is a short circuit for an electrostatic hum field, but has no effect on a magnetic hum field. But don't worry -- even a box made of soldered copper sheet has no effect on a magnetic hum field, so there is no point in worrying about that.

[Chadheckler1]

I am thinking of buying a bottle of the liquid super shield ($135 for 900ml is the smallest that it is sold) Anyone interested in 1/2 of it? I don't think that I would use that much in 5 yrs!

[belwar]

I am thinking of buying a bottle of the liquid super shield ($135 for 900ml is the smallest that it is sold) Anyone interested in 1/2 of it? I don't think that I would use that much in 5 yrs!

Yeah send me a PM - I'll do half or 3/4 if you want.

b.

[Joe Gwinn]

I am thinking of buying a bottle of the liquid super shield ($135 for 900ml is the smallest that it is sold) Anyone interested in 1/2 of it? I don't think that I would use that much in 5 yrs!

Shake well before dividing or using. It settles. Also stir or shake from time to time if not used, or the metal dust will end up in a lump.

Also, keep in a well-sealed glass or metal bottle, so it doesn't dry out too fast.

[David King]

Trust me guys, you probably don't want to use this stuff out of the bottle unless you are going to be producing hundreds of guitars a month. Once you open it, it will start to skin over immediately. It is formulated to be sprayed with special spray equipment that has an agitator to keep the heavy particles in suspension. This stuff is also VERY smelly, you don't want it open in your house. It's also extremely volatile so you can't expect to dip a brush in it repeatedly and not have it turn into a thickened, gummy mess in no time. You would be penny-wise and pound foolish to think you are getting a better deal with this format. It will just go to waste.
I get between 30 and 50 applications from a spray can and go through about one can a year.
Get yourselves a 3M masking paper applicator with 6" paper and mask your instrument first. Even with masking and spraying it's still quicker than a brush or copper tape.

In the photo below I managed to get overspray onto this reissue's lacquer finish and it melted right in. I had to buff it out

[mkat]

Thanks for the sources and the application details David. How many coats are necessary for a cavity?

[David King]

One coat has been plenty but two coats might get you 1% better shielding. I do two coats around pot holes where the serrated lock washers may grind away the paint over time. It flashes off so quick that you can re-coat an area in a matter of a minute or so in the same session.

It's important to follow basic spraycan hygiene. Shake the can vigorously for 30 seconds before and every 5 seconds during the session.
Hold the can upside down at the end of the session and spray until the draw tube clears out the paint.
Wipe down the nozzle and drop the nozzle into a thimble of lacquer thinner or acetone. I squirt a drop of acetone into the top of the draw tube and reinsert the nozzle before putting it back on the shelf and I've never had a clog since.

[Joe Gwinn]

One coat has been plenty but two coats might get you 1% better shielding. I do two coats around pot holes where the serrated lock washers may grind away the paint over time.

Dip the washer in the coating paint and install wet.

[Bruce Johnson]

Here are two quick shots of one of my Scroll Bass bodies as I'm spraying the shielding. You can see how complicated the cavities are, and why it was such a pain to do in copper! The masking template is made from 1/4" MDF and plugs into two reference pin holes in the body. Two coats is all it takes, about 10 minutes apart. I spray the shielding after the base coats (which are clear) and before the color coats. The cavities are masked off while the color coats and clear top coats are sprayed.

[Chadheckler1]

Still a problem...

Well...after shielding the entire guitar I still have the "Static" problem. I ended up using tape and have no more than 1 ohm from the furthest points away from each other.

While I was in there I cut a space in the copper shielding around the P-90's so that they were "open" and there is a definately a noticeable difference in tone...for the better IMO. Thanks Dave!

Any further ideas on the static issue or should I just wait until summer time when it is 80% RH and see if if goes away.

The only other thing I was thinking is that I built up a ton of static "Memory" on the lacquer surface when buffing the guitar at 20% RH and I might be able to wipe it down with some kind of solution to bring it back to a neutral surface...does that even make sense or am I just screwed?

[Joe Gwinn]

Well...after shielding the entire guitar I still have the "Static" problem. I ended up using tape and have no more than 1 ohm from the furthest points away from each other.

Most likely, some metallic component is still not grounded. Poke around with an ohmmeter probe until you find it.

As long as the resistance to ground (use the cable jack shield terminal) does not exceed 10,000 ohms, the item is considered grounded for this purpose. In very dry areas, an intermediate value of resistance to ground can reduce sparks even as it drains the static charge away.

While I was in there I cut a space in the copper shielding around the P-90's so that they were "open" and there is a definitely a noticeable difference in tone...for the better IMO. Thanks Dave!

You killed the eddy currents!

Any further ideas on the static issue or should I just wait until summer time when it is 80% RH and see if if goes away.

The only other thing I was thinking is that I built up a ton of static "Memory" on the lacquer surface when buffing the guitar at 20% RH and I might be able to wipe it down with some kind of solution to bring it back to a neutral surface...does that even make sense or am I just screwed?

Sweat will work just fine, so play harder?

Seriously, the static from buffing is long gone, and the sparks are coming from static generated in the last few minutes.

As mentioned above, I think something isn't properly grounded, and the quickest way to find out what is to probe around with an ohmmeter.


Another possibility is that the circuit diagram of the grounding system of the guitar isn't right, such that what should be a harmless spark causes the spark pulse current to flow through some part of the music circuit. The classic solution is a star ground system, where all grounds (including the cable shield) come to a single place by independent paths.


Another thing that can cause a problem even with a well shielded guitar is if the shield of the guitar-amp cable is deficient and/or the amp doesn't handle spark pulse currents on the cable shield properly. This is easily tested by popping sparks to various parts of the system, starting with the amp with a shorting plug installed in the input. then replacing the shorting plug with a long cable shorted at the guitar end, and so on.

[roundmidnight]

I have experienced similar problems on at least 3 different guitars. Mine have usually involved static charge building up on the pick guard and creating a crackling sound via transfer to the pickups. Not sure if you have a pick guard on this guitar. The pickup shielding & wire insulation may play a role in these problems.

On one guitar I used copper foil to create a sink for static charge on the back of the pickguard and soldered a lead that connected to the cavity ground. On that particular guitar, problem solved! A year later, encountered the same problem on a different guitar and after several weeks of dicking around finally removed the pickguard and, problem solved. The crazy thing is that I have not found one bombproof way of dealing with static crackling issues. Also have spent hours verifying/improving cavity shielding and grounding on these problem guitars without a 100% solution. Years ago purchased about 20 lb of high quality copper foil sheets and whenever I run into problems with noise usually try shielding cavities, attaching foil to pickguards, etc. Most of the time this helps but with some materials (plastics/finishes?) nothing I have tried seems to completely eliminate the problem.

I find that some shirts/sweaters (fabrics) cause more static than others.

Good luck.

RM